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20 Cards in this Set

  • Front
  • Back
Explain why an Orthomyxovirus genome should be a character on Grand Theft Auto
Enveloped virus with 8 negative sense RNA genome segments that replicates in the nucleus and steals host 5’ capped termini of cellular mRNAs as primers for viral mRNA transcription
What is the function of the Orthomyxovirus protein HA?
HA, the hemagglutin (vaccine target) binds to sialic acid (N-acetyl neuraminic acid) present on cell surface molecules
What is the function of the Orthomyxovirus protein M2?
M2 is a tetrameric integral membrane protein which forms an ion channel (target of anti-influenza drugs amantidine and rimantadine)
What are the types of influenza virus and how do they differ?
Influenza type A, B, and C (contain different M and NP antigens and have different RNA sequences at the ends of their genome sequences)
Who are the hosts of Influenza A?
Influenza A: humans, birds, horses, pigs, etc. (large reservoir in animals). Cause flu epidemics
Who are the hosts of Influenza B?
Influenza B: humans
Which Influenza causes epidemics?
Influenza A causes epidemics
Why are endosomes relevant to Orthomyxovirus replication?
Low pH in endosomes stimulates conformational change of HA glycoprotein and causes fusion of viral envelope with endosome membrane
What is Antigenic Shift
A drastic change of multiple antigenic domains of HA or NA in an influenza virus, often associated with pandemics. Occurs as a result of the segmented genome of flu virus and the re-assortment of the viral genomes in the large animal reservoirs of the virus (unique to Influenza A because it is maintained in large animal reservoirs)
What is Antigenic Drift
Random process that occurs as a consequence of the mutations introduced by the viral RNA dependent RNA polymerase during replication
What is the special problem of “Original antigenic sin?”
The immune response to the first infection with a virus having a dominating influence on subsequent immune responses
Why is effective vaccination against flu difficult?
Antigenic drift and antigenic shift render vaccination against flu difficult
What are two drugs are used in anti-influenza A therapy?
Amantadine and Rimantidine
What do Amantadine and Rimantidine target?
The M2 ion channel responsible for the alteration of pH required for viral uncoating and assembly
What are two recently approved neuraminidase inhibitors that can inhibit both influenza A & B viruses?
Relenza and Tamiflu
What is the pathogenesis of primary influenza infection
Short incubation period
No viremia
Interferons and cytokines cause fever, aches, edema
Stimulation of antibodies and virus-specific T cells
Immunity to re-infection mediated by IgA in respiratory tract
What are some of the complications of influenza
Primary influenza pneumonia
Secondary bacterial pneumonia
Encephalitis, pericarditis, myositis
Reye's syndrome (children given aspirin are at increased risk for this syndrome)
What is the basic structure of the Orthomyxoviruses
Large Enveloped RNA virus
SS negative RNA with 8 separate segments
Envelope derived from host cell membranes which contain viral glycoproteins HA and NA
Helical nucleocapsid
What promotes release of Orthomyxoviruses from the cell
NA, the neuraminidase
During Orthomyxovirus replication, what does viral polymerase use to prime viral mRNA synthesis
The viral polymerase steals caps from nascent host mRNAs and uses them to prime viral mRNA synthesis