MP Board · Class 12 · Biology · Human Health and DiseasesName the causative agent of AIDS and explain how it damages the host's immune system.

Acquired Immuno Deficiency Syndrome (AIDS) is caused by the Human Immunodeficiency Virus (HIV), which is a retrovirus possessing an RNA genome enclosed in an envelope. Upon entering the human body, HIV infects macrophages and helper T-lymphocytes ($T_H$ cells). Inside these cells, the viral RNA replicates to form viral DNA using the enzyme reverse transcriptase. The virus multiplies and progressively destroys helper T-cells, leading to a drastic decrease in their count, which severely weakens the host's immune system and makes it susceptible to opportunistic infections.