HIV Transmission Routes and Prevention — NEET Biology

Correct answer: C — S2, S4 and S5 only

The core concept tested here is the characteristic features of retroviruses, using HIV as a prime example, based on NCERT descriptions. S1: This statement is incorrect. Retroviruses, including HIV, possess an RNA genome, not a DNA genome. This RNA genome is reverse transcribed into DNA before integration into the host's DNA. S2: This statement is correct. Reverse transcriptase is an enzyme that synthesizes DNA from an RNA template, a process 'reverse' to conventional transcription. It is a defining feature of retroviruses and essential for their life cycle. S3: This statement is incorrect. While HIV primarily infects helper T-lymphocytes and causes immunodeficiency, the statement 'All retroviruses primarily infect helper T-lymphocytes' is an overgeneralization. There are other retroviruses that infect different cell types or cause other diseases. S4: This statement is correct. After the viral DNA integrates into the host's DNA, it directs the host cell's machinery to produce new virus particles, including viral proteins. S5: This statement is correct. Retroviruses, including HIV, are enveloped viruses, meaning their genetic material (RNA genome) is enclosed within an envelope. Therefore, statements S2, S4, and S5 are correct. This question assesses detailed knowledge of retroviral structure, enzymes, and replication, specifically in the context of HIV.