HIV life cycle Flashcards
NINE phases of HIV life cycle
1) Attachment - attaches to T cells
2) Fusion - fuses membranes releasing capsid
3) Uncoating - releases ssRNA (2 single strands)
4) Reverse transcription - Make DNA copy
5) Integration - ds viral DNA inserted into chromosome
6) Replication - occurs in membrane
7) Assembly - new viriod
8) Budding
9) Maturation - infectious
What does HIV infect
CD4+ T cells (produce cytokines and coordinate immune response)
Structure of HIV
cytoplasmic cell of gp41 interacts with HIV matrix protein p17.
What is a polypeptide precursor?
What are the 3 genes that code for these?
smaller proteins are generated by proteolytic cleavage. Allow for a more compact genome
1) GAG (group specific antigen, capsid and matrix)
2) POL (polymerase, reverse transcriptase, integrase)
3) ENV (envelope, gp120 and 41 attachment and fusion
How is the capsid formed?
1000 repeats of the p24 capsid protein organised in hexameters, dimers and a few pentamers
What tropism does HIV show
Initially infects macrophages (co-receptor CCR5) then changes to CD4+ cells (CXCR4)
How does the virus attach
Conformational change bends gp41 so its inserted into the membrane, brings them together. gp120 allows interaction with co-receptor
How does Enfuvirtide work?
Inhibits fusion process and prevents virus from entering cell, biomimetic peptide.
What are the THREE entry inhibitors?
1) gp120-CD4 binding - ibalizumab
2) gp120-co-receptor binding - maraviroc
3) gp41-mediated membrane fusion - enfuviritide
How does Raltegravir work?
Blocks active site not integrated into chromosome, targets integrate viral DNA complex in the PIC
GAG polyprotein
1) what does it do
cleavage by HIV protease results in release of matrix protein, capsid protein, protein NC and p6 (which plays a role in the initiation of budding)
Protease inhibitors
1) What is the structure of HIV-protease 1
2) Give an example
1) 99 aino acid homodimeric aspartyl protease
2) saquinavir - not cleaved by protease so they remain in the active site and block it
