During which stage of HIV infection do the symptoms of AIDS usually appear ?

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Correct — option (3). The whole point of this question is the distinction between being infected with HIV and having AIDS. HIV is the virus; AIDS, the Acquired Immuno Deficiency Syndrome, is the late clinical stage that follows once the virus has destroyed enough of the immune system. Trace the sequence the option set is built on. The virus enters the body and infects macrophages. Being a retrovirus, its genetic material is RNA, so it must first make a DNA copy of itself using its own enzyme, reverse transcriptase; that viral DNA is then inserted into the host cell's own DNA and turns the infected cell into a factory for new virus particles. The virus also enters helper T-lymphocytes, the cells that act as the master switch of the adaptive immune response, replicates inside them and releases progeny virus which goes on to attack still more helper T cells. Repeated round after round, this steadily drives down the number of helper T-lymphocytes in the body. It is only when that population has been depleted far enough that the person becomes unable to defend himself against organisms that would normally be harmless — and the bouts of fever, persistent diarrhoea, weight loss and opportunistic infections by bacteria, viruses, fungi and parasites appear. Those are the symptoms of AIDS. Every earlier step in the list is real, but silent. Note also how long this takes: the gap between infection and the appearance of AIDS is typically several years, commonly quoted as five to ten, and can run from a few months to many years.

Why the other options are wrong — (a) This is the very first event of the infection, and it produces no AIDS. Entry into macrophages and helper T cells starts the process; it does not end it. Some people do experience a brief flu-like illness within a few weeks of acquiring HIV, but that is a short seroconversion illness, not the syndrome the question is asking about, and it resolves. Confusing the moment of infection with the onset of disease is exactly the error the option is placed here to catch, and it is the same error that makes people believe a person who 'looks well' cannot be carrying HIV.  (b) Reverse transcription is a molecular event inside a single infected cell — the RNA genome of the retrovirus being copied into DNA so that it can be integrated into the host chromosome. It is the step that gives retroviruses their name and it happens within hours of the virus entering a cell, long before any immune damage has accumulated. A biochemical step inside one cell cannot produce a whole-body syndrome; symptoms require the loss of a large fraction of the helper T-cell population. This option is attractive because it is the most technical-sounding line in the set, which is precisely why it deserves suspicion.  (d) Wrong on the timing and wrong on the route. The interval between infection and the appearance of AIDS is typically measured in years, not days — a few months to many years, most often around five to ten. Fifteen days is in fact inside the 'window period', during which a newly infected person may still test negative on an antibody-based test while already being infectious. The option is also too narrow on transmission: besides sexual contact, HIV passes through transfusion of contaminated blood and blood products, through sharing of infected needles, and from an infected mother to her child through the placenta. Any option that fixes a short, precise deadline on a slow disease should be read twice.

Concept: HIV belongs to the group of viruses called retroviruses, which carry their genetic information as RNA and possess reverse transcriptase, an enzyme that copies RNA into DNA — the reverse of the usual flow of information in a cell. That DNA copy is spliced into the host cell's own genome, which is why the infection is lifelong: the viral instructions become part of the cell. The target that matters clinically is the helper T-lymphocyte. Helper T cells do not themselves kill infected cells or make antibodies; they instruct the cells that do. Removing them therefore disables the immune response broadly rather than against one germ, and that is what the word 'deficiency' in Acquired Immuno Deficiency Syndrome refers to. The illnesses that follow are called opportunistic infections because the organisms causing them — including mycobacteria, fungi and parasites such as Toxoplasma — take an opportunity created by the failed defence rather than being unusually virulent in themselves.

State PCS 2026 Q63 — Science & Technology PYQ with Answer

State PCS 2026 Q63 — Science & Technology PYQ with Answer