Host RNA polymerase II (RNA pol-II) is the major enzyme responsible for transcription of mRNA from a DNA template strand.
Some viruses interfere with host RNA pol-II function. They may either mediate its ubiquitination and subsequent proteasomal degradation, or inhibit RNA pol-II phosphorylation thereby lowering its efficiency. They can as well interfere with initiation factors. Inhibiting host transcription eventually leads to shutoff of host proteins expression and gives viruses transcripts a competitive edge for access to the cellular translation machinery. Preventing the expression of host proteins is also a strategy to counteract the antiviral response.
Viruses inhibiting transcription:
|Family||Virus||Viral protein||Transcription inhibition strategy||references|
|Herpesviridae||HHV-1||ICP22||Counteracts CTD Ser-2 phosphorylation|
|Bunyaviridae||Bunyamwera virus||NSs||Counteracts CTD Ser-2 phosphorylation|
|Orthomyxoviridae||Influenza virus||Polymerase PB1, PB2, PA||RNA pol-II ubiquitination and proteasomal degradation|
|Papillomaviridae, alphapapillomavirus||HPV16||E7||Inhibition of TBP|
|Picornaviridae||Poliovirus||3C||Cleavage of TBP|
|Bunyaviridae, Phlebovirus||Rift valley fever virus||NSs||Downregulates TFIIH subunit p62|
|Herpesviridae||Varicella virus||IE63||Disruption of the transcriptional pre-initiation complex|