Q.What is the mechanism by which the AIDS virus causes deficiency of immune system of the infected person?

The Human Immunodeficiency Virus (HIV) primarily targets helper T-lymphocytes, which are vital components of the body's immune system. Once inside the body, the virus enters these helper T-cells and replicates, producing numerous new viral particles. These newly formed viruses are then released and proceed to infect and destroy more helper T-lymphocytes.

This continuous destruction leads to a progressive decline in the total number of helper T-lymphocytes in the infected person's body. Since helper T-cells play a central role in coordinating the immune response, their depletion severely weakens the immune system. Consequently, the infected individual becomes highly susceptible to various infections, includi …

The Human Immunodeficiency Virus (HIV), the causative agent of Acquired ImmunoDeficiency Syndrome (AIDS), is a retrovirus. Its defining characteristic, and the key to its devastating effect, is its ability to systematically dismantle the body's immune system. It achieves this by specifically attacking and destroying a crucial component of our adaptive immunity: the helper T-lymphocytes, also known as T-helper cells or CD4+ T cells.

Upon entering the human body, HIV first seeks out and infects macrophages. These large immune cells, typically involved in engulfing pathogens and presenting antigens, become the initial breeding grounds for the virus. Inside the macrophage, the viral RNA genome undergoes a critical transformation: using an enzyme called reverse transcriptase, it synthesizes viral DNA. This newly formed viral DNA then integrates itself into the host cell's DNA. From this point, the infected macrophage begins to produce new virus particles, effectively turning into an "HIV factory."

These newly generated virus particles are then released from the macrophages and proceed to infect other vital immune cells: the helper T-lymphocytes. This is where the most significant damage occurs. Once inside a helper T-lymphocyte, the virus replicates rapidly, producing a multitude of progeny viruses. These new viruses are then released into the bloodstream, where they go on to attack and destroy even more helper T-lymphocytes.

This continuous cycle of infection and destruction leads to a progressive and severe decrease in the total number of helper T-lymphocytes in the infected person's body. Helper T-lymphocytes are central to coordinating the immune response; they activate other immune cells, such as B-lymphocytes (which produce antibodies) and cytotoxic T-lymphocytes (which kill infected cells). Without a sufficient number of these "command and control" cells, the entire immune system becomes severely compromised. …

Method: Compress the Mechanism into One Causal Chain

Instead of narrating the mechanism as a story, this method states it as a single linked

chain of cause and effect — useful for a quick recall or a "mechanism" mark in a marking

scheme that rewards each correct link.

HIV enters the body → infects helper T-lymphocytes (CD4+ cells) using reverse

transcriptase to convert its RNA into DNA → that viral DNA integrates into the host cell's

own DNA → the infected helper T-cell is hijacked into producing new HIV particles instead of

immune signals → the new viruses destroy that cell and go on to infect more helper T-cells →

helper T-cell numbers fall progressively over months to years → without enough helper T-cells

to coordinate B-cells and cytotoxic T-cells, the immune system can no longer mount an …