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91 Cards in this Set
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What are the four paramyxoviridae viruses that cause human disease? |
1) parainfluenza virus
2) respiratory syncytial virus 3) mumps virus 4) measles (rubeola) virus |
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Which virus causes croup?
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Parainfluenza virus causes croup, which is an infection of the larynx and other upper respiratory structures (laryngotracheobronchitis). It occurs in children, and swelling of the structures produces airway narrowing.
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What is the number one cause of pneumonia in young children, especially infants less than 6 months?
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Respiratory Syncytial Virus (RSV). It lacks HA and NA but has an F-protein that causes formation of multinucleated giant cells (syncytial cells).
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What are the orthomyxoviruses?
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Influenza A (animals + humans-causes pandemics) , B (humans only), and C (humans only)
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What are some characteristic attributes of Measles?
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1. Prodrome: high fever, hacking cough and conjunctivities
2. Koplik's spots: small red based blue and white centered lesions in the mouth 3. Rash: from head, then to neck & torso, then to feet |
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What is antigenic shift?
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The formation of new viruses strains via the combination of human and animal viruses that co-infect the same cell. This can only occur with influenza A in orthomyxoviruses. New HA or NA glycoproteins are formed in the new strain.
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What is the difference between orthomyxoviruses and paramyxoviruses?
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Structurally
1. Paramyxoviridae's negative stranded RNA is single and not segmented 2. HA and NA are on the same glycoprotein spike in Para instead of different ones in Ortho 3. Para possess fusion (F) protein 4. Ortho - 100 nm, Para - 150 nm |
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What is Antigenic drift?
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Small changes in the HA or NA during viral replication through mutational changes.
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What two glycoproteins are responsible for the virulence of Orthomyxoviruses (influenza viruses)?
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1. Hemagglutinin (HA) - binds to sialic acid receptors on the surface of erythrocytes and
2. Neuraminidase (NA) - cleaves neuraminic acid , an important component of mucin, the substance covering mucosal epithelial cells, which forms an integral part of the host's upper respiratory defense barrier. |
NA cleaves neuraminic acid and disrupts the muin barrier, exposing th sialic acid binding sites beneath for HA to bind to.
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What are the DNA Viruses?
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Remember HHAPPP(y):
Herpes Hepadna Adeno Papova Parvo Pox |
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Which liver viruses are transferred via the fecal-oral route?
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A (anus)
E (enteric) |
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Only one of the hepatic viruses is a DNA virus. Which one is it?
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Hepatitis B. This virus lives in all human body fluids (urine, semen, saliva, blood, breast milk...). The intact virus is called the Dane particle at 42 nm. It has ds DNA.
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What are common symptoms of viral hepatitis?
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jaundice, painful enlarged liver, high blood levels of liver function enzymes (AST, ALT, GGT, bilirubin)
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Which hepatic viruses are transmitted parenterally?
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B,C,D,G (blood-to-blood/fluid-to-fluid transmission, e.g. sex, blood transfusion, across the placenta etc.)
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In the context of viral hepatitis, an increased IgG is indicative of what duration of disease?
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Old disease
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In the context of viral hepatitis, an increased IgM is indicative of what duration of disease?
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Acute disease
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In the context of viral hepatitis, if a patient tests positive for HBsAg and positive for HBeAg, what does that tell you about the disease?
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The disease is active (HBsAg) and quite virulent (HBeAg+).
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In the context of viral hepatitis, if a patient tests positive for Anti-HBsAg and positive for Anti-HBeAg, what does that tell you about the disease?
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The disease is cured, and the patient is immune (Anti-HBsAg), and the infection is old (Anti-HBeAg)
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This hepatic virus requires co-infection in order to have its virulent effect. What is the name of the virus and its coinfectant?
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Hepatitis D and B
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a) This proportion of patients infected with acute hepatitis C viral infection will develop chronic hepatitis
b) " " will develop cirrhosis |
a) 50%
b) 20% |
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HIV is which type of virus: DNA or RNA?
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HIV is a RNA reverse transcriptase virus with two RNA strands at its core. It has an icosahedral symmetric capid shell around the RNA dimer with capsid proteins. p24 capsid protein can be measured in the serum to detect early infection.
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What are the two surface glycoproteins of HIV?
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The surface glycoproteins are gp120 (head) and gp41 (stalk). They form gp160, which binds to the CD4 receptor on T-cells.
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It's difficult to generate a vaccine against HIV for many reasons, including one critical area of its genome that is highly variable. What is this region?
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The region of the env gene, particularly the area encoding the gp 120 glycoprotein has hypervariable regions where many point mutations and other mutations occur (including duplications and deletions).
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These two cell surface proteins serve as cofactors for the binding of HIV to T-cells.
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1) Fusin
2) CKR5 which are produced by T-lymphocytes and macrophages serve as co-factors with the CD4 molecule for binding of HIV to lymphocytes and macrophages. They are targets for new therapies. |
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Describe the acute viral stage of HIV illness:
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* mononucleosis symptoms (fever, malaise, lymphadenopathy, pharyngitis, etc.)
* high levels of blood-borne HIV (viremia) * virus spread to lymph nodes and macrophages An HIV-specific immune response then reduces the above symptoms. |
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What is the normal CD4+ T-cell count in humans?
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1000 cells/microliter of blood
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What is the CD4 T-cell count that defines AIDS?
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Aids is defined as having a CD4 T-lymphocyte count of less than 200 (with serologic evidence of HIV infection such as a positive ELISA or western blot test)
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This virus is the most common cause of viral encephalitis.
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Herpes Simplex Virus-1 (HSV-1)
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What are the TORCHES organisms that can cross the blood-placenta barrier?
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TOxoplasmosis
Rubella Cytomegalovirus HErpes, HIV Syphilis |
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What is the most common viral cause of mental retardation?
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CMV
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This virus is responsible for mononucleosis, the "kissing disease."
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Epstein-Barr Virus (EBV) is the most commonly associated virus with mono, but CMV can also cause a mononucleosis syndrome in young adults.
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Which portions of the liver produce AST and ALT?
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the hepatocytes
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What changes in the blood are indicative of a gallstone as opposed to viral hepatitis infection?
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First elevation of bilirubin due to blockage of duct, then rise in GGT and alkaline phosphatase (synthesis increased by canalicular cells) followed by rise in AST and ALT (minimally elevated)
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What disease is Poxviridae responsible for?
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Poxviridae used to cause smallpox, which has been ostensibly eradicated. Poxviridae is the most complex virus with a brick-shaped box, and it replicates in the cytoplasm, unlike all other DNA viruses.
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Name the top 4 viral respiratory illness causes in children, in order of frequency.
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1) RSV
2) Parainfluenza 3) Rhinovirus 4) Adenoviridae |
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What are the Arboviruses?
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bunyaviridae, togaviridae, reoviridae, and flaviviridae. They are all transmitted by blood-sucking arthropods and cause fever and encephalitis.
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This "break-bone" fever occurs in the tropics. What is its name and its symptoms?
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Dengue fever is a mosquito-borne febrile disease that occurs in the tropics. It causes painful backache, joint point, and severe headache.
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Which viruses cause the common "cold?"
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Rhinovirus and corona virus cause the common cold. About 15% are caused by coronaviridae. Also, adenovirus and RSV cause the cold.
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What are the viruses that cause death by diarrhea?
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1) Calciviridae
2) Norwalk virus 3) Rotavirus |
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What virus is the leading cause of bronchiolitis?
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RSV
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As far as antivirals go, what are the 3 neuraminidase inhibitors which would have an effect against which virus types?
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oseltamivir (Tamiflu), zanamivir (Relenza), & peramivir are neuraminidase inhibitors that would have an effect against influenza viruses
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In the antiviral category, name the M2 channel blockers and the virus or group of viruses they act against.
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adamantanes, e.g. amantadine & rimantadine are M2 channel blockers that work against influenza viruses
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How are HSV-1 and 2 viruses transmitted?
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Transmission by intimate contact--exposure of mucosal epithelia or damaged skin to oral or genital secretions
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1) Where does HSV-1 preferentially reactivate?
2) Where does HSV-2 preferentially reactivate? |
1) trigeminal ganglion
2) sacral ganglion |
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CMV-related illness is rare and only occurs in 2 groups. What are these 2 groups?
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1) The immunocompromised (e.g., AIDs patients)
2) Fetal infections (transmitted from the mother) |
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Are viruses metabolically active outside the cell?
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As obligate intracellular parasites, viruses are metabolically inert outside the cell.
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What is an abortive infection?
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An abortive infection is when viral genes are expressed, but infectious progeny do not result (cell probably dies)
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Does viral replication occur during a latent infection?
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No. Replication does not occur, but the cell remains viable, although it may be altered in function.
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How can a cell be resistant to a virus?
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A cell is resistant to viral infection if it lacks the receptors for viral entry.
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What is the eclipse period in the viral replication process?
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The eclipse period is when the virus has disassembled, and there is active viral gene expression and genome replication, before enough viral genomes and structural proteins for assembly of new virions.
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What’s the advantage of having an envelope for viruses?
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The advantages of a membrane/envelope as opposed to a protein, you don’t have structural requirements, so you can have more specificity in your host range.
Protein coats restrict the geometrical structure, and you can’t change the protein structures much. |
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What’s the drawback to having an envelope for viruses?
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A virus with an envelope on the outside is very susceptible to environmental stress
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Replication is compatible with cell survival for which two virus families?
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Usually replication means the death of the cell, but for Hepadnaviruses and Retroviruses, it is compatible with cell survival.
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What is HA, and to what does it bind?
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HA (hemaggluttinin) is a surface glycoprotein on the envelope of influenza viruses, and it binds to sialic acid on the cell surface glycoproteins and glycolipids and induces fusion between the virion envelope and cell membrane. Before HA can do anything, it must be cleaved by tryptase clara, which is only present on respiratory epithelia.
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What is NA, and what does it do?
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NA (neuraminidase) cleaves sialic acid from cell glycoproteins and glycolipids.
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Why is rotavirus such a successful enteric pathogen?
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Rotavirus is a successful enteric pathogen in part because it is resistant to low pH and actually relies on proteolysis to enhance infection of villi in the small intestine.
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Which viruses cause the human cold?
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Adenoviruses, Rhinoviruses, Coronaviruses, and RSV
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Why do humans keep catching the cold?
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There are over 100 serotypes of Rhinoviruses, and although you may generate immunity to one, there are several others that can infect. RSV doesn’t cause a durable immunity within your self. As a result, it can infect you over and over again (he says it’s in some ways analagous to HIV).
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What are the re-infection capabilities of Parainfluenza virus?
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Since there are only 4 human parainfluenza viruses (HPIV 1-4), and you can only get infected by each one once, and you get infected by them mostly as a child, by the time you’re an adult you have life-long immunity.
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Are enteric viruses enveloped?
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Enteric viruses are never enveloped.
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Which hepatic viruses do not have an envelope?
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Hepatitis A & E do not have envelopes
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How do the hepatitis viruses kill cells?
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The hepatic viruses are thought to be non-lytic, although they generate an immune response to viral antigens expressed in infected cells.
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What are viruses that sporadically cause hepatitis?
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1) Yellow fever (flavivirus)
2) Cytomegalovirus 3) HSV 4) Epstein-Barr virus 5) Enteroviruses (picornavirus) |
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What is the leading cause of cirrhosis worldwide?
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HBV
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How does the severity of hepatitis A infection vary with age?
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The severity of hepatitis A infection increases with age.
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Of the particles produced by HBV, which are the infectious particles?
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The Dane particles are infectious. Other particles made are decoys (e.g., sub-viral particles (SVPs) and HBsAg filaments
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Why does HIV use a retrovirus?
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HIV inserts a DNA copy of its retroviral genome into infected cells, because it would be more stable and ensure transmission of the proviral DNA to all daughter cells.
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Why doesn’t the immune system clear HIV?
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Infected cells have latent virus that does not produce viral antigens or have its genome transcribed and is thus invisible to the immune system. Also, the viral proteins carry a great deal of variability, which can evade the adaptive immune response. Furthermore, HIV is not very immunogenic (i.e., it does not produce a protective immune response).
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What is the composition of highly active anti-retroviral therapy (HAART)?
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HAART is composed of two nucleoside analogs and one protease inhibitor.
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What are the receptors on the CD4 + T cells that HIV uses to bind?
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CCR5 and CXCR4 chemokine receptors are used by HIV to bind to CD4 T cells
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What are the names and functions of the accessory HIV proteins?
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Tat regulates transcription and enhances viral gene expression
Rev regulates RNAs coming out of nucleus Vpr imports pre-integration complex into nucleus Vpu ubiquitinates CD4 in ER causing its destruction Nef removes CD4 and MHC Class I from cell surface Vif overcomes an innate cell defense that normally would block production of infectious virions |
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What are the arboviruses?
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Togaviridae, Flaviviridae, Bunyaviridae, Reoviridae
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What are the oncogenic viruses and their corresponding cancers they could cause?
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1) Papillomavirus, cervical cancer
2) Epstein-Barr virus, Burkitt’s lymphoma, nasopharyngeal carcinoma, B cell lymphomas in immunodeficient individuals 3) Human T-cell lymphotropic virus, Adult T cell lymphoma 4) HBV, HCV, HCC 5) Human herpesvirus 8, Kaposi’s sarcoma 6) Merkel Cell Virus, skin cancer (affects elderly and immunosuppressed individuals) |
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What viral proteins are required to induce cell proliferation in HPV infection of the cervical cells (to formulate the carcinoma)?
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E6 (binds to and enhances the degradation of p53) and E7 (binds to RB and prevents its normal activities). Both E6 and E7 are invariably expressed in cancer cells.
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What are the three serotypes of papillomavirus that are most frequently associated with cervical cancer?
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Serotypes 16, 18, and 31 of HPV are most frequently associated with cervical cancer.
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How is HPV transmitted?
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HPV is transmitted by direct contact with infected tissues or secretions.
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Can you describe the progression of cancer after infection of cervical cells by HPV?
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HPV induces proliferation of cells in the basal layer, but the viral genes are non-permissive (i.e., no progeny are produced). The infected cells differentiate and move to the surface and become permissive for virus production, and virus is shed from the surface.
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What percentage of human cancers are caused by virus?
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15%
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What receptors on B lymphocytes does EBV bind to?
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EBV uses receptors that may be related to the virus receptor on B lymphocytes (CR2, a receptor for C3d)
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What is the mechanism for EBV causing Burkitt’s lymphoma?
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EBV contributes to genetic instability, but it’s a translocation involving c-myc which turns on the proto oncogene that causes the carcinoma. (Also requires exposure to malaria and dietary deficiency)
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How long is the incubation period for HTLV?
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30-40 years
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What are the 8 different herpesviruses that infect humans?
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Alpha: HSV-1,2, Varicella-Zoster,
Beta: Cytomegalovirus, HHV6,7 Gamma: Epstein-Barr virus, HHV8 |
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Can vaccines be developed against the Herpesviruses?
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The Herpesviruses are antigenically stable, thus vaccines could be developed to prevent primary disease but may not be effective at preventing latency.
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What is the leading cause of infectious blindness in the developed world?
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HSV-1 is the leading cause of infectious blindness in the developed world.
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VZV and HSV are closely related evolutionarily, but what is a significant contrast between the two?
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VZV causes systemic disease, while HSV causes localized disease.
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What are the primary targets of EBV, and what receptors are necessary for the binding of the virus?
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B lymphocytes are the primary target of EBV, and interaction with two receptors is required: 1) CD21 (a complement receptor) and 2) MHC Class II molecules.
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What needs to be expressed by infected B cells in order for the T cells to kill them in the context of an EBV infection?
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LMP1 and EBNA
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How does acyclovir work for herpesviruses?
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Acyclovir is a GTP analogue. It stops DNA from elongating.
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Can you contrast properties of the alpha versus the beta herpesviruses?
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Alpha herpesviruses have a short reproduction cycle, and their latency site is the CNS. Beta herpes viruses have a long reproduction cycle, and their latency site is in the lungs/glands/kindeys.
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What percentage of adults are infected with CMV?
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90-95% of adults are infected with CMV.
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LMP-1 is important for EBV infection. What does it do?
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LMP-1 is an integral membrane protein required to protect the latently infected B cell from the immune response. LMP-1 is a critical protein involved in the proliferation of EBV in order for it to become immortalized.
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