Influenza Flashcards
Influenza virus causes a/n Acute/Persistent/ Latent/Slow Virus Infection
Influenza virus causes an Acute Infection
Structure of Influenza Virus:
Segmented genome of negative single strands of RNA
Enveloped virus
Neuraminidase (NA)
Haemagglutinin (HA)
HA is required for entry of virus into cells via binding to cell surface receptor/s.
NA is required for virus exit, and is the target for anti-viral drugs.
2 Other Surface proteins:
Matrix - M1
Ion Channel - M2
Virion Interior Proteins:
PB1, PB2, PA, NP
PB1, PB2, PA: Make up “replicase” RNA-dependent RNA polymerase
Influenza Virus Life Cycle:
Virus recognises Sialic Acid (A carbohydrate on the cell surface of nearly all cell types)
Endocytosis of virus
Escapes from endosomes through fusion, releasing virus into cell cytoplasm
Viral protein translocates to nucleus and starts making mRNA which is then translated by cell ribosomes, replicating more virus genomes.
Budding of new viruses through cell membrane.
Influenza Virus Replication is prone to mutations
TRUE OR FALSE
TRUE
Allows variations
Influenza Virus needs to convert its negative RNA strand to a positive RNA strand.
TRUE OR FALSE
TRUE
Virus proteins can steal mRNA caps/polyA tails in order to protect the Viral RNA
TRUE
Prevents recognition of viral RNA as being foreign
Replication of viral RNA
Takes host mRNA Cleaves and steals its 5’ end
Uses this 5’ end to copy the negative strand viral RNA into positive strand viral RNA
PB1 holds negative strand
PB2 steals 5’ end
HA trimer:
Globular head, binds to cell surface receptor
C-terminus stalk embedded in membrane
Protease cleavage site in stalk region
Antigenic shift:
Process by which two or more different strains of a virus combine to form a new subtype having a mixture of the surface antigens of the two or more original strains
Influenza vaccine production occurs in eggs
TRUE OR FALSE
TRUE
Cleavage of protease cleavage site in stalk region of HA trimer leads to generation of BLANK
Cleavage of protease cleavage site in stalk region of HA trimer leads to generation of fusion peptide.
Fusion peptide inserts itself into cell membrane of endosome, driving fusion.