Viruses Flashcards
Viruses use components of the cell membrane
as receptors
Adsorption involves
random collision, interaction between specific proteins on viral surface and specific receptors on target cell membrane
It is not necessary that just because a cell has the receptors which the virus detects, the virus can productively infect it.
Some viruses use
more than one host cell receptor (HIV)
Viruses usually infect a limited spectrum
of cell types
Most neutralizing antibodies are
specific for virion attachments proteins
HIV binds to receptor proteins
CD4+ as well as co receptors CCR5 OR CXCR4
Influenza virus receptor is
sialic acid. Hemagluttinin is the surface protein of the virus which binds to the acid
Entry can occur via two mechanisms
endocytosis or fusion of virus envelope with cell membrane.
Uncoating is where
the viral genome is released, lysosomes strip off the virus protein coat, and the virion can no longer be detected; known as the eclipse period
The low pH in the endosome causes a
conformational change in the HA, and allows fusion of the viral membrane with the endosomal membrane
For a non- enveloped virus, after receptor attachment,
the virus is taken up into the endosome, conformational changes to the viral structural proteins results in - formation of a pore in the endosomal membrane and viral RNA released into the cytoplasm
Viral replication involves 2 steps
Assembly - may take place in cell nucleus, cytoplasm or plasma membrane
Release - sudden rupture of cell (non - enveloped viruses)…
Virus Budding is driven by
virus protein interactions
Packaging influences RNA
into virions
HIV maturation is driven by
virion protease, and only mature HIV is infectious
