How does HIV integration into a helper T cell’s DNA affect the immune system?

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Diagram illustrating the process of retrovirus infection and reverse transcription, showing a retrovirus entering a host cell, releasing viral RNA, reverse transcriptase converting RNA to DNA, integration into the host genome, transcription of new viral RNA, assembly of new virions, and budding from the cell. — Reverse transcriptase After a retrovirus infects a cell, an enzyme known as reverse transcriptase converts viral RNA into proviral DNA in the cytoplasm. Proviral DNA then enters the nucleus, where it is incorporated into the host cell's DNA.

When HIV integrates its genetic material into a helper T cell’s DNA, it establishes a permanent infection within that cell. This integration is a critical step in the viral life cycle, allowing the host cell to function as a factory for producing new viral particles.1

The impact on the immune system is profound:

Loss of Immune Coordination: Helper T cells are essential for activating other immune components, including B lymphocytes (which produce antibodies) and cytotoxic T lymphocytes (which kill infected cells). As HIV destroys these helper T cells, the body loses its ability to coordinate an effective defense against pathogens.1
Viral Replication and Evolution: Because the viral enzyme reverse transcriptase lacks proofreading capabilities, the virus mutates rapidly. This allows HIV to evade both the immune system and antiretroviral treatments.1
Systemic Decline: The rate at which the virus destroys helper T cells eventually outpaces the body’s ability to produce new ones. This depletion, measured by a declining CD4 count, characterizes the progression of AIDS, leaving the host highly vulnerable to opportunistic infections.1