Virology 2 – 42 MCQs | Kenya MBChB

42 Year 3: Medical Virology exam questions on Virology 2 for medical students. Includes MCQs, answers, explanations and written questions. Sample: What are the

This MCQ set contains 42 questions on Virology 2 in the Year 3: Medical Virology unit. Each question includes the correct answer and a detailed explanation for active recall and exam preparation.

Q1: What are the targets for herpes simplex viruses?

  1. A. Neurons
  2. B. Epidermis
  3. C. Hepatocytes
  4. D. Mucous membranes

Correct answer: D – Mucous membranes

HSV primarily infects and replicates in mucous membranes and skin epithelium at the site of entry, then establishes latency in sensory neurons. The primary productive infection target is mucosal epithelium, not neurons directly.

Q2: Which statement regarding the poxviruses is incorrect?

  1. A. They are the largest and most complex of all the animal viruses
  2. B. They have the largest genome of all viruses
  3. C. They multiply in the cytoplasm
  4. D. They are non-enveloped DNA viruses

Correct answer: D – They are non-enveloped DNA viruses

Poxviruses are enveloped and have a complex lipid envelope. They are unique as the only DNA viruses that replicate entirely in the cytoplasm, forming Guarnieri inclusion bodies. They are the largest and most complex animal viruses with the largest genome.

Q3: What is the portal of entry for varicella-zoster virus?

  1. A. Respiratory epithelium
  2. B. Mouth
  3. C. Conjunctiva
  4. D. Through a break in the skin

Correct answer: A – Respiratory epithelium

VZV (chickenpox/shingles virus) enters via inhalation of infectious respiratory droplets or aerosols, infecting the respiratory epithelium first. It then disseminates via viremia to produce the characteristic widespread vesicular rash.

Q4: When are people infected with varicella-zoster virus most contagious?

  1. A. 1-2 days prior to the development of the rash
  2. B. When the rash appears
  3. C. When the skin lesions become itchy
  4. D. When the lesions become encrusted

Correct answer: A – 1-2 days prior to the development of the rash

VZV is most contagious during the prodromal phase, 1-2 days before the rash appears, when the patient feels unwell but has no visible lesions. Infectivity continues until all lesions are crusted over.

Q5: What group tends to develop a more virulent form of cytomegalovirus infection?

  1. A. Women of childbearing age
  2. B. Young adults
  3. C. IV drug abusers
  4. D. Newborns

Correct answer: D – Newborns

Congenital CMV in newborns causes the most severe disease, including mental retardation, sensorineural hearing loss, chorioretinitis, hepatosplenomegaly, and microcephaly. Newborns lack mature immune systems and cannot control primary CMV infection.

Q6: Both Burkitt's lymphoma and infectious mononucleosis are caused by what virus?

  1. A. Cytomegalovirus
  2. B. Epstein-Barr virus
  3. C. Varicella-zoster virus
  4. D. Herpes simplex-1

Correct answer: B – Epstein-Barr virus

EBV causes both infectious mononucleosis (kissing disease) and Burkitt's lymphoma (malignant B-cell tumor). Both involve B-lymphocyte tropism. EBV also causes nasopharyngeal carcinoma and Hodgkin's lymphoma.

Q7: Where is the niche for Epstein-Barr virus in humans?

  1. A. Respiratory epithelium
  2. B. Thoracic nerves
  3. C. Liver
  4. D. Lymphoid tissue and salivary glands

Correct answer: D – Lymphoid tissue and salivary glands

EBV establishes latency in B lymphocytes (lymphoid tissue) and reactivates in salivary gland epithelium, explaining why it is shed in saliva and transmitted via kissing. This dual tropism is central to its biology.

Q8: Which virus is most strongly associated with cervical cancer?

  1. A. Epstein-Barr virus
  2. B. Human T-cell lymphotropic virus
  3. C. Human immunodeficiency virus
  4. D. Human papilloma virus

Correct answer: D – Human papilloma virus

HPV, particularly high-risk types 16 and 18, is the causative agent of virtually all cervical cancers. HPV oncoproteins E6 and E7 inactivate tumor suppressors p53 and Rb respectively, driving malignant transformation.

Q9: What are haemagglutinin and neuraminidase?

  1. A. Exotoxins produced by the influenza virus
  2. B. Glycoprotein receptors on influenza's target cells
  3. C. Glycoproteins on influenza virus that contribute to virulence
  4. D. Proteins found in the nucleus of influenza virus

Correct answer: C – Glycoproteins on influenza virus that contribute to virulence

Haemagglutinin (HA) and Neuraminidase (NA) are surface glycoproteins on the influenza virion. HA mediates attachment to sialic acid receptors on host cells. NA cleaves sialic acid to release new virions. Both are key virulence factors.

Q10: What increases the possibility of antigenic shift in influenza virus?

  1. A. The presence of neutralizing antibodies to influenza
  2. B. The presence of herd immunity
  3. C. The annual flu shot
  4. D. The simultaneous infection of one individual with two different strains of influenza

Correct answer: D – The simultaneous infection of one individual with two different strains of influenza

Antigenic shift occurs when two different influenza A strains infect the same host cell simultaneously, allowing their segmented genomes to reassort, producing a new hybrid virus with a novel HA or NA combination.

Q11: What virus commonly undergoes both antigenic shifts and antigenic drifts?

  1. A. HIV
  2. B. Ebola
  3. C. Rotavirus
  4. D. Influenza

Correct answer: D – Influenza

Influenza A undergoes both antigenic drift (gradual point mutations) and antigenic shift (sudden reassortment producing pandemic strains), making it uniquely difficult to control with long-term vaccines.

Q12: Which member of the paramyxovirus family can cause very serious croup?

  1. A. Measles
  2. B. Respiratory syncytial virus (RSV)
  3. C. Hendra
  4. D. Meta pneumo virus

Correct answer: B – Respiratory syncytial virus (RSV)

RSV is the leading cause of severe croup (laryngotracheobronchitis) and bronchiolitis in infants and young children, causing subglottic swelling that produces the classic barking seal cough and inspiratory stridor.

Q13: How are all the important human paramyxoviruses transmitted?

  1. A. By direct contact with infected rodents
  2. B. By respiratory droplets
  3. C. By the bite of an infected arthropod
  4. D. By sexual transmission

Correct answer: B – By respiratory droplets

All major human paramyxoviruses (measles, mumps, RSV, parainfluenza, metapneumovirus) are transmitted by respiratory droplets and direct contact with infected secretions, explaining their high contagiousness.

Q14: What types of nucleocapsid do arboviruses possess?

  1. A. Icosahedral; +ssRNA
  2. B. Complex; dsDNA
  3. C. Icosahedral; -ssRNA
  4. D. Complex; dsRNA

Correct answer: A – Icosahedral; +ssRNA

Most arboviruses (arthropod-borne viruses) belong to families like Flaviviridae and Togaviridae, which possess icosahedral nucleocapsids and positive-sense single-stranded RNA genomes.

Q15: Which is NOT a chief vector of the arboviruses?

  1. A. Gnats
  2. B. Mosquitoes
  3. C. Spiders
  4. D. Flies

Correct answer: C – Spiders

Spiders are arachnids but are not vectors of arboviruses. The principal arthropod vectors are mosquitoes, ticks, gnats/midges, and sandflies/flies. Spiders do not feed on blood and do not transmit viruses.

Q16: What mode of HIV transmission is growing more rapidly than any other?

  1. A. Sexual transmission between homosexual or bisexual males
  2. B. Blood transfusions and blood products
  3. C. Sharing of contaminated needles
  4. D. Congenital or neonatal AIDS

Correct answer: C – Sharing of contaminated needles

Intravenous drug use with shared needles represents the most rapidly growing mode of HIV transmission globally. Blood transfusions are now well-screened, and heterosexual transmission has overtaken homosexual transmission globally in absolute numbers.

Q17: Why is poliovirus able to survive the gastric environment and other harsh conditions?

  1. A. It has a naked capsid
  2. B. It has a phospholipids envelope
  3. C. Its capsid is composed of flagellin protein
  4. D. It is a dsDNA virus

Correct answer: A – It has a naked capsid

Poliovirus is a non-enveloped (naked) virus, making it highly resistant to gastric acid, bile salts, detergents, and desiccation. This protects the viral RNA through the harsh GI environment, enabling fecal-oral transmission.

Q18: Which is NOT a class of drugs used in HIV/AIDS therapy?

  1. A. Synthetic nucleotides
  2. B. Reverse transcriptase inhibitors
  3. C. Ribozyme inhibitors
  4. D. Protease inhibitors

Correct answer: C – Ribozyme inhibitors

Ribozyme inhibitors are NOT an established class of HIV drugs. The recognized classes of antiretrovirals include NRTIs, NNRTIs, protease inhibitors, integrase inhibitors, fusion inhibitors, and CCR5 antagonists.

Q19: Which method would one use to identify virus-infected host cells?

  1. A. Immunofluorescence test
  2. B. Haemagglutination test
  3. C. Immunoblotting test
  4. D. All of the above

Correct answer: D – All of the above

Immunofluorescence uses fluorescent antibodies to detect viral antigens. Haemagglutination detects viruses that agglutinate red blood cells. Immunoblotting detects viral proteins. All can identify virus-infected cells.

Q20: Many antiviral drugs act by inhibition of a viral DNA polymerase enzyme. Select the virus for which this class of drugs would be effective.

  1. A. Cytomegalovirus
  2. B. Influenza
  3. C. Measles
  4. D. Mumps

Correct answer: A – Cytomegalovirus

CMV is a DNA virus that uses its own DNA polymerase for replication, making it a valid target for DNA polymerase inhibitors like ganciclovir. Influenza, measles, and mumps are RNA viruses.

Q21: A male baby is born at 39 weeks gestation with a petechial rash, low birth weight, hepatosplenomegaly, and bilateral cataracts. This is thought to be due to an infection acquired while in utero. Select the most likely condition:

  1. A. Cytomegalovirus
  2. B. Group B streptococcus
  3. C. Rubella virus
  4. D. Toxoplasma gondii

Correct answer: C – Rubella virus

The combination of bilateral cataracts, petechial rash, hepatosplenomegaly, and low birth weight in a neonate is the classic presentation of Congenital Rubella Syndrome (CRS).

Q22: All the following viruses are transmitted by respiratory routes EXCEPT ONE:

  1. A. Human papilloma virus
  2. B. Rhinovirus
  3. C. Adenovirus
  4. D. Measles virus

Correct answer: A – Human papilloma virus

HPV is NOT transmitted by respiratory droplets; its primary routes are direct skin-to-skin contact and sexual contact. Rhinovirus, adenovirus, and measles virus are primarily spread via the respiratory route.

Q23: When a person sneezes or coughs, droplets spread in the air or fall on nearby surfaces. If another person inhales droplets or touches contaminated surfaces then touches their face, and if the distance is less than 1 meter from the infected person, how does SARS-CoV-2 spread?

  1. A. The distance is less than 1 meter from the infected person
  2. B. If another person inhales droplets or touches contaminated surfaces then touches their face
  3. C. When a person sneezes or coughs, droplets spread in the air or fall on nearby surfaces
  4. D. All the above are correct

Correct answer: D – All the above are correct

SARS-CoV-2 spreads through respiratory droplets, aerosols, and fomites. All three mechanisms described are correct. Proximity of less than 1 meter significantly increases transmission risk.

Q24: In which age group does COVID-19 spread?

  1. A. COVID-19 occurs in all age groups
  2. B. Coronavirus infection is mild in children
  3. C. Older persons and those with pre-existing conditions are at high risk
  4. D. All the above are correct

Correct answer: D – All the above are correct

COVID-19 infects all age groups, but disease severity is age-dependent. Children typically have milder disease, while the elderly and those with comorbidities face disproportionately high risk of severe disease and death.

Q25: Mild symptoms of Novel coronavirus are:

  1. A. All the above
  2. B. Cough
  3. C. Shortness of breath
  4. D. Fever

Correct answer: A – All the above

The WHO-recognized mild symptoms of COVID-19 include fever, dry cough, and shortness of breath, along with fatigue, loss of smell/taste, sore throat, and myalgia. Progression to pneumonia and ARDS characterizes severe disease.

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