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156 Cards in this Set
- Front
- Back
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Are helical viruses always enveloped?
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YES
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Where does RNA virus replication take place? what is the exception?
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Cytoplasm
exception: orthomyxovirus (influenza) |
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Where does DNA virus replication take place? what is the exception?
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Nucleus
exception: poxviruses (have their own RNA polymerase in coded in their LARGE genome) |
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How do DNA viruses package themselves?
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build a capsid and then stuff the genome in it
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How do RNA viruses package themselves?
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build a capsid around the genome
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What three things constitute cell permissiveness and help viruses get into the cell?
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stage of differentiation
mitotic activity transcriptional permissivity |
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What cancers are associated with Herpesviruses?
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Epstien-barr virus
HHV8: kaposi's sarcoma |
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Why may a cell want to cause tumor formation?
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1) to take control of cell cycle to make it always ready for DNA replication. They can use everything the cell makes to replicate their own DNA
2) If they can keep the cell dividing, they can live in the descendents |
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What cells make IFN-alpha? IFN-beta?
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alpha: peripheral blood mononuclear cells
beta: most cells These constitute IFN-1. They set up an antiviral state in cells they come into contact with. |
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What diseases can you use type 1 IFN to treat?
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chronic hep B and C, condyloma acuminatum (HPV), and AIDS related kaposi's sarcoma
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Where is Type 2 IFN (gamma) made?
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Immune cells (not like type 1) it stimulates memory cytotoxic T cells to kill viruses
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What cells are innate immune defenses?
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NK, PMN, eosinophils, basophils, monocytes, macrophages
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What cells may also present antigens to T-cells?
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macrophages, B-cells, and DC
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What do CD4+ T cells do?
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MHC class II recognizer
activates other immune response via lymphokines. Regulates B ccells and CD8+ |
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What do CD8+ T cells do?
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recognize MHC class I produced on the inside and precented on cells.
Kills via FAS and perforin and produces cytokines |
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What is the time course of immune defenses during an acute virus infection?
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1) IFN-alpha, beta, TNF-alpha
2) NK cell death 3) T-cell mediated death |
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How does CMV hide from T- cell destruction?
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it diminishes cell surface expression of MHC I molecules needed for T-cell recognition
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What are the positive strand RNA viruses?
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picornaviruses
flaviviruses togaviruses coronaviruses hep E calciciviruses |
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What are the three subgroups of picornaviruses?
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1) Rhinoviruses (common cold)
2) Enterovirus (Polio, coxsackie) 3) Hep A (GI entrance) |
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What is the structure for picornavirus family?
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naked (stable)
icosahedral nonsegmented |
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What are some significant details about the life cycle of +RNA picornavirus?
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1) no 5' caps, instead VPg protein
2) 5' untranslated region IRES that recruits ribosomes and prevents translation of cell RNA |
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How is Polio spread?
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1) fecal-oral (poor sanitation, shellfish)
2) respiratory route (multiplies in tonsils) |
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What diseases are caused by rhinoviruses?
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#1 cause of common cold
URTI (likes to replicate at 33) so it rarely spreads. Get a lot of colds because immunity is weak |
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What is the treatment for Rhinovirus? vaccine?
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SOL
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What is the path of Polio virus?
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enters the GI tract and travels through the BLOOD to the CNS where it effects motor neurons
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What is the treatment for polio?
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no antivirals
vaccine: Salk (inactivated) and Sabin (attenuated) |
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What is the presentation of non-polio enteroviruses (Picorniviridae)
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1) exanthem (rash)
2) aspetic meningitis (#1 cause) 3) aseptic encephalitis NO immunization |
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What does coxsackie A virus cause (Picornaviridae)
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Hand-foot-mouth disease
Herpangina No immunization |
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What does coxsackie B virus cause?
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Myopericarditis: inflammation of the myocardium that is unrelated to ischemia.
Usually self-limiting COMMON NO immunization |
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How is Hep A transmitted?
What disease does it cause? |
fecal-oral, food-borne outbreaks
mild fever, malaise, nausea, jaundice LIVER DAMAGE (high ALT) *Immunization available |
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What are the characteristics of the Flaviviruses?
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enveloped, positive strand RNA, icosahedral, nonsegmented
EXIT BY BUDDING |
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What are the flaviviruses that are arboviruses?
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1) St. Louis Encephalitis Virus
2) West Nile Virus 3) Yellow Fever Virus 4) Dengue Fever |
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What do WNV and SLEV cause?
Are humans dead ends? Vaccine? |
encephalitis
humans=dead ends No vaccine! |
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What does Dengue fever cause?
Are humans dead ends? |
Fever (1st time) then second infection is hemorrhagic fever, which may be lethal
humans=amplifying hosts No vaccine! |
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What does Yellow Fever cause?
Are humans dead ends? vaccine? |
hemorrhagic fever (may be lethal)
jaundice humans are amplifiers VACCINE for travelers |
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What does a hepatitis C infection cause? (+RNA)
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Chronic in 85%
hepatitis, cirrhosis, #1 reason for liver transplant, HEPATOCELLULAR CARCINOMA |
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What are the Togaviruses (+RNA)
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Rubella
Alphaviruses (EEV, WEV) enveloped, icosahedral, non-segmented |
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Are humans dead end hosts in WEV and EEV?
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Yes, spread via misquitos
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What does the Coronavirus cause?
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common cold, SARS (worsens in second week) *quarantine, travel resitrictions
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What are examples of Caliciviruses?
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Norwalk viruses
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Characteristics of Norwalk, Diseases caused
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HARDY, naked, icosahedral
transmitted person-to-person, food Gastroenteritis outbreaks, decontamiation is difficult |
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Hepatitis E
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acute hepatitis, limited to developing countries.
Sanitation |
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What are the four families of - strand RNA viruses?
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BORP
bunyaviruses orthomyxoviruses rhabdoviruses paramyxoviruses |
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What viruses are orthomyxoviruses?
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Influenza A, B, and C (determined by the following)
NP: nuclepprotein M1: matrix protein M2: ion channel** |
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What are the envelope proteins on orthomyxoviruses
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HA: hemagglutinin
NA: neuramidase |
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What is the use of M2?
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M2 pumps protons into the virion to lower the pH so they can uncoat and release from endosomes
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What is unique about orthomyxoviruses life cycle?
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nucleic acid synthesis occurs in NUCLEUS, so does genome replication
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In orthomyxoviruses, what facilitates the release of the virion from the cell? (egression)
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the removal of sialic acid by NA
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What is antigenic drift?
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point mutations in HA and NA to diversify influenza
*RDRP infidelity |
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What is antigenic shift?
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INFLUENZA A ONLY: major reassortment through mixing pots such as pigs etc. Segmented genome allows this.
Pandemics caused |
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Do HA and NA of the orthomyxoviruses cause a large immune response?
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yes, that is why antigenic shift and antigenic drift are pressured to cause diversity
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What caused the 1918 flu epidemic?
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reassortment
RDRP was more pathogenic |
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What months is the flue seasonal for? Is H1NI seasonal?
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Influenza is spread via aerosol droplets there fore wintertime (D, J, F, M) are the most frequent months. H1N1 is NOT seasonal and occurs in summer.
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M2 channel inhibitors
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amantidine and rimantidine
stop viral uncoating (early therapy) Influenza A (but not H1N1) |
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Neuramidase inhibitors
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Zanamivir and oseltamivir
inhibit viral release from infected cell stops SA from being clipped off by NA Influenza A AND B |
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Paramyxovirus
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Mumps
measles parainfluenza Respiratory Syncytial virus (RSV) Metapnuemonovirus |
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How is the life cycle of paramyxoviruses different from orthomyxoviruses?
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1) replicate in CYTOPLASM
2) do not steal caps from cellular mRNAs |
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What are the paramyxoviruses have good immunity? bad immunity? why?
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Good: measles, mumps
Bad: Parainfluenzas, Respiratory syncytial virus, and metapneumovirus Local infections produce weaker responses than systemic ones |
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Where does Mumps effect? Fatal?
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Parotitis and testicle (sterility)
low mortaliity |
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What does Measles (Rubeola) cause?
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Koplik spots, high fevers
may progress to pneumonia or encephalitis KILLS toddlers in africa |
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What do parainfluenzas (1,2,3) cause? They are paramyxoviruses!
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(Immunity is short-lived)
Croup (swelling of vocal cords) Common cold Bronchiolitis No Tx and no vaccine |
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What does respiratory syncytial virus cause?
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bronchiolitis (virus kills epithelial cells)
colds croup SEVERE CASES: chronic lung disease, prematurity, congenital heart dx of fetus |
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What is the antiviral treatment for severe cases of RSV?
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No vaccine
ribavarin passive immunization |
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Metapneumovirus (paramyxovirus)
What does it cause? |
bronchiolitis
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What are the characteristics of rhabdoviruses?
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enveloped, BULLET SHAPED, -RNA strand
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How is rabies spread?
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bites (shed into saliva)
aerosol (bats caves) |
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How do you treat Rabies?
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1) prophylaxis (local wound care, passive and active immunization)
2) pre-exposure vaccination |
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What is characteristic pathology of rabies?
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Negri bodies
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What are the Bunyaviruses?
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Hantavirus (Sin Nombre)
LaCrosse Virus |
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What is hantavirus pulmonary syndrome spread? what happens? BUNYAVIRUS
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Spread via deer mice aerosol of rodent poop.
Progressive, pulmonary edema due to replication in endothelial cells |
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What disease does LaCrosse virus cause?
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encephalitis
humans dead end hosts |
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Rotaviruses
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DS RNA virus
gastroenteritis of young children damages intestinal epithelium treat with fluids/electroyltes RotaTeq Vaccine (3 doses) |
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What are the general features of the retrovirus family?
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enveloped icosahedral, single stranded diploid positive strand RNA, comes with a reverse transcriptase
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Oncoviruses
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cause cancer in vertebrates (Human T-cell leukemia virus)
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Lentiviruses
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slow vurises that cause infections of the immune system (HIV, SIV, VINSA VIRUS)
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What two glycoprotines are encoded in the HIV envelope?
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Gp120 (VAP)
Gp41 (fusion protein) |
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HIV encoded enzymes
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Reverse transcriptase
ribonuclease integrase protease |
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Gp41's job in HIV
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mediates fusion of the virus to the cell plasma membrane
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Gp120's job in HIV
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binds CD4
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Receptors for HIV (3)
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CD4
CCR5 CXCR4 |
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How does RT work?
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1) RT makes (-) DNA from (+) RNA
2) Then makes (+) DNA matching strand 3) degrades RNA as DNA is made |
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What is present on reverse transcribed DNA?
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Long terminal repeats (LTR's)
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What is needed for DNA to become integrated into the chromosome?
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Integrase, LTR's
integration is nearly random |
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Gag protein
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cleaved into capsid (p24) by proteases
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Pol protein
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HIV: cleaved into PR, RT, and IN
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What makes an HIV particle infectious?
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processing of gag and pol polyproteins by virally encoded proteases
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Where did HIV 1 and 2 come from?
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2: SIV sm from primate to man W. Africa
1. SIV cpz trans species (3way) transfer |
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What cells express CCR5? CXCR4?
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CCR5= macrophages, memory T
CXCR4= effector T cells |
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What are the key indicators for speed of progression in HIV?
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virus load
CD4 count |
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What oppurtunistic infections are telling that an HIV infection has become AIDS?
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pneumocystis carinii
toxoplasma gondii retinal HMCV |
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What does Elisa test for?
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p24 (capsid)
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What does western blot test for?
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gp120
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What is HIV RNA PCR used for?
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detection of primary or neonatal infection that may be masked by maternal antibodes
*prognostic indicator, moniter therapy |
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How is HTLV transmitted? What does it target? What does it cause?
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Transmission: breast feeding, sex, blood
Infects: CD4+ T cells causes: leukemia/lymphoma, peripheral neuopathy (ALL RARE) TAX protein promotes malignancy no vaccine no tx |
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What type of genome do herpesviruses have?
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double stranded DNA (large)
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What viruses are alpha herpes viruses?
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HSV-1
HSV-2 Varicella-zoster virus |
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What viruses are beta herpes viruses?
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Human Cytomegalovirus
Herpes 6 Herpes 7 |
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What viruses are gamma herpes viruses?
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Epstein-Barr Virus
Kaposi's sarcoma virus (HHV8) |
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What is recognizable about Herpes structure?
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Tegument: a protein layer between capsid and envelope
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Where is the viral genome expressed in Herpes viruses?
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In the nucleus. The virus enters the cell by receptor mediated fusion (glycoproteins). There are intermediate-early, early, and late genes)
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What virus uses viral nucleotide kinase? What is it used for?
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Herpesvirus
Used to produce sufficient nucleotide substrates for virus replication. It phosphorylates nucleosides and nucleoside analogs |
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Which DNA polymerase is used by Herpesvirus?
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VIRUS DNA polymerase: works episomally (can replicate independently of host chromosome and has origin of replication.
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What leg of the immune system responds to Herpesvirus replication?
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T cells (cellular immune system)
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What is the spread/latency pattern of HSV-1?
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1) infects/replicates locally
2) infects sensory nerve endings 3) travels up axon to ganglion where it lays dormant 4) may travel down nerve ending to shed or re-infect |
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How does HSV-1 cause cell damage?
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epidermal destruction via cytopathic effects AND T-cell mediated cytolysis
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What are histopathologic signs of damage to cells by HSV-1?
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multinucleated giant cells
inclusions |
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What diseases do HSV-1 cause?
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1) primary gingivostomatitis
2) ocular herpes 3) herpetic whitlow |
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What diseases does HSV-2 cause?
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1) cold sores
2) herpes keratitis 3) herpetic whitlow 4) herpes encephalitis 5) genital lesions |
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How do you treat HSV-1
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acyclovir: inhibits DNA synthesis
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What are the demographics of Herpes Simplex Virus 2
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more common in women
worldwide decreasing in US |
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Where do genital HSV-2 lesions lay dormant?
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Spinal ganglia
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How has HSV-2 become resistant to acyclovir?
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mutated thymidine kinase (really only seen in immunocompromised people)
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What is unique about Varicella-Zoster in terms of epidemiology?
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NO asymptomatic shedding
little variation in genome |
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What is thought to cause herpes zoster?
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immunosuppression due to normal aging
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How is epstein-barr virus (gamma herpes virus) spread? Is it common?
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Spread via close contact "kissing disease". Is found world wide and is HIGHLY prevalent.
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What cells are targeted by EBV?
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Epithelium, then B-cells,they circulate to secondary immune sites and may be reactivated to infect epithelia again.
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What diseases does EBV cause?
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1) asymptomatic (most common)
2) inefctious mononucleosis 3) lymphoproliferative disorder 4) Cancers: B-cell lymphoma, African Burkitt's lympoma, nasopharygenal carcinoma |
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Is the mononucleosis caused by EBV monopostive or mononegative?
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monopositive: herterophile antibody is present!
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What diseases are caused by CMV?
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1) asymptomatic (usually)
2) monospot NEGATIVE mono |
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What are the risks of CMV to a fetus?
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birth defects
deafness, sight impairment, developmental abnormalities |
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How do you treat CMV?
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gancyclovir= nucleoside analogue
foscarnet= non-nucleoside analogue, directly inhibits viral DNA polymerase |
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What is caused by HHV6
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Roseola (exanthem subitum) fever and rash
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How is HHV6 spread? where does it lie dormant?
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It is spread via saliva (sheds here)
lies latent in T-cells and monocyte-macrophages |
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What does HHV7 cause?
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rarely disease, sometimes roseola
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What does HHV8 cause?
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kaposi's sarcoma
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What Herpes virus has the lowest seroprevalence? THIS IS UNIQUE!
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HHV8- kaposi's sarcoma associated virus
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Where does HHV8 infect?
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B-cells, endothelium, monocytes, sensory nerves (LATENT IN B CELLS)
*sheds in saliva |
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What diseases are caused by HHV8?
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Kaposi's sarcoma= endothelial tumor
B-cell lymphoma |
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What is unique about poxviruses life cycle?
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The virus makes all enzymes needed for DNA and mRNA replication and replication occurs in the cytoplasm
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What does poxviruses cause?
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1) molluscum contagiosum (skin nodules)
2) variola virus (smallpox) 3) vaccinia virus (vaccine) |
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Adenovirus (naked DNA virus) Life cycle
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Coxsackie adenovirus receptor and interactions with integrin
early and late genes |
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What diseases does adenovirus cause?
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URTI
epidemic keratoconjunctiviis pharyngoconjunctival fever infantile diarrhea |
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What is special about the papillomavirus and polyomaviruses
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Circular ds DNA (HPV, JC, BK)
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What disease is caused by BK polyomavirus?
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UTI
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What disease is caused by JC polyomavirus?
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CNS disease
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What layer of skin do the mature HPV shed from?
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horny layer
clear layer |
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What layer of cells are the late HPV genes expressed in? Particles are also formed here.
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granular layer
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What layer of cells are the early HPV genes expressed and DNA replication occurs?
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spiny layer
basal layer |
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What cytopathologic characteristics occur in an HPV infection?
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koilocytosis (halo)
large cells with fluid filled cavities and distorted nuclei |
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What does HPV E6 do?
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inhibits p53
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what does HPV E7 do?
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inhibits retinoblastoma tumor suppressor
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What types of HPV are associated with cancer? warts?
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cancer (cervical, head, neck)= 18, 16
warts= 11, 6 |
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What is guardasil made out of?
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composed of empty capsids of 4 high risk HPV
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What parvovirus is discussed? characteristics?
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B19 (smallest virus)
naked, icosahedral, ssDNA targets erythroid progenitor cells |
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What does B19 virus cause?
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There are two phases, the second is immunological: Ab-Ag complexs may deposit under skin
-Arthritis -Aplastic Crisis -Congenital infections (anemia, loss, edema) |
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What is congenital B19 disease called?
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5th disease
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What is Hep B's genome like?
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partially dsDNA: negative strand is smaller
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What does Hep B use as infectious cells? decoys?
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infectious: Dane particles
decoys: HBsAg |
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what causes the liver damage in Hep B?
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T cells
actual virus |
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What diseases are caused by chronic hep b?
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liver disease, hepatocellular carcinoma, and cirrhosis
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What is the treatment for Hep B
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INF-alpha
Entecavir Lamivudine Adefovir |
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What is the genome type of Hep D?
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circular, negative strand RNA (totally dependent on Hep B)
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What enzyme is required to complete hep D's genome synthesis
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HDV RNA-ribozyme
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How is hepD usually spread?
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IV drug use
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What happens when HDV and HBV are coninfected together?
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fulminant hepatitis (deathly)
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What happens during an HDV superimposed on chronic HBV? (superinfection)
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chronic hepatitis, cirrhosis, carcinoma
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