Question

Compare and contrast gene expression by influenza virus with that of + RNA viruses and other – RNA viruses.

Answer 1

• Plus strand virus are those in which the Rna itself acts like an mRNA and produces expression once it infects the host cells.
• But in - strand viruses like influenza virus , RNA has to be converted to plus strand mRNA and then gene expression takes place.
• In plus strand viruses , have ribosome binding sequence which makes host ribosoems to bind to this without recognition of 5' capped structure. Thus , protein synthesis takes place.
• In minus strand viruses, the virus capsid itself contains RNA polymerase which converts to plus strand .
• Once , it enters the cell, host cell machinery is directed to perform viral replication. Here host cell replication and gene expression stops.
• In minus strand virus like influenza virus, the 5' cap of the mRNA is removed by viral endonuclease and the viral mRNA gets attached to it . So, whenever the host cell is replicated , the viarl genome is also replicates because the virus uses host cell mRNA as its template.
• The influenza virus unlike other viruses (+ and -) have unusual splicing which makes them to take several forms.