HIV virus

What is HIV virus?

HIV (Human Immunodeficiency Virus) is a retrovirus belonging to the Lentivirus subgroup. This group is characterized by causing slow-progressing infections with long incubation periods. HIV is a human T-cell lymphotropic virus, meaning it primarily targets T cells in the immune system.

There are two main types of HIV:

• HIV-1: The most common type globally.
• HIV-2: Primarily found in West Africa and is less aggressive compared to HIV-1.

Structure of HIV

• Core: HIV has a cylinder-shaped core (Type D) that houses its genetic material and enzymes.
• Enzymes: The core contains essential enzymes like reverse transcriptase, integrase, and protease.
• Envelope: Surrounding the core is an envelope embedded with viral-specific glycoproteins (gp120 and gp41).
• Genome: The genome is composed of two single-stranded RNA molecules of positive polarity.
  

Enzymes of HIV

It has 3 special enzymes:

• Reverse transcriptase
• Integrase
• Protease

HIV relies on these three critical enzymes for its life cycle:

• Reverse Transcriptase: Converts viral RNA into DNA.
• Integrase: Integrates viral DNA into the host's genome.
• Protease: Cleaves newly synthesized polyproteins to create mature viral proteins.

Targets of HIV virus

Through gp120 on its envelope, HIV virus attaches to two targets on cell surface before fusion.

• INITIAL TARGET:

CD4 receptor

(this receptor is found on helper T cells , mononuclear cells and macrophages.

• Second targets ( chemokine receptors):

1. CCR5 receptors (macrophages)
2. CXCR4 receptors ( Helper T cells)