At which stage of HIV infection does one usually show symptoms of AIDS ?
- Within 15 days of sexual contact with an infected person.
- When the infected retro virus enters host cells.
- When HIV damages large number of helper T-Lymphocytes.
- When the viral DNA is produced by reverse transcriptase.
Answer
(3) When HIV damages large number of helper T-Lymphocytes.
Solution
As per NCERT, after getting into the body HIV enters macrophages, where its RNA genome is replicated to viral DNA by reverse transcriptase; the macrophages continue to produce virus (HIV factory).
HIV then enters helper T-lymphocytes (TH), replicates and produces progeny viruses, which attack other helper T-lymphocytes. This leads to a progressive decrease in the number of helper T-lymphocytes, and only then does the person start suffering from infections and show the symptoms of AIDS.
∵ There is always a time-lag between infection and appearance of AIDS symptoms (a few months to many years, usually 5–10 years), options (1), (2) and (4) are early stages without symptoms.
Answer: (3)