Influenza Flashcards
what was influenza predicted to be
a cause of major pandemic for humans
what is one of the advantages of influenza viruses
ahead of the curve of vaccination against the virus
what type of virus is influenza
RNA
what are the types of influenza
A, B and C
where is RNA found in viruses
within the nucleic acid
what are the key stages of viral replication for influenza virus
attachment
penetration
uncoating
synthesis of viral components
assembly
release
how can influenza be transmitted
from person to person through large respiratory droplets, direct contact or airborne dispersal
where does infection from influenza mainly take place in the human body
respiratory tract
what does the initial stage of influenza infection look like
- attachment of virus proteins to a receptor on the surface of the host cell
- virus is then taken into the cell by receptor mediated endocytosis
- internalised in a membrane bound capture vesicle that carries the viral core
how does the virus get to the nucleus of the cell once it has been internalised
- travels along the microtubules with the help of kinesins
how does the capsid of the virus become decoded
the membrane of the vesicles fuses with the membrane of the virus to decode the capsid. the viral core RNA and proteins are then released into the cytoplasm and are guided by host proteins to the nucleus of the host cell.
how do the viral core proteins and RNA enter the nucleus
guided to the nucleus by host proteins and enter via host protein channels
what happens once the RNA and proteins of the virus have entered the host cell nucleus
cell machinery is used to replicate the viral genome to make mRNA. some will exit the cell to exploit cellular ribosomes to direct synthesis of viral proteins which go back to the nucleus to associate with viral RNA
what happens once the viral surface proteins are made
they are processed in the cytoplasm and travel to the cell surface where they combine with encapsulated nuclear proteins to form progeny viruses which depart from the cell by budding
how do the progeny viruses exit the cell
budding
how do vaccines work to prevent influenza
they stimulate host cellular responses to ingest the virus but are ineffective against viruses that cause the common cold and AIDS
what is hemagglutinin
one of the proteins on the influenza virus envelope
how does the virus attach to the host cell
haemagglutinin binds to the host receptor with sialic acid because it recognises the receptor polysaccharides that terminate with the sialic acid
how does the cell take up the virus
endocytosis
what does the endocytic vesicle of the virus fuse with and what are the events following this
lysosome, and the acidity within the lysosome allows protons to travel across ion channels into the viral core and cause matrix proteins to detach the proteins covering the RNA genome. haemogglutinin undergoes conformational change and inserts into the vesicle membrane to stimulate the membrane fusion between the virus and lysosome. the genome and proteins then flow freely away into the cytoplasm
how many RNA segments are within the influenza virus
8
how does the viral genome enter the host nucleus
nuclear pores
what is haemagglutinin
a glycoprotein composed of sugars and proteins which binds to sialic acid on the surface of cells.
how many types of haemagglutinin are there
14
