The HIV virus

Objectives

At the end of this session the participants will be able to:

1. Understand basic HIV structure2. Describe the significance of genetic

diversity and classification of HIV3. Describe the replication cycle of HIV4. Know the targets sites for ARV drugs

Host cellprotein

Ribonucleic protein (p24)

RNA with protein surround (p7/p9)

HIV structure

GP 120GP 41

RNA with

Protein Surroun

d

Nucleocapsid

HIV Replication Cycle

HIV particle

Injection of contents

HOST CELL

BindingBindingsites

RNA DNA

Reversetranscription Transcription

Integration of provirusDNA into host DNA

Translation

Cellmembrane

CompletedHIV particle

Maturation

Budding

Viralassembly

Proteincleavage

gp41 gp120

RNA s e

Protease

IntegraseProvirus(circularstructure)

HIV Particle CD4

Cell

1. Binding

2. Injection of Capsid Contents

3. Reverse Transcription

4. Translation

5. Viral Assembly

6. Budding

Mode of Action of ARV’s All ARV’s work by preventing

multiplication of the HIV particle They work at different stages of the

replication cycle If HIV cannot multiply, it is prevented

from destroying the CD4 Cells Detailed knowledge of the mechanism of

action of ARV’s is of academic interest, but it is not of great practical importance for prescribers

Targets of ARV drugs

HIV particle

Injection of contents

HOST CELL

BindingBindingsites

RNA DNA

Reversetranscription Transcription

Integration of provirusDNA into host DNA

Translation

Cellmembrane

CompletedHIV particle

Maturation

Budding

Viralassembly

Proteincleavage

gp41 gp120

RNA s e

Protease

IntegraseProvirus(circularstructure)

Protease Inhibitors work here

NRTI’s & NNRTI’s

work here

Fusion inhibitors work here

CD4 Cell

HIV Particle

Summary HIV is a retrovirus which kills CD4 cells

and so weakens the immune system Rapid replication of HIV causes genetic

diversity of the virus Knowledge of the HIV structure is

important in knowing the targets of ARV drugs

HIV enzymes are mostly the targets of ARV drugs

ARV’s do not cure HIV