Give me 10 hiv microbiology mcq based on pyqs of neet pg

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HIV microbiology NEET PG previous year questions MCQ

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I now have solid data from authoritative medical textbooks to construct 10 high-quality HIV microbiology MCQs based on actual NEET PG PYQ patterns. Here they are:

10 HIV Microbiology MCQs - NEET PG Style (PYQ-Based)

Q1. HIV belongs to which family and genus?

A) Flaviviridae, Hepacivirus B) Retroviridae, Lentivirus C) Herpesviridae, Betaherpesvirus D) Orthomyxoviridae, Influenzavirus

Answer: B - Retroviridae, Lentivirus

HIV-1 and HIV-2 belong to the family Retroviridae and the genus Lentivirus. The defining feature is the presence of reverse transcriptase, which converts the (+) RNA genome into double-stranded DNA. The virion carries TWO copies of its (+) sense RNA genome, making it diploid.

Sherris & Ryan's Medical Microbiology, 8e

Q2. The envelope glycoproteins on the surface of HIV-1 are:

A) gp120 and gp41 B) gp160 and gp41 C) gp120 and gp160 D) gp46 and gp21

Answer: A - gp120 and gp41

The precursor gp160 (encoded by the env gene) is cleaved by a cellular protease into two surface glycoproteins: gp120 (surface unit, SU) and gp41 (transmembrane unit, TM). gp120 binds CD4 on target cells; gp41 mediates fusion. These form lollipop-like trimer spikes on the virion surface.

Jawetz Melnick & Adelberg's Medical Microbiology, 28e

Q3. HIV enters host cells by binding to the primary receptor CD4. The co-receptors used for entry are:

A) CCR3 and CXCR3 B) CCR5 and CXCR4 C) CCR2 and CXCR5 D) CCR1 and CXCR2

Answer: B - CCR5 and CXCR4

After gp120 binds CD4, a conformational change exposes the V3 loop, which then binds a chemokine co-receptor - either CCR5 (on macrophages, Langerhans cells, mucosal T cells) or CXCR4 (on naive T lymphocytes). Maraviroc (a CCR5 antagonist) blocks this step. Before initiating maraviroc, viral tropism testing is required.

Goodman & Gilman's Pharmacological Basis of Therapeutics; Lippincott's Pharmacology, 7e

Q4. Reverse transcriptase of HIV lacks which key activity, making the HIV genome highly prone to mutations?

A) Polymerase activity B) RNase H activity C) Proofreading (3' to 5' exonuclease) activity D) Integrase activity

Answer: C - Proofreading (3' to 5' exonuclease) activity

Reverse transcriptase lacks the error-checking (proofreading) capability of normal DNA polymerases. This results in an extremely high mutation rate for the HIV genome (~1 error per replication cycle), driving rapid viral evolution and drug resistance. This is why multi-drug ART is required to "keep ahead" of the high mutation rate.

Basic Medical Biochemistry, 6e (Lippincott)

Q5. A healthcare worker sustains a needle stick injury from an HIV-positive patient's blood. What is the approximate risk of HIV transmission from a single hollow-bore needle stick?

A) 1 in 10 (10%) B) 1 in 300 (0.3%) C) 1 in 100 (1%) D) 1 in 10,000 (0.01%)

Answer: B - 1 in 300 (0.3%)

The seroconversion rate after a single hollow-bore needle stick from a contaminated needle is approximately 0.3% (1 in 300). Mucous membrane exposure carries a lower risk of about 0.09%. Post-exposure prophylaxis (PEP) with antiretroviral drugs significantly reduces this risk and should be initiated within 72 hours.

Ananthanarayan's Textbook of Microbiology, 6e, p. 551

Q6. Which of the following regarding the "window period" in HIV infection is CORRECT?

A) The window period refers to the period when p24 antigen is detectable but antibodies are absent B) HIV seroconversion usually occurs within 4 weeks; the window period can last up to 3 months C) HIV RNA cannot be detected during the window period D) Fourth-generation assays do NOT help shorten the window period

Answer: B - HIV seroconversion usually occurs ~4 weeks after initial infection; the window period can last up to 3 months

The "window period" is the time between HIV infection and the appearance of detectable antibodies. Fourth-generation (4th Gen) combination assays detect BOTH anti-HIV IgM/IgG antibodies AND the p24 capsid antigen simultaneously, shortening the window period significantly. HIV RNA tests can turn positive 10-15 days after exposure, even earlier than p24 detection.

Dermatology 2-Volume Set 5e; Robbins & Kumar Basic Pathology

Q7. After a reactive HIV ELISA (screening test), the standard confirmatory test used traditionally has been:

A) CD4 count B) HIV viral load (RNA PCR) C) Western blot D) p24 antigen detection

Answer: C - Western blot

Western blot has historically been the gold-standard confirmatory test after a reactive ELISA. It detects antibodies to specific HIV proteins (gp120, gp41, p24, p31, etc.). Currently, fourth-generation combo assays and HIV-1/HIV-2 differentiation immunoassays are preferred per updated CDC guidelines, but Western blot remains the classic answer in NEET PG PYQs.

Medical Microbiology 9e (Murray et al.)

Q8. The HIV-1 genome contains two regulatory genes (tat and rev) and FOUR accessory genes. Which of the following correctly lists all four accessory genes?

A) gag, pol, env, tat B) vif, vpr, vpu, nef C) tat, rev, nef, vif D) tax, rex, vpr, vpu

Answer: B - vif, vpr, vpu, nef

HIV-1 has the standard retroviral structural genes (gag, pol, env) PLUS:

2 regulatory genes: tat (transactivator of transcription) and rev (regulates splicing/export of viral RNA)
4 accessory genes: vif, vpr, vpu, and nef

HTLV (by contrast) has tax and rex as regulatory genes. This distinction is a classic NEET PG question.

Sherris & Ryan's Medical Microbiology, 8e; Medical Microbiology 9e

Q9. Macrophages serve as an important reservoir for HIV. Which statement about HIV and its host cell interactions is FALSE?

A) Macrophages act as a long-term reservoir for HIV B) Lysis of infected CD4 T cells occurs during HIV replication C) Follicular dendritic cells (FDCs) can be infected with HIV even without CD4 involvement D) Macrophages do NOT support HIV replication

Answer: D - Macrophages do NOT support HIV replication (this is FALSE - macrophages DO support HIV replication)

Macrophages are an important reservoir - they support HIV replication and are not destroyed as rapidly as CD4 T cells. Follicular dendritic cells from tonsils can harbor HIV even without CD4 involvement. CD4 T cell lysis is the primary mechanism of immunodeficiency in AIDS.

Ananthanarayan's Textbook of Microbiology, 6e, p. 546

Q10. Which route of HIV transmission carries the HIGHEST probability of infection per exposure?

A) Single episode of unprotected vaginal intercourse B) Sharing needles among IV drug users C) Blood/blood product transfusion D) Transplacental (mother to baby)

Answer: C - Blood/blood product transfusion (>90%)

The risk per exposure by route:

Blood/blood product transfusion: >90% (highest)
Organ/tissue donation: 5-90%
Mother to baby (vertical): ~30%
Sharing needles (IV drug use): 0.5-1%
Sexual intercourse (oral/vaginal/anal): 0.1-1%
Ananthanarayan's Textbook of Microbiology, 6e, p. 551

Quick Summary Table

Q#	Topic	Key Fact
1	Classification	Retroviridae, Lentivirus; diploid (+) RNA
2	Structure	gp160 cleaved → gp120 + gp41
3	Entry	CD4 + CCR5 / CXCR4 co-receptors
4	Reverse transcriptase	No proofreading → high mutation rate
5	Needle stick risk	0.3% (1 in 300)
6	Window period	~4 weeks; up to 3 months; 4th-gen assays shorten it
7	Confirmatory test	Western blot (classic); now HIV-1/2 differentiation assay
8	Accessory genes	vif, vpr, vpu, nef (tat and rev are regulatory, not accessory)
9	Reservoir	Macrophages and FDCs are reservoirs; FDCs don't need CD4
10	Transmission risk	Blood transfusion >90% (highest per exposure)

Give me 10 hsv 1 and hsv 2 microbiology mcq based on pyqs of neet pg

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HSV 1 HSV 2 herpes simplex NEET PG microbiology previous year questions MCQ

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