All Free Microbiology MCQs with Answers

• A. Adeno
• B. Hepatitis
• C. EB virus
• D. Parvo virus

Explanation: Parvovirus B19 infects erythroid precursor cells and can temporarily stop red-cell production, causing an aplastic crisis in patients with…

• A. CD8 T-cells
• B. CD4 T-cells
• C. B - cells
• D. NK - cells

Explanation: HIV gp120 attaches first to the CD4 receptor on helper T lymphocytes, followed by interaction with a chemokine coreceptor such as CCR5 or…

• A. HBc Ag
• B. HBs Ag
• C. Hbe Ag
• D. HBx Ag

Explanation: HBxAg refers to the hepatitis B virus X protein, a small nonstructural regulatory protein that transactivates viral and cellular genes and…

• A. Hepatitis A
• B. Hepatitis B
• C. CMV
• D. EBV

Explanation: Cytomegalovirus is a frequent and important opportunistic infection after organ transplantation because immunosuppressive therapy weakens…

• A. Nasopharyngeal carcinoma
• B. Burkitt's lymphoma
• C. Hepatoma
• D. Infectious mononucleosis

Explanation: EBV is associated with infectious mononucleosis, Burkitt lymphoma and nasopharyngeal carcinoma.

• A. Carcinoma
• B. Kaposi's sarcoma
• C. Melanoma
• D. Ewing's sarcoma

Explanation: Kaposi sarcoma, caused by human herpesvirus 8, is a classic AIDS-associated tumour because severe immunosuppression permits HHV-8-driven…

• A. Picorna viruses
• B. Herpes viruses
• C. Hepadana viruses
• D. Flavi viruses

Explanation: Hepatitis C virus is an enveloped, positive-sense RNA virus in the family Flaviviridae.

• A. Tissue culture
• B. Embryonated eggs
• C. Animals
• D. Chemically defined media

Explanation: Viruses require living cells for replication, so they can be grown in tissue culture, embryonated eggs, or experimental animals.

• A. ELISA IS - ve
• B. Western Blot is - ve
• C. Both are - ve
• D. PCR is - ve

Explanation: During the HIV window period, antibodies have not yet reached detectable levels, so both ELISA and Western blot are usually negative.

• A. Capsomere
• B. Capsid
• C. Nucleocapsid
• D. Envelope

Explanation: The capsid is the protein coat surrounding viral nucleic acid. Capsomeres are its individual protein subunits, while a nucleocapsid…

• A. DNA virus
• B. Attacks CD4 cells
• C. Macrophages are the reservoir
• D. Decrease CD4 count in late stages

Explanation: HIV is an RNA retrovirus, not a DNA virus, although it forms a DNA provirus inside host cells.

• A. Carcinoma of nasopharynx
• B. Papilloma
• C. Infectious mononucleosis
• D. Burkitt's lymphoma

Explanation: EBV is associated with infectious mononucleosis, Burkitt lymphoma, and nasopharyngeal carcinoma.

• A. HB Ag
• B. HBs AG
• C. HBV
• D. None of the above

Explanation: The Australian antigen is hepatitis B surface antigen, abbreviated HBsAg.

• A. Virus isolation
• B. Western blot followed by ELISA
• C. ELISA followed by western blot technique
• D. Polymers chain reaction

Explanation: The conventional HIV testing sequence uses ELISA as the screening test, followed by Western blot confirmation of reactive results.

• A. Hepatitis C
• B. Hepatitis D
• C. Hepatitis E
• D. Hepatitis F

Explanation: Hepatitis E is the enterically transmitted non-A, non-B hepatitis virus, usually spread through contaminated food or water.

• A. Antibody of HBs Ag is associated with resistance to infection
• B. Antibody to HBC is not protective
• C. Highest titres of anti HBC are found in persistent carriers of HBs Ag
• D. CMI disappears soon after recover

Explanation: Anti-HBs antibodies are associated with immunity and resistance to HBV infection, whether produced after recovery or vaccination.

• A. Cytopathic changes in culture cells
• B. Presence of viral protein in the infected monolayer
• C. Haemagglutination test
• D. Haemagglutination inhibition test

Explanation: Cytopathic effects, such as cell rounding, fusion, or detachment, are the classic way to detect virus growth in cultured cells.

• A. HBV
• B. IgG anti HAV
• C. Delta Virus
• D. HBC Ag

Explanation: The Dane particle is the complete, infectious hepatitis B virion, consisting of the core and envelope.

• A. Failure to thrive
• B. Have infections
• C. 50% chances to have AIDS
• D. All are true

Explanation: Infants born to mothers with HIV may develop failure to thrive and recurrent infections, but the risk of vertical transmission is…

• A. 24 Hrs
• B. 3-4 days
• C. 2 weeks
• D. 10 daysInfectious Diseases

Explanation: Koplik spots usually appear about 2 to 3 days before the measles rash, commonly described in exam texts as 3 to 4 days.