Section 3 slides, Part 2

Section 3 slides, Part 2 - 10/12/11 1 Early Transcription...

Info iconThis preview shows pages 1–4. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: 10/12/11 1 Early Transcription Provirus DNA is transcribed making short mRNAs Regulatory proteins transcribed Translation of mRNAs into proteins Use of host cell ribosomes Early Shorter mRNAs First begins producing regulatory proteins (Tat, Nef and Rev) Translation Later Regulate shift from regulatory proteins to structural and enzymatic proteins. Larger mRNAs synthesized (Tat) and exported out of nucleus (Rev) ribosomes bind full-length RNA to make structural proteins (gag, pol and env). Role of Rev in HIV Lifecycle Important for translation Rev binds to the full-length HIV RNA Aids in long RNAs to exit nucleus Important for structural genes env , gag and pol Effects of Rev Full-length genomic HIV RNA in cytoplasm HIV genome Large mRNAs translated into structural genes and enzymes Capsid proteins, envelope proteins and viral enzymes would not be made Virus would not be assembled Other effects of Rev Necessary for Tat expression Acts like scorpion toxin on brain tissue 10/12/11 2 APOBEC3G Immune cells (T cells, e.g.) synthesize the enzyme APOBEC3G Has a powerful antiviral function APOBEC3G degrades viral RNA, impairing the viruses infectivity Induced mutations in viral genes make it impossible for new virions to be produced HIV Vif APOBEC3G incorporated into forming virions Vif localized to virion Regulatory protein - Vif destroys APOBEC3G so that it cant cause mutations in HIV genes in a newly infected cell counteracts APOBEC3G protective effect Both reduces the synthesis of and destroys existing APOBEC3G enzyme Processing of large proteins Three large polyproteins : gag, pol and env must be cleaved for functional virion gag matrix protein p17, capsid protein p24, and other smaller proteins pol the enzymes RT, IN and PR env the glycoproteins gp120 and gp41 Protease (PR) PR is on pol Autocleaves and released Cleaves other polyproteins Cytoplasm Inside maturing virion Essential for assembly and maturation of the virus Reduced function PR makes non- infectious HIV virions Release of virus Tetherin cellular restriction factor Vpu counteracts tetherin 10/12/11 3 Other Negative Effects of HIV Components Outlined in Reader Generally M = slow, low HIV production R5 viruses CD4+ T cells = rapid, high HIV production X4 viruses Linked to amount of CD4 expression Regulatory redux RT copies viral RNA into DNA vpr assists in carrying to nucleus IN inserts viral DNA into chromosome to form provirus LTR conversion to strong promoter T cell activation cytokines nef, vpr enhances NF B Enhanced RNApol activity full length transcripts tat RNA transcripts transported to cytoplasm rev Translation of structural proteins/assembly of new virus PR required, vpu utilized Treatment of HIV Disease Antiviral agents that attack the virus...
View Full Document

Page1 / 12

Section 3 slides, Part 2 - 10/12/11 1 Early Transcription...

This preview shows document pages 1 - 4. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online