Processing of Viral pre-mRNA Flashcards
Viral mRNAs are synthesised by either viral or cellular enzymes, and may be made in the nucleus or cytoplasm
How is mRNA then modified before translation?
Splicing occurs to what is known as pre-mRNA, to make functional mRNA
Short coding sequences (exons) are joined together to form full functional mRNA
The intervening sequences (introns) are discarded
Alternative splicing of viral pre-mRNA can regulate viral gene expression
Where does RNA translation occur
Ribosomes in the cytoplasm
What is the function of cellular micro-RNAs?
Cellular micro-RNAs may inhibit or facilitate reproduction of a variety of viruses; virally encoded miRNAs may promote viral replication, persistence, or latency or inhibit the host response
viral mRNAs can block export of host mRNAs from the nucleus
What effects can this have?
allows viral mRNA to utilise host machinery, and reduces competition from host mRNA
Inhibits host anti-viral response - reduced mRNA from nucleus means anti-viral proteins cannot be produced
What is RNA interference?
Also known as RNA silencing
Act as post-transcriptional gene regulation - can switch on or switch off genes, to help dictate which proteins are made
small RNA molecules that function in antiviral defence or regulate gene expression.
siRNAs - small interfering RNAs
miRNAs - micro RNAs
What is RNA interference?
Also known as RNA silencing
Act as post-transcriptional gene regulation - can switch on or switch off genes, to help dictate which proteins are made
small RNA molecules that function in antiviral defence or regulate gene expression.
siRNAs - small interfering RNAs
miRNAs - micro RNAs
What are benefits to virus of producing siRNAs and miRNAs to affect the host cell?
Inhibit viral defense
Establish latency eg herpesviruses
Promote viral replication over cellular protein production
Promote oncogenesis
