HIV/AIDS - Skildum Flashcards
What is the classification of HIV?
Family: Retroviridae Genome: Two copies of (+) ssRNA Capsid: Icosahedral Enveloped with GP120 and GP41 Tropism: CD4+ T-Cells, monocytes, macrophages
What enzymes does the HIV virus carry with it?
Reverse Transcriptase
Integrase
Protease
Describe the HIV genome by size?
Small and Compact with genes encoded on multiple overlapping reading frames
What 4 genes are encoded in the HIV genome?
gag: 3 capsid proteins (p24)
pol: reverse transcriptase, protease, integrase
env: envelope glycoproteins gp120 and gp41
LTRs: integration sites that bind host transcription factors NF-kB, Sp1, TBP
Viral GP120 interacts with host…
CD4
Viral CP 41 interacts with host
CXCR4
What is the normal function of Stromal Derived Factor-1 (SDF-1)
Bind CXCR4 on lymphocytes and direct their homing to tissues
HIV-1 infected T-cells express env proteins on their cell surfaces. Why?
Binding of env to CXCR4 induces autophagy, which is a major cause of CD4+ T-Cell loss
After the HIV-1 envelope fuses with the host cell membrane, what are the steps of the life cycle of HIV-1?
Binding of HIV-1 envelope glycoproteins with host cell receptors and envelope fusion with plasma membrane
1) Genome uncoats
2) Reverse transcription of viral ssRNA → dsDNA
- takes place in cytosol
- two rounds of reverese transcriptase:
- 1) RNA → ssDNA, 2) ssDNA → dsDNA
3) Viral DNA migrates to the nucleus
4) Viral DNA integrates into host cell DNA
- via viral integrase enzyme
5) Expression of viral genes to make viral proteins & viral genomes
- Txn of both mRNAs that make capsid/envelope and full length RNA that will be packaged into new virus
- NF-KB (TF) activates/recruits RNA pol II for transcription of viral genome
6) Proteolytic processing of viral proteins
- cleavage of unspliced RNA done by viral protease
7) Assembly of viral particles & budding from host
After HIV integrates into the host genome to become a provirus, what enzyme produces HIV mRNA and genomic RNA?
Host RNA Polymerase II
What test is used to diagnose and confirm an HIV infection?
ELISA - looking for antibodies against p24 antigen
Western Blot
What tests is used to monitor patients with HIV?
CD4+ T-Cell Enumeration by Flow Cytometry
PCR for viral DNA (Research) or RNA (Clinically)
What is the goal of therapy for patients with HIV?
Reduce the level of circulating virus
In HIV, there is an inverse relationship between CD4 count and what in terms of disease progression?
HIV RNA copies
When a CD4+ T-cell is activated, what transcription factor is activated?
NF-kB
