HIV specifically targets Helper T-lymphocytes, also known as CD4+ T cells. These cells are crucial for immune response, as they play a central role in activating other immune cells, including B cells, cytotoxic T cells, and macrophages. CD4+ T cells help coordinate the immune system’s response to infections and cancer cells.
Once HIV enters the body, it binds to the CD4 receptor on these T cells using the viral spike protein, gp120. The virus also requires co-receptors such as CCR5 or CXCR4 to enter the cell. After fusion with the cell membrane, the virus releases its RNA into the host cell, where it is reverse-transcribed into DNA by the enzyme reverse transcriptase.
The viral DNA is then integrated into the host's genome by the enzyme integrase, where it is transcribed and translated to produce new viral proteins. These proteins assemble into new viral particles, which are released from the infected cell to infect more CD4+ T cells. Over time, the progressive loss of these critical immune cells severely weakens the immune system, making the individual vulnerable to opportunistic infections and cancers, a condition known as AIDS (Acquired Immunodeficiency Syndrome).
Antiretroviral therapies (ART) can help manage HIV infection by inhibiting the virus's ability to replicate, but there is no cure for HIV at present.