AIDS — Core Principles

Core Principles

AIDS, or Acquired Immunodeficiency Syndrome, is the advanced stage of infection caused by the Human Immunodeficiency Virus (HIV). HIV is a retrovirus that primarily attacks and destroys CD4+ T-lymphocytes, which are crucial cells of the immune system.

The virus uses an enzyme called reverse transcriptase to convert its RNA genome into DNA, which then integrates into the host cell's DNA. This leads to a progressive decline in CD4+ T-cell count, severely weakening the body's ability to fight off infections.

Transmission occurs mainly through unprotected sexual contact, sharing contaminated needles, and from mother to child. Symptoms can range from flu-like illness in the acute phase to a long asymptomatic period, eventually leading to opportunistic infections and certain cancers when the immune system is severely compromised (AIDS stage).

While there is no cure, antiretroviral therapy (ART) effectively manages HIV, suppresses viral load, and prevents progression to AIDS, allowing individuals to live healthy lives. Prevention focuses on safe practices and medication like PrEP and PEP.

Important Differences

vs HIV (Human Immunodeficiency Virus) vs. a typical DNA virus (e.g., Herpes Simplex Virus)

Aspect	This Topic	HIV (Human Immunodeficiency Virus) vs. a typical DNA virus (e.g., Herpes Simplex Virus)
Genetic Material	RNA (single-stranded, diploid)	DNA (double-stranded)
Replication Strategy	Retroviral; RNA to DNA via reverse transcriptase, then DNA integration into host genome.	DNA to DNA replication, typically in the nucleus, without reverse transcription.
Key Enzymes	Reverse transcriptase, integrase, protease (all viral-encoded)	Host cell enzymes primarily, sometimes viral DNA polymerase
Target Cells	Primarily CD4+ T-lymphocytes, macrophages	Epithelial cells, neurons (specific to the virus)
Latency	Provirus integrates into host genome, can remain latent for years.	Viral DNA can exist as an episome or integrate, but the replication cycle is generally more direct.
Immune Evasion	High mutation rate (due to reverse transcriptase error-proneness), latency, immune cell destruction.	Latency, interference with antigen presentation, specific viral proteins.

The fundamental difference between HIV and a typical DNA virus lies in their genetic material and replication strategy. HIV, as a retrovirus, uses an RNA genome and a unique enzyme, reverse transcriptase, to convert its RNA into DNA, which then integrates into the host's genome. This integration leads to a persistent proviral state and allows for long-term latency. In contrast, typical DNA viruses directly replicate their DNA genome, usually within the host cell nucleus, without the need for reverse transcription. HIV's high mutation rate and ability to destroy immune cells also distinguish its pathogenesis.