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265 Cards in this Set
- Front
- Back
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What are the forms in which a virus can be structurally?
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- Naked virus with icosahedral capsid
- Enveloped virus with icosahedral capsid - Enveloped virus with helical capsid |
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What are the components of a naked virus?
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- Icosahedral capsid
- Nucleic acid |
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What are the components of an enveloped virus?
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- Lipid bilayer + surface protein = envelope
- Icosahedral capsid or helical capsid - Nucleic acid inside capsid |
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What is the term for the exchange of genes between two chromosomes by crossing over within regions of significant base sequence homology?
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Recombination
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What is the term for when viruses with segmented genomes (eg, influenza viruses) exchange segments (cause of worldwide influenza pandemics)?
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Reassortment
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What is the term for when 1 of 2 viruses that infect the cell has a mutation that results in a non-functional protein (the non-mutate virus "complements" the mutated one by making a functional protein that serves both viruses)?
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Complementation
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What is the term for when a cell is infected simultaneously by two viruses and the genome of virus A can be partially or completely coated with surface proteins of virus B?
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Phenotypic mixing
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What is Recombination?
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Exchange of genes between 2 chromosomes by crossing over within regions of significant base sequence homology
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What is Reassortment?
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- When viruses with segmented genomes (eg, influenza virus) exchange segments
- High-frequency recombination - Cause of world-wide influenza pandemics |
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What causes world-wide influenza pandemics?
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Viral reassortment
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What is Complementation?
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- When 1 of 2 viruses that infect the cell has a mutation that results in a non-functional protein
- The non-mutated virus "complements" the mutated one by making a functional protein that serves both viruses |
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What is Phenotypic Mixing?
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- Occurs with simultaneous infection of a cell with 2 viruses
- Genome of virus A can be partially or completely coated (forming pseudovirion) with the surface proteins of virus B - Type B protein coat determines the tropism (infectivity) of the hybrid virus - However, the progeny from this infection have a type A coat that is encoded by its type A genetic material |
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What are the types of viral vaccines?
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- Live attenuated vaccines
- Killed - Recombinant |
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What is the effect of live attenuated virus vaccines?
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- Induce humoral and cell-mediated immunity
- Some have reverted to virulence on rare occasions - No boosters needed |
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What is the effect of killed virus vaccines?
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- Only induce humoral immunity
- Stable, no chance to revert to virulence |
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What are the types of live attenuated virus vaccines?
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"Live! One night only! See SMALL YELLOW CHICKENs get vaccinated with SABIN and MMR! It's INcredible!"
- Smallpox - Yellow fever - Chickenpox (Varicella Zoster) - Sabin Polio Virus - MMR: Measles, Mumps, Rubella - Influenza (intranasal) |
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What are the types of killed viral vaccines?
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SalK = Killed
RIP Always - Rabies - Influenza (injected) - Polio (SalK) - HAV |
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What are the types of recombinant viral vaccines?
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- HBV (antigen = recombinant HBsAg)
- HPV (types 6, 11, 16, and 18) |
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Which type of vaccine is dangerous for immunocompromised patients or their close contacts?
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Live Attenuated Vaccines
"Live! One night only! See SMALL YELLOW CHICKENs get vaccinated with SABIN and MMR! It's INcredible!" - Smallpox - Yellow fever - Chickenpox (Varicella Zoster) - Sabin Polio Virus - MMR: Measles, Mumps, Rubella - Influenza (intranasal) |
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Which live attenuated vaccine can be given to HIV-positive patients who do not show signs of immunodeficiency yet?
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MMR = Measles, Mumps, Rubella
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What are the two types of Polio vaccines? Difference?
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- Sabin = live attenuated vaccine
- SalK = Killed vaccine |
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What are the two types of influenza vaccines? Difference?
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- Influenza intranasal = live attenuated vaccine
- Influenza injected = killed vaccine |
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Which types of HPV are in the recombinant vaccine?
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Types 6, 11, 16, and 18
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What are the common characteristics of DNA viral genomes?
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- All DNA viruses are dsDNA (except Parvoviridae = "part-of-a-virus" is ssDNA)
- All are linear (except Papilloma-, Polyoma-, and Hepadnaviruses which are circular) |
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Which DNA virus is the exception to all DNA viruses being dsDNA?
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Parvovirus = "part-of-a-virus" is ssDNA
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Which DNA viruses are the exception to all DNA viruses being linear?
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Circular:
- Papillomavirus - Polyomavirus - Hepadnaviruses |
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What are the common characteristics of RNA viral genomes?
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- All RNA viruses are ssRNA (except Reoviridae = "repeato-virus" is dsRNA)
- Either positive stranded ssRNA or negative stranded ssRNA |
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Which RNA viruses have positive-stranded RNA?
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I went to a RETRO TOGA party, where I drank FLAVored CORONA and ate HIPPY CALIfornia PICkles
- Retrovirus - Togavirus - Flavivirus - Coronavirus - Hepevirus - Calicivirus - Picornavirus |
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What does this mnemonic help you remember: "I went to a RETRO TOGA party, where I drank FLAVored CORONA and ate HIPPY CALIfornia PICkles"?
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These are the positive-stranded ssRNA viruses
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Purified nucleic acids from what viruses are infectious?
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- Most dsDNA viruses (except poxviruses and HBV)
- (+) strand ssRNA (~mRNA) viruses |
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Purified nucleic acids from what viruses are not infectious? Why?
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- Poxvirus and HBV (dsDNA)
- (-) strand ssRNA viruses - dsRNA viruses * These viruses require polymerases contained in the complete virion |
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Where does viral replication occur?
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DNA viruses
- All replicate in the nucleus (except poxvirus) RNA viruses - All replicate in the cytoplasm (except influenza virus and retroviruses) |
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Which viruses replicate in the nucleus?
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DNA viruses (except poxvirus)
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Which viruses replicate in the cytoplasm?
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RNA viruses (except influenza and retroviruses)
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Which viruses are naked (non-enveloped)?
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"Give PAPP smears and CPR to a NAKED HIPPY"
*DNA = PAPP - Papillomavirus - Adenovirus - Parvovirus - Polyomavirus *RNA = CPR and HIPPY - Calicivirus - Picornavirus - Reovirus - Hepevirus |
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How do enveloped viruses acquire their envelopes?
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- From plasma membrane when they exit from the cell
- Exceptions: herpesviruses - acquire envelopes from nuclear membrane |
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What are the DNA viruses?
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HHAPPPPy viruses:
- Hepadna - Herpes - Adeno - Pox - Parvo - Papilloma - Polyoma |
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What are the general characteristics about DNA viruses?
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- Double stranded (except parvo - "part-of-a-virus" is ssNA)
- Linear (except papilloma and polyoma (circular, supercoiled) and hepadna (circular, incomplete)) - Icosahedral (except pox - complex) - Replicate in the nucleus (except pox - carries own DNA-dependent RNA polymerase) |
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Which of the DNA viruses are enveloped?
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Enveloped have *
*Herpesvirus *Hepadnavirus -Adenovirus -Parvovirus -Papillomavirus -Polyomavirus *Poxvirus |
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Which of the DNA viruses are not enveloped?
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Non-enveloped have *
-Herpesvirus -Hepadnavirus *Adenovirus *Parvovirus *Papillomavirus *Polyomavirus -Poxvirus |
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Which DNA viruses are DS and linear?
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DS and linear = *
*Herpes -Hepadna *Adeno -Parvovirus -Papillomavirus -Polyomavirus *Poxvirus |
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Which DNA viruses are DS and circular?
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DS and circular = *
-Herpesvirus *Hepadnavirus (partially DS) -Adenovirus -Parvovirus *Papillomavirus *Polyomavirus -Poxvirus |
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Which DNA viruses are SS and linear (-)?
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SS and linear (-) = *
-Herpesvirus -Hepadnavirus -Adenovirus *Parvovirus -Papillomavirus -Polyomavirus -Poxvirus |
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Which viruses are enveloped and contain DS/linear DNA?
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*Herpesvirus
-Hepadnavirus -Adenovirus -Parvovirus -Papillomavirus -Polyomavirus *Poxvirus |
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Which viruses are enveloped and contain DS/circular DNA?
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-Herpesvirus
*Hepadnavirus -Adenovirus -Parvovirus -Papillomavirus -Polyomavirus -Poxvirus |
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Which viruses are not enveloped and contain DS/linear DNA?
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-Herpesvirus
-Hepadnavirus *Adenovirus -Parvovirus -Papillomavirus -Polyomavirus -Poxvirus |
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Which viruses are not enveloped and contain SS/linear (-) DNA?
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-Herpesvirus
-Hepadnavirus -Adenovirus *Parvovirus -Papillomavirus -Polyomavirus -Poxvirus |
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Which viruses are not enveloped and contain DS/circular DNA?
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-Herpesvirus
-Hepadnavirus -Adenovirus -Parvovirus *Papillomavirus *Polyomavirus -Poxvirus |
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What are the types of Herpesviruses?
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- HSV-1
- HSV-2 - VZV (HHV-3) - EBV (HHV-4) - CMV (HHV-5) - HHV-6 - HHV-7 - HHV-8 |
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Which virus causes oral (and some genital) lesions, spontaneous temporal lobe encephalitis, and keratoconjunctivitis? Characteristics?
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HSV-1 (Herpesvirus - enveloped, DS and linear DNA)
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Which virus causes genital (and some oral) lesions?
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HSV-2 (Herpesvirus - enveloped, DS and linear DNA)
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Which virus causes chickenpox and zoster (shingles)?
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Varicella Zoster Virus / HHV-3 (Herpesvirus - enveloped, DS and linear DNA)
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Which virus causes mononucleosis, Burkitt lymphoma, and Hodgkin lymphoma?
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Ebstein-Barr Virus (EBV) / HHV-4 (Herpesvirus - enveloped, DS and linear DNA)
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Which virus causes infection in immunosuppressed patients (AIDS retinitis), especially transplant recipients and can also cause congenital defects?
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Cytomegalovirus (CMV) / HHV-5 (Herpesvirus - enveloped, DS and linear DNA)
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Which virus causes roseola (exanthem subitum)?
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HHV-6 and less commonly HHV-7 (Herpesvirus - enveloped, DS and linear DNA)
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Which virus causes Kaposi sarcoma?
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HHV-8 (Herpesvirus - enveloped, DS and linear DNA)
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For which Herpesvirus is there a vaccine available? Type?
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VZV / HHV-3 - live attenuated vaccine
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Which DNA virus causes acute or chronic hepatitis? Is there a vaccine for it?
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HBV (Hepadnavirus - enveloped, partially DS and circular DNA)
- Killed vaccine available that contains HBV surface antigen - Also virus has reverse transcriptase even though it is not a retrovirus |
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Which virus can cause febrile pharyngitis (sore throat), acute hemorrhagic cystiits, pneumonia, and conjunctivitis (pink eye)?
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Adenovirus (no envelope, DS and linear DNA)
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Which virus causes aplastic crises in sickle cell disease, "slapped cheeks" rash in children, hydrops fetalis in fetus, and RBC aplasia and rheumatoid arthritis like symptoms in adults?
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Parvovirus B19 (no envelope, SS and linear (-) DNA)
- Smallest DNA virus |
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Which virus causes warts?
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HPV - strains 1, 2, 6, and 11
(papillomavirus - no envelope, DS and circular DNA) |
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Which virus causes CIN (cervical intraepithelial neoplasia) and cervical cancer?
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HPV - strains 16 and 18
(papillomavirus - no envelope, DS and circular DNA) |
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Which virus causes progressive multifocal leukoencephalopathy (PML) in HIV patients?
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JC virus (type of Polyomavirus - no envelope, DS and circular DNA)
(JC = Junky Cerebrum) |
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Which virus commonly targets the kidneys in transplant patients?
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BK virus (type of Polyomavirus - no envelope, DS and circular DNA)
(BK = Bad Kidney) |
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Which virus, although eradicated, could be used in germ warfare?
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Smallpox (poxvirus - enveloped and DS, linear - largest DNA virus)
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Which virus is associated with "milkmaid blisters"?
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Cowpox (poxvirus - enveloped and DS, linear - largest DNA virus)
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Which virus is associated with flesh-colored dome lesions with a central umbilicated dimple?
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Molluscum contagiosum (poxvirus - enveloped and DS, linear - largest DNA virus)
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What is the medical importance of Hepadnavirus?
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HBV:
- Acute or chronic hepatitis - Vaccine available - contains HBV surface antigen (killed vaccine) - Not a retrovirus bu has reverse transcriptase |
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What is the medical importance of Adenovirus?
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- Febrile pharyngitis - sore throat
- Acute hemorrhagic cystitis - Pneumonia - Conjunctivitis - pink eye |
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What is the medical importance of Parvovirus?
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B19 virus
- Aplastic crises in sickle cell disease - "Slapped cheeks" rash in children: erythema infectiosum (fifth disease) - RBC destruction in fetus leads to hydrops fetalis and death - Pure RBC aplasia and rheumatoid arthritis-like symptoms in adults |
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What is the medical importance of Papillomaviruses?
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HPV
- Warts (1, 2, 6, or 11) - CIN and Cervical Cancer (16, 18) - Recombinant vaccine available for strains 6, 11, 16, and 18 |
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What is the medical importance of Polyomaviruses?
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JC Virus:
- Progressive multifocal leukoencephalopathy (PML) in HIV - JC = Junky Cerebrum BK Virus: - Transplant patients, commonly targets kidney - BK = Bad Kidney |
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What is the medical importance of Poxviruses?
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Smallpox
- Eradicated, but could be used in germ warfare Cowpox - Milkmaid blisters Molluscum contagiosum - Flesh-colored dome lesions with central umbilicated dimple |
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What diseases/symptoms can HSV-1 cause?
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- Gingivostomatitis: inflammation of mouth and lips
- Keratoconjunctivitis: inflammation of cornea and conjunctiva - Temporal lobe encephalitis (most common cause of sporadic encephalitis in US) - Herpes labialis: cold sore on lip - Latent in trigeminal ganglia |
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How is HSV-1 spread?
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Spread via respiratory secretions and saliva
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What diseases/symptoms can HSV-2 cause?
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- Herpes genitalis: cold sores on genitals
- Latent in sacral ganglia |
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How is HSV-2 spread?
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Sexual contact or perinatally
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What diseases/symptoms can HHV-3 cause?
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Varicella Zoster virus
- Chickenpox - Shingles (most common complication is post-herpetic neuralgia) - Encephalitis - Pneumonia - Latent in dorsal root or trigeminal ganglia |
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How is VZV / HHV-3 transmitted?
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Respiratory secretions
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What diseases/symptoms can HHV-4 cause?
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Ebstein-Barr Virus
- Mononucleosis: fever, hepatosplenomegaly, pharyngitis, lymphadenopathy (especially posterior cervical nodes) - Associated with Hodgkin Lymphoma, endemic Burkitt Lymphoma, and Nasopharyngeal Carcinoma |
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How is EBV / HHV-4 transmitted?
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Respiratory secretions and saliva
- AKA "Kissing disease" because commonly seen in teens, young adults |
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What cells are affected by EBV / HHV-4?
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- B cells are infected
- Atypical lymphocytes seen on peripheral blood smear are not infected B cells but rather reactive cytotoxic T cells |
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How do you detect infection of EBV / HHV-4 (eg, mononucleosis)?
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Monospot test: heterophile antibodies detected by agglutination of sheep or horse RBCs
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What diseases/symptoms can HHV-5 cause?
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Cytomegalovirus
- Congenital infection, mononucleosis (- monospot test) - Pneumonia - Retinitis - Latent in mononuclear cells |
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How do you diagnose HHV-5 / CMV infection?
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Infected cells have characteristics "owl eye" inclusions
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How is HHV-5 / CMV transmitted?
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- Congenitally
- Transfusion - Sexual contact - Saliva - Urine - Transplant |
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What diseases/symptoms can HHV-6 cause?
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Roseola
- High fevers for several days - Can cause seizures - Diffuse macular rash (picture) |
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How is HHV-6 (Roseola) transmitted?
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Saliva
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What diseases/symptoms can HHV-8 cause?
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Kaposi Sarcoma
- Neoplasm of endothelial cells - Seen in HIV/AIDS and transplant patients - Dark / violaceous flat and nodular skin lesions (picture) representing endothelial growths - Can also affect GI tract and lungs |
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How is HHV-8 (Kaposi Sarcoma) transmited?
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Sexual contact
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Which Herpesviruses are latent in certain cells? Which cells?
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- HSV-1: latent in trigeminal ganglia
- HSV-2: latent in sacral ganglia - VZV / HHV-3: latent in dorsal root or trigeminal ganglia - CMV / HHV-5: latent in mononuclear cells |
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What does this image show? Sign of?
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Keratoconjunctivitis (inflammation of cornea and conjunctiva)
- Sign of HSV-1 infection |
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What does this image show? Sign of?
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Herpes Labialis
- Sign of HSV-1 infection |
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What does this image show? Sign of?
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Herpes genitalis
- Sign of HSV-2 infection |
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What does this image show? Sign of?
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Shingles (VZV was latent in dorsal root)
- Sign of VZV / HHV-3 infection |
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What does this image show? Sign of?
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Atypical lymphocytes are reactive cytotoxic T cells
- Sign of EBV / mononucleosis - Confirm with Monospot test (heterophile antibodies detected by agglutination of sheep or horse RBCs) |
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What does this image show? Sign of?
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"Owl eye" inclusions
- Infected mononuclear cells with CMV / HHV-5 - Can cause mononucleosis but would have negative monospot test |
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What does this image show? Sign of?
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Diffuse macular rash = Roseola
- Sign of HHV-6 infection |
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What does this image show? Sign of?
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Dark / violaceous flat and nodular skin lesions representing endothelial growths
- Sign of HHV-8 infection (Kaposi Sarcoma) |
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How do you diagnose infection with HSV?
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- Viral culture for skin / genitalia
- CSF PCR for herpes encephalitis - Tzanck test (genital herpes) - a smear of an opened skin vesicle to detect multinucleated giant cells (picture) - Infected cells also have intranuclear Cowdry A inclusions |
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What does this image show? Sign of?
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Positive Tzanck smear in genital herpes (HSV-2)
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What are the types of RNA viruses?
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- Reovirus
- Picornavirus - Hepevirus - Calicivirus - Flavivirus - Togavirus - Retrovirus - Coronavirus - Orthomyxovirus - Paramyxovirus - Rhabdovirus - Filovirus - Arenavirus - Bunyavirus - Delta virus |
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Which RNA viruses are enveloped?
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*Enveloped
- Reovirus - Picornavirus - Hepevirus - Calicivirus * Flavivirus * Togavirus * Retrovirus * Coronavirus * Orthomyxovirus * Paramyxovirus * Rhabdovirus * Filovirus * Arenavirus * Bunyavirus * Delta virus |
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Which RNA viruses are not enveloped?
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* Not enveloped
* Reovirus * Picornavirus * Hepevirus * Calicivirus - Flavivirus - Togavirus - Retrovirus - Coronavirus - Orthomyxovirus - Paramyxovirus - Rhabdovirus - Filovirus - Arenavirus - Bunyavirus - Delta virus |
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Which RNA viruses are DS?
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DS = *
* Reovirus - linear (10-12 segments) - Picornavirus - Hepevirus - Calicivirus - Flavivirus - Togavirus - Retrovirus - Coronavirus - Orthomyxovirus - Paramyxovirus - Rhabdovirus - Filovirus - Arenavirus - Bunyavirus - Delta virus |
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Which viruses are (+) linear ssRNA?
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+ssRNA = *
- Reovirus * Picornavirus * Hepevirus * Calicivirus * Flavivirus * Togavirus * Retrovirus * Coronavirus - Orthomyxovirus - Paramyxovirus - Rhabdovirus - Filovirus - Arenavirus - Bunyavirus - Delta virus |
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Which viruses are (-) linear ssRNA?
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(-) ssRNA, linear = *
- Reovirus - Picornavirus - Hepevirus - Calicivirus - Flavivirus - Togavirus - Retrovirus - Coronavirus * Orthomyxovirus * Paramyxovirus * Rhabdovirus * Filovirus - Arenavirus - Bunyavirus - Delta virus |
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Which viruses are (-) circular ssRNA?
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(-) ssRNA, circular
- Reovirus - Picornavirus - Hepevirus - Calicivirus - Flavivirus - Togavirus - Retrovirus - Coronavirus - Orthomyxovirus - Paramyxovirus - Rhabdovirus - Filovirus * Arenavirus * Bunyavirus * Delta virus |
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Which RNA viruses are icosahedral?
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* Reovirus
* Picornavirus * Hepevirus * Calicivirus * Flavivirus * Togavirus * Retrovirus - Coronavirus - Orthomyxovirus - Paramyxovirus - Rhabdovirus - Filovirus - Arenavirus - Bunyavirus - Delta virus |
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Which RNA viruses are helical?
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- Reovirus
- Picornavirus - Hepevirus - Calicivirus - Flavivirus - Togavirus - Retrovirus * Coronavirus * Orthomyxovirus * Paramyxovirus * Rhabdovirus * Filovirus * Arenavirus * Bunyavirus * Delta virus |
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What are the types of Reoviruses?
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- Coltivirus
- Rotavirus |
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What is the #1 cause of fatal diarrhea in children?
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Rotavirus (Reovirus - no envelope, DS linear, icosahedral (double))
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What is the medical importance of the Coltivirus?
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- Causes Colorado Tick Fever
- Type of arbovirus - transmitted by arthropods (ticks) - Reovirus - no envelope, DS linear (10-12 segments), icosahedral (double) |
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What is the medical importance of the Rotavirus?
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- #1 cause of fatal diarrhea in children
- Reovirus - no envelope, DS linear (10-12 segments), icosahedral (double) |
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What are the types of Picornaviruses?
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PERCH:
- Poliovirus - Echovirus - Rhinovirus - Coxsackievirus - HAV |
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What is the medical importance of the Poliovirus?
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Causes Polio
- Salk (killed / injected) and Sabin (live attenuated / oral) vaccines - Picornavirus (no envelope, SS (+) linear, icosahedral) |
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What is the medical importance of the Echovirus?
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Causes aseptic meningitis
- Picornavirus (no envelope, SS (+) linear, icosahedral) |
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What is the medical importance of Rhinovirus?
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"Common cold"
- Picornavirus (no envelope, SS (+) linear, icosahedral) |
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What is the medical importance of the Coxsackievirus?
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- Aseptic meningitis
- Herpangina (mouth blisters, fever) - Hand, foot, and mouth disease - Myocarditis and pericarditis - Picornavirus (no envelope, SS (+) linear, icosahedral) |
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What is the medical importance of the HAV?
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Causes Acute Viral Hepatitis
- Picornavirus (no envelope, SS (+) linear, icosahedral) |
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What is the medical importance of the Hepevirus family?
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- Hepatitis E Virus (HEV)
- No envelope, SS (+) linear, icosahedral |
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What is the medical importance of the Calicivirus family?
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Norovirus - viral gastroenteritis
- No envelope, SS (+) linear, icosahedral |
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What are the types of Flaviviruses?
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- HCV
- Yellow Fever - Dengue Fever - St. Louis Encephalitis - West Nile Virus |
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What are the characteristics of Flaviviruses?
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- Envelope
- SS (+) linear - Icosahedral |
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What is the medical importance of Togaviruses? Characteristics?
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- Rubella
- Eastern equine encephalitis - Western equine encephalitis - Envelope, SS(+) linear, Icosahedral |
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What is the medical importance of Retroviruses? Types? Characteristics?
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- Have reverse transcriptase
- HIV: AIDS (complex and conical) - HTLV: T-Cell Leukemia (icosahedral) - Enveloped, SS (+) Linear |
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What is the medical importance of Coronaviruses? Characteristics?
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- Common cold
- SARS - Envelope, SS (+) linear, Helical |
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What is the medical importance of Orthomyxoviruses? Characteristics?
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Influenza Virus
- Envelope - SS (-) Linear (8 segments) - Helical |
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What is the medical importance of Paramyxoviruses? Characteristics?
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PaRaMyxovirus:
- Parainfluenza = Croup - RSV = bronchiolitis in babies, rx = ribavirin - Measles - Mumps - Envelope, SS (-) linear (non-segmented), helical |
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What does RSV cause? Treatment? Characteristics?
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- Causes bronchiolitis in babies
- Treat with Ribavirin - Paramyxovirus: enveloped, SS (-) linear (non-segmented), helical |
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What is the medical importance of Rhabdoviruses? Characteristics?
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Rabies
- Envelope - SS (-) linear - Helical |
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What is the medical importance of Filoviruses? Characteristics?
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Ebola / Marburg hemorrhagic fever (often fatal)
- Envelope - SS (-) linear - Helical |
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What is the medical importance of Arenaviruses? Characteristics?
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- LCMV: Lymphocytic Choriomeningitis Virus
- Lassa Fever Encephalitis (spread by mice) - Enveloped, SS (-) Circular (2 segments), Helical |
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What is the medical importance of Bunyaviruses? Characteristics?
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- California encephalitis
- Sandfly / Rift Valley fevers - Crimean-Congo hemorrhagic fever - Hantavirus - hemorrhagic fever, pneumonia - Enveloped, SS (-) circular (3 segments), helical |
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What is the medical importance of Delta Virus? Characteristics?
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- HDV: defective virus that requires HBV co-infection
- Enveloped, SS (-) circular, uncertain capsid symmetry |
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What are the negative stranded viruses? What do they require?
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Always Bring Polymerase Or Fail Replication
- Arenaviruses - Bunyaviruses - Paramyxoviruses - Orthomyxoviruses - Filoviruses - Rhabdoviruses Must transcribe (-) strand to (+) - Virion brings its own RNA-dependent RNA polymerase |
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What are the segmented viruses? How many segments?
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All are RNA viruses: BOAR
- Bunyaviruses: 3 segments - Orthomyxoviruses (influenza): 8 segments - Arenaviruses: 2 segments - Reoviruses: 10-12 segments |
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What are the Picornaviruses?
|
PERCH on a "Peak" (PICO)
- Poliovirus - Echovirus - Rhinovirus - Coxsackievirus - HAV |
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What is unique about Picornaviruses?
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- Small RNA virus
- RNA is translated into 1 large polypeptide that is cleaved by proteases into functional viral proteins - Can cause aseptic (viral) meningitis (except Rhinovirus and HAV) - All are enteroviruses (fecal-oral spread) except rhinovirus |
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What are the characteristics of Rhinovirus? What does it cause?
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Picornavirus - non-enveloped RNA virus
- Cause of common cold - > 100 serologic types - Acid labile (destroyed by stomach acid) therefore does not infect the GI tract (unlike other picornaviruses) |
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What family of virus is Yellow Fever Virus? How is it transmitted? Symptoms?
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Flavivirus (also an arbovirus - transmitted by Aedes mosquitos)
- Virus has a monkey or human reservoir - Symptoms: high fever, black vomitus, and jaundice |
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Which virus causes high fever, black vomitus, and jaundice?
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Yellow Fever Virus (type of flavivirus)
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What is the most important global cause of infantile gastroenteritis? Characteristics?
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Rotavirus = Right Out The Anus
- Type of Reovirus - Segmented dsRNA virus - Major cause of acute diarrhea in US during winter, especially at day-care centers, kindergartens |
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What is the mechanism of action of Rotavirus? Implications?
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- Villous destruction with atrophy leads to decreased absorption of Na+ and loss of K+
- Major cause of acute diarrhea in Us during winter, especially in day-care centers and kindergartens - CDC recommends routine vaccination of all infants |
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What type of virus is Influenza Virus? Characteristics?
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Orthomyxovirus
- Enveloped - (-) ssRNA w/ 8-segment genome - Rapid genetic gchanges |
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What antigens are on influenza viruses? Actions?
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- Hemagglutinin - promotes viral entry
- Neuraminidase - promotes progeny virion release |
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Which protein on influenza virus promotes viral entry?
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Hemagglutinin
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Which protein on influenza virus promotes progeny virion release?
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Neuraminidase
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Patients infected with the influenza virus are at risk for what?
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Fatal bacterial superinfection
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What are the types and characteristics of the influenza vaccines?
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- Reformulated vaccine ("the flu shot" contains the viral strains most likely to appear during the flu season
- Killed viral vaccine (injected) most commonly used - Live attenuated (temperature sensitive) vaccine that replicates in the nose but not in the lung is administered intranasally |
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What are the types of genetic changes to the influenza vaccine? Which is more serious?
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- Genetic shift / antigenic shift
- Genetic drift Sudden Shift is more deadly than graDual Drift |
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What does genetic SHIFT of influenza viruses cause?
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Pandemics
- Reassortment of viral genome - Segments undergo high-frequency recombination, such as when human flu A virus combines with swine flu A virus |
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What does genetic DRIFT of influenza viruses cause?
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Epidemics
- Minor (antigenic drift) changes are based on random mutation |
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What kind of virus is Rubella? What disease does it cause?
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Togavirus
- Causes rubella, aka German (3-day) Measles - Fever, postauricular and other lymphadenopathy, arthralgias and fine rash - Mild disease in children, but severe congenitally |
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What are the impacts of Rubella (togavirus) if acquired congenitally?
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Serious congenital disease (a ToRCHeS infection):
- Blueberry muffin appearance indicates extramedullary hematopoiesis |
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What are the types of Paramyxoviruses?
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- Parainfluenzae
- Mumps - Measles - RSV |
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Which virus causes croup - seal-like barking cough?
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Parainfluenza (type of paramyxovirus)
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Which virus causes respiratory tract infections (bronchiolitis, pnuemonia) in infants?
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RSV (type of paramyxovirus)
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What are the characteristics of all paramyxoviruses?
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- Contain surface F (fusion) proteins
- F protein causes respiratory epithelial cells to fuse and form multinucleated cells |
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Which drug can prevent pneumonia caused by RSV infection in premature infants? Mechanism?
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Palivizumab - monoclonal antibody against F protein
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Which virus causes Koplik spots (left) and a descending maculopapular rash (right)
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Measles virus (a paramyxovirus)
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What are the characteristic symptoms of Measles infection?
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- Koplik spots - bright red spots with blue-white center on buccal mucosa that precedes measles rash by 1-2 days (left)
- Descending maculopapular, erythematous rash that includes limbs (right) 3 "C's" of measles: - Cough - Coryza (inflammation of nose) - Conjunctivitis |
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What are the possible sequelae of Measles infection?
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- SSPE: Subacute Sclerosing Panencephalitis (occurs years later)
- Encephalitis (1:2000) - Giant cell pneumonia (rarely, in immunosuppressed) |
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What can be used to prevent severe exfoliative dermatitis in malnourished children with Measles?
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Vitamin A
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Which virus causes Parotitis (picture), Orchitis (inflammation of testes), and aseptic Meningitis?
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Mumps virus (a type of paramyxovirus)
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What are the symptoms of Mumps?
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Mumps makes your parotid glands and testes as big as POM-poms
- Parotitis (picture) - Orchitis (inflammation of testes) - Aseptic Meningitis - Can cause sterility (especially after puberty) |
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Which virus is bullet-shaped?
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Rabies virus
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What cells are affected by the Rabies virus?
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Rabies virus characteristically infects Purkinje cells of the cerebellum and neurons in the hippocampus
- Cytoplasmic inclusions = Negri body (arrows) |
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What are the symptoms of Rabies Virus?
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- Long incubation period (weeks to months) before onset of symptoms
- Progression of disease: fever, malaise → agitation, photophobia, hydrophobia → paralysis, coma → death |
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From which animals is it more common to acquire Rabies virus?
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Bat, raccoon, and skunk bites more common than dog bites in US
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What is the pathophysiology of Rabies virus?
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Virus travels to the CNS (Purkinje cells of cerebellum and hippocampal neurons) by migrating in a retrograde fashion up nerve axons
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How should you treat a patient you think may be exposed to Rabies virus?
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- Wound cleansing
- Vaccination +/- rabies immune globulin |
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What are the types of Hepatitis viruses? Virus family? DNA/RNA?
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- HAV: RNA picornavirus
- HBV: DNA hepadnavirus - HCV: RNA flavivirus - HDV: RNA delta virus - HEV: RNA hepevirus |
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How are the Hepatitis viruses transmitted?
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- HAV: fecal-oral
- HBV: parenteral, sexual, maternal-fetal - HCV: primarily blood (IVDU, post-transfusion) - HDV: parenteral, sexual, maternal-fetal - HEV: fecal-oral, especially with waterborne epidemics * HAV and HEV: the vowels hit your bowels |
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What are the signs and symptoms of ALL hepatitis viruses?
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- Episodes of fever
- Jaundice - ↑ ALT and AST |
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Which Hepatitis viruses require a carrier?
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HBV, HCV, HDV
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What is the relative incubation time for the Hepatitis viruses?
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- HAV: short (weeks)
- HBV: long (months) - HCV: long - HDV: superinfection (HDV after HBV) is short - HDV: co-infection (HDV with HBV) is long - HEV: short |
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Which Hepatitis viruses have risk for progressing to hepatocellular carcinoma? How?
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- HBV (integrates into host genome, acts as oncogene
- HCV (from chronic inflammation) - HDV |
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What are the characteristics of HAV?
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- RNA picornavirus
- Fecal-oral transmission - No carrier - Short incubation time (weeks) - No risk for HCC - Usually "A"symptomatic, "A"cute, "A"lone (no carrier) |
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What are the characteristics of HBV?
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- DNA hepadnavirus
- Parenteral, sexual, or maternal-fetal transmission - Carrier - Long incubation time (months) - Risk for HCC (integrates into host genome and acts as oncogene) - DNA polymerase has both DNA- and RNA-dependent activities; upon entry into nucleus the polymerase functions to complete the partial dsDNA - The host RNA polymerase transcribes mRNA from viral DNA to make proteins - DNA polymerase then reverse transcribes viral RNA to DNA which helps form new viral particles |
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What are the characteristics of HCV?
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- RNA flavivirus
- Primarily transmitted via blood (IVDU, post-transfusion) - Carrier - Long incubation time - Risk of HCC (from chronic inflammation) - "C"hronic, "C"irrhosis, "C"arcinoma, "C"arrier |
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What are the characteristics of HDV?
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- RNA delta virus
- Parenteral, sexual, or maternal-fetal transmission - Carrier - Superinfection (HDV after HBV) has short incubation time - Co-infection (HDV with HBV) has long incubation time - Risk for HCC - "D"efective virus "d"ependent on HBV superinfection → ↓ prognosis |
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What are the characteristics of HEV?
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- RNA hepevirus
- Fecal-oral transmission, especially with waterborne epidemics - No carrier - Short incubation time - No risk for HCC - High mortality in pregnant women - "E"nteric, "E"xpectant mothers, "E"pidemic |
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What does it mean if your patient has anti-HAV (IgM)?
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Best test to detect active Hepatitis A infection
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What does it mean if your patient has anti-HAV (IgG)?
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Indicates prior HAV infection and/or prior vaccination; protects against re-infection
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What does it mean if your patient has HBsAg?
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Indicates hepatitis B infection (antigen found on surface of HBV)
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What does it mean if your patient has anti-HBs?
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Indicates immunity to Hepatitis B (antibody to HBsAg)
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What does it mean if your patient has anti-HBc (IgM)?
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Acute / recent infection with HCV (antibody to HBcAg)
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What does it mean if your patient has anti-HBc (IgG)?
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Prior exposure to HCV or chronic infection
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What does it mean if your patient has HBeAg?
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Active viral replication and therefore high transmissibility
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What does it mean if your patient has anti-HBe?
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Low transmissibility
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What is the best serologic marker to detect active Hepatitis A infection?
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Anti-HAV (IgM)
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What is the serologic marker that indicates prior HAV infection and/or prior vaccination?
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Anti-HAV (IgG)
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Which serologic marker protects against reinfection of HAV?
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Anti-HAV IgG
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Which serologic marker indicates hepatitis B infection?
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HBsAg
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Which serologic marker indicates immunity to Hepatitis B infection?
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Anti-HBs
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Which serologic marker is associated with the core of HBV?
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HBcAg
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Which serologic marker indicates acute / recent infection with HBV?
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Anti-HBc IgM
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Which serologic marker indicates prior exposure or chronic infection with HBV?
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Anti-HBc IgG
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Which serologic marker is positive during the window period of HBV infection?
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- Anti-HBc (IgG and IgM)
- Anti-HBe |
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Which serologic marker indicates active viral replication and high transmissibility of HBV?
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HBeAg
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Which serologic marker indicates low transmissibility of HBV?
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Anti-HBe
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When is the ratio of ALT > AST?
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Viral hepatitis
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When is the ratio of AST > ALT?
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Alcoholic hepatitis
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Which serologic markers are present during Acute HBV? What do these markers mean?
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- HBsAg: hepatitis B infection
- HBeAg: high transmissibility and active viral replication - Anti-HBc IgM: acute / recent HBV infection |
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Which serologic markers are present during the window period of HBV infection? What do these markers mean?
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- Anti-HBe: low transmissibility
- Anti-HBc IgM: acute / recent HBV infection |
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Which serologic markers are present during Chronic HBV (high infectivity)? What do these markers mean?
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- HBsAg: hepatitis B infection
- HBeAg: high transmissibility and active viral replication - Anti-HBc IgG: prior exposure or chronic infection |
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Which serologic markers are present during Chronic HBV (low infectivity)? What do these markers mean?
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- HBsAg: hepatitis B infection
- Anti-HBe: low transmissibility - Anti-HBc IgG: prior exposure or chronic infection |
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Which serologic markers are present during Recovery from HBV? What do these markers mean?
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- Anti-HBs: immunity to HBV
- Anti-HBe: low transmissibility - Anti-HBc IgG: prior exposure or chronic infection |
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Which serologic markers are present if immunized to HBV? What do these markers mean?
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Anti-HBs: indicates immunity to HBV
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What kind of virus is HIV?
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Retrovirus
- Enveloped - SS (+) linear RNA - Diploid genome: 2 molecules of RNA - Complex and conical |
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What are the structural genes (proteins coded for) by HIV?
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- env (gp120 and gp41)
- gag (p24) - pol |
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What does the "env" gene by HIV code for?
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gp120 and gp41
- Formed from cleavage of gp160 to form envelope glycoproteins - gp120: attachment to host CD4+ T cell - gp41: fusion and entry |
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What does the "gag" gene by HIV code for?
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p24
- Capsid protein |
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What does the "pol" gene by HIV code for?
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- Reverse transcriptase
- Aspartate protease - Integrase |
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Which HIV gene/protein is responsible for attachment to host CD4+ T cell?
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gp120 glycoprotein
- Formed from cleavage of gp160 which is encoded by "env" gene - One of the "env"elope proteins |
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Which HIV gene/protein is responsible for fusion and entry?
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gp41 glycoprotein
- Formed from cleavage of gp160 which is encoded by "env" gene - One of the "env"elope proteins |
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Which HIV gene/protein is the capsid protein?
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p24 protein
- "gag" gene |
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Which HIV gene encodes reverse transcriptase, aspartate protease, and integrase?
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"pol" gene
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What is the function of Reverse Transcriptase in HIV?
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- Synthesizes dsDNA from RNA
- dsDNA then integrates into host genome |
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What does HIV bind on T cells?
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- CCR5 co-receptor (early) OR CXCR4 co-receptor (late)
- CD4 |
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What does HIV bind on macrophages?
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- CCR5 co-receptor
- CD4 |
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What can give someone immunity to HIV? How?
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Homozygous CCR5 mutation (usually the virus will bind this co-receptor on T cells and macrophages)
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What can give someone a slower course of HIV? How?
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Heterozygous CCR5 mutation (usually the virus will bind this co-receptor on T cells and macrophages)
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How do you make an initial diagnosis of HIV infection?
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ELISA - sensitive, so it rules out (SNOUT) but has a high false-positive rate and low threshold
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How do you make a confirmatory diagnosis of HIV infection?
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Western Blot assay confirms positive ELISA results
- Specific so rules in (SPIN) - High false-negative rate and high threshold |
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How can you determine the amount of HIV RNA in the plasma? Implications of this test?
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HIV PCR / viral load test
- High viral load associated with poor prognosis - Also can be used to monitor effects of drug therapy |
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How do you diagnose AIDS?
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≤ 200 CD4+ cells / mm3
(normal 500-1500 cells/mm3) OR HIV positive with AIDS defining condition (eg, Pneumocystis pneumonia) OR CD4 percentage < 14% |
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What is the use of ELISA and Western Blot tests for HIV?
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Looks for antibodies to viral proteins
- Both often falsely negative in the first 1-2 months of HIV infection - Both often falsely positive initially in babies born to infected mothers (anti-gp120 crosses placenta) - ELISA used first to rule out (sensitive) - Western blot used second to rule in (specific) |
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What are the four stages of untreated HIV infection?
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Four F's:
1. Flu-like (acute) 2. Feeling fine (latent) 3. Falling count 4. Final criss |
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What happens during the latent phase of HIV infection?
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Virus replicates in the lymph nodes
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What happens to the CD4+ T-cell count during an HIV infection?
|
Red line
- Primary infection: drops from normal to ~500 over ~1 month - Latency: increases initially within a couple of months but eventually drops over a number of years - Late in disease: count drops more significantly first to moderate immunocompromise (<400) and eventually into AIDS diagnosis (<200) |
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What happens to the HIV RNA copies / mL plasma during an HIV infection?
|
Blue line
- Primary infection: spikes within 2 months - Drops back down during clinical latency - Increases when latent period ends / immunocompromise |
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What pathogen(s) cause a systemic presentation in HIV-positive adults?
|
Histoplasma capsulatum
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What pathogen(s) cause a dermatologic presentation in HIV-positive adults?
|
- Candida albicans
- EBV - Bartonella henselae |
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What pathogen(s) cause a gastrointestinal presentation in HIV-positive adults?
|
Cryptosporidium species
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What pathogen(s) cause a neurologic presentation in HIV-positive adults?
|
- Toxoplasma gondii
- HIV itself - JC virus reactivation (cause of PML) - Cryptococcus neoformans - CMV |
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What pathogen(s) cause an oncologic presentation in HIV-positive adults?
|
- EBV
- HPV - HHV-8 |
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What pathogen(s) cause a respiratory presentation in HIV-positive adults?
|
- CMV
- Aspergillus fumigatus - Pneumocystis jirovecii - S. pneumoniae - Mycobacterium avium-intracellulare (aka Mycobacterium Avium Complex - MAC) |
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Which pathogen causes low-grade fevers, cough, hepatosplenomegaly, and tongue ulcers in HIV-positive adults? Lab findings? Other?
|
Histoplasma capsulatum
- Oval yeast cells within macrophages - CD4+ < 100 cells / mm3 - Usually H. capsulatum only causes pulmonary symptoms in immunocompetent hosts |
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Which pathogen causes fluffy white cottage-cheese lesions in HIV-positive adults? Lab findings? Other?
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Candida albicans
- Pseudohyphae - Commonly oral if CD4+ < 400 cells/mm3 - Esophageal if CD4+ < 100 cells/mm3 - C. albicans causes oral thrush and esophagitis |
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Which pathogen causes hairy leukoplakia in HIV-positive adults? Findings? Other?
|
Ebstein Barr Virus (EBV)
- Often on lateral tongue |
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Which pathogen causes superficial vascular proliferation in HIV-positive adults? Lab findings? Other?
|
Bartonella henselae
- Biopsy reveals neutrophilic inflammation - B. henselae causes bacillary angiomatosis |
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Which pathogen causes chronic, watery diarrhea in HIV-positive adults? Lab findings? Other?
|
Cryptosporidium species
- Acid-fast cysts seen in stool - Especially when CD4+ < 200 cells / mm3 |
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Which pathogen causes abscesses in HIV-positive adults? Lab findings? Other?
|
Toxoplasma gondii
- Many ring-enhancing lesions on imaging - CD4+ < 100 cells/mm3 |
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Which pathogen causes dementia in HIV-positive adults? Other?
|
Directly associated with HIV
- Must differentiate from other causes |
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Which pathogen causes encephalopathy in HIV-positive adults? Lab findings? Other?
|
JC virus reactivation
- Cause of PML (progressive multifocal leukoencephalopathy) - Due to reactivation of a latent virus - Results in demyelination - CD4+ < 200 cells/mm3 |
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Which pathogen causes meningitis in HIV-positive adults? Lab findings? Other?
|
Cryptococcus neoformans
- India ink stain reveals yeast with narrow-based budding and large capsules - CD4+ < 50 cells/mm3 |
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Which pathogen causes retinitis in HIV-positive adults? Lab findings? Other?
|
Cytomegalovirus (CMV)
- Cotton-wool spots on fundoscopic exam - May also occur with esophagitis - CD4+ < 50 cells/mm3 |
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Which pathogen causes non-Hodgkin Lymphoma (large cell type) in HIV-positive adults? Findings? Other?
|
May be associated with EBV
- Often on oropharynx (Waldeyer ring) |
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Which pathogen causes primary CNS lymphoma in HIV-positive adults? Findings? Other?
|
Often associated with EBV
- Focal or multiple - Differentiate from toxoplasmosis |
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Which pathogen causes squamous cell carcinoma in HIV-positive adults? Findings? Other?
|
HPV
- Often in anus (men who have sex with men) - Or in cervix |
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Which pathogen causes Superficial Neoplastic Proliferations of Vasculature in HIV-positive adults? Findings? Other?
|
HHV-8 (Kaposi Sarcoma)
- Do not confuse with Bacillary Angiomatosis caused by B. henselae - Biopsy reveals lymphocytic inflammation |
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Which pathogen causes interstitial pneumonia in HIV-positive adults? Findings? Other?
|
Cytomegalovirus (CMV)
- Biopsy reveals cells with intranuclear (owl eye) inclusion bodies |
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Which pathogen causes pleuritic pain and hemoptysis in HIV-positive adults? Findings? Other?
|
Aspergillus fumigatus
- Invasive aspergillosis - Infiltrates seen on imaging |
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Which pathogen causes pneumonia with a ground-glass appearance on imaging of lungs in HIV-positive adults? Lab findings? Other?
|
Pneumocystis jirovecii
- Especially with CD4+ < 200 cells/mm3 |
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Which pathogens cause pneumonia in HIV-positive adults? Findings? Other?
|
- CMV: interstitial pneumonia, biopsy shows intranuclear (owl eye) inclusion bodies
- Pneumocystis jirovecii: pneumocystis pneumonia, ground glass appearance on imaging - S. pneumoniae: generally with CD4+ >200 cells/mm3 |
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Which pathogen causes tuberculosis like disease in HIV-positive adults? Lab findings? Other?
|
Mycobacterium avium-intracellulare (aka Mycobacterium Avium Complex (MAC))
- Especially with CD4+ < 50 cells/mm3 |
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|
What are the types of prion diseases?
|
- Creutzfeldt-Jakob disease (sporadic form)
- Gerstmann-Sträussler-Scheinker syndrome (inherited form) - Kuru (acquired form) |
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|
What is the cause of prion diseases?
|
Conversion of normal (predominantly α-helical) protein termed prion protein (PrP-c) to a β-pleated form (PrP-sc) which is transmissible
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What accumulates in patients with prion diseases? Characteristics?
|
PrP-sc (β-pleated form of proteins)
- Resists protease degradation - Facilitates conversion of still more PrP-c → PrP-sc |
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|
What are the results of accumulation of PrP-sc in patient with prion diseases?
|
- Spongiform encephalopathy
- Dementia - Ataxia - Death |
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|
Which form of prion disease is sporadic?
|
Creutzfeldt-Jakob disease (rapidly progressive dementia)
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Which form of prion disease is inherited?
|
Gerstmann-Sträussler-Scheinker Syndrome
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Which form of prion disease is acquired?
|
Kuru
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