viral pathogens I Flashcards
how do viruses use the central dogma
replicate DNA/RNA
produce DNA/RNA
HIV
HIV = 2 copies of RNA, covered in protein and membrane
outer envelope consists of lipid bilayer protruding env spikes
inside envelope = gag proteins
MA associates within membrane CA, forms conical capsid NC coats viral RNA genome
core contains two genomic RNA strands, tRNA and 50 copies of each viral enzyme
what are the 3 polyproteins of HIV
- gag = group specific antigen, viral core proteins, MA, CA and NC
- pol = viral enzymes, proteases, reverse transcriptase, integrase
- env = envelope glycoprotein
HIV-1 features
env consists of a trimer of gp41 and gp120 peptide subunits and is covered with glycans
HIV-1 entry requires 2 membrane proteins - cd4 and chemokine receptor
what does CD4 do
recognises sequence within surface surface subunit gp0 envelope
what does viral integrase enzyme do
binds both host and viral DNA
what does LEDGF/P75 do
binds HIV-1 integrase and facilitates targeting to chromatin
describe how HIV promoter contains binding sites for TF that are present in T lymphocytes
binding of tat protein to TAR RNA enhancers elongation of RNA pol II
dimerisation of unspliced viral RNA allows packing of two genomes and movement
gag and gag-pol protein is generated by 1 ribosomal frameshifting = induced by slippery sequence and RNA hairpin structure
what does HIV-1 rev protein
mediates nucelar export of unspliced and singly spliced viral RNA
rev is essential for nuclear export of intron containing viral mRNAs
rev protein interacts with crm1 and the RRE RNA
what is HIV-1 PTAP motif
required for virus budding and mediates binding of the host tsg101 protein
what does ESCRT machinery
hijacked by HIV to perform membrane abscission during viral release
protease releases the individual proteins from gag and gag-pol polyproteins
gag processing generates mature virions
