Notes

Human Retrovirus

• HTLV1

• HTLV2

• HIV-1, HIV-2

o HIV-2 less virulent

• Human foamy virus

• Human placental virus

• Human genome virus

HIV

• Retrovirus

• Enveloped

• + sense

• 2 ssRNA, 3 enzymes in genome

• Classified into types, groups, subtypes based on genetic similarities

o M (major) group

o O (outlier) group

o N & P (new) group

• Highly variable virus – mutates very readily

o High error rate of reverse transcriptase

o High replication rate of virus in vivo

• Destroy cells of immune system → immunosuppression

• Infect cells with CD4+ receptor (T-helper, macrophage, DC)

↓

Destruction through:

o Direct viral killing of infected cells

o ↑ rate of apoptosis of infected cells

o CD8+ T-cells mediated apoptosis

Susceptible Cells

• T-helper cells

• B lymphocytes

• Macrophages

• Dendritic cells

• Neurons

HIV Receptors

• CD4 on T-helper

• CXCR-4 chemokine receptor (used by T-cell tropic HIV strain)

• CCR-5 chemokine receptor (used by macrophage-tropic HIV strain)

CCR-5 Co-receptor Function

• Attachment

o gp120 bind to CD4 T-cell → conformational change

• Binding to second receptor

o Gp120 bind to CKR5

• Fusion

o Fusion peptide from gp41 exposed

o Viral and cell membrane fuse

Structure

[pic]

• Structural proteins

o gag – structural capsid proteins

o env – envelope glycoproteins

• Catalytic protein (yg biji2 kt tgh pic)

o pol – reverse transcriptase & viral integrase

• Regulatory proteins – tat, rev

• Accessory proteins – vpu, vif, vpr, nef

Production of DNA

• 2 ssRNA → dsDNA

• DNA is longer due to terminal repeats

• Reverse transcription...