Virology MCQs

Question 1

Which of the following statements is true about the pathogenesis of HSV-2?

Accepted Answer

Most persons who are seropositive for HSV-2 but report no symptoms still shed virus from the genital area intermittently — Most HSV-2 seropositive individuals are asymptomatic but still shed virus intermittently from the genital mucosa — making them unknowing transmitters. This asymptomatic shedding is the primary driver of HSV-2 spread. HSV-2 is actually associated with increased HIV acquisition risk, making C false.

Question 2

Which clinical presentation is typical of a primary first episode HSV-2 infection?

Accepted Answer

Lesions present, symptoms usually severe, HSV-1 and HSV-2 antibodies are not present — A true primary first episode HSV-2 infection means no prior HSV exposure of any type. Therefore both HSV-1 and HSV-2 antibodies are absent, and the clinical presentation is typically severe — extensive lesions, systemic symptoms (fever, malaise, lymphadenopathy), and prolonged viral shedding.

Question 3

Viruses that contain two complete copies of positive strand RNA and the enzyme reverse transcriptase are:

Accepted Answer

Retroviruses — Retroviruses (e.g., HIV) carry two identical copies of positive-sense single-stranded RNA and the enzyme reverse transcriptase, which converts viral RNA into DNA for integration into the host genome. This diploid RNA genome is unique to retroviruses among animal viruses.

Question 4

Bacteriophages that can enter into stable, long-term relationships with their hosts are called:

Accepted Answer

Temperate phages — Temperate phages integrate their genome into the bacterial chromosome as a prophage, establishing a stable long-term lysogenic relationship with the host. They replicate silently with the bacterium until triggered to enter the lytic cycle. Examples include bacteriophage lambda (λ).

Question 5

The positive strand of certain viruses does not act as a messenger but becomes converted into DNA and integrated into the host cellular DNA. These viruses are:

Accepted Answer

Retroviruses — This describes the retrovirus replication cycle. Their positive-strand RNA genome is converted to double-stranded DNA by reverse transcriptase, then integrated into the host genome by integrase as a provirus. This is distinct from other positive-strand RNA viruses that use their genome directly as mRNA.

Question 6

Infants infected with cytomegaloviruses (CMV) in utero may suffer from:

Accepted Answer

Any of these — Congenital CMV is the most common intrauterine infection. It can cause a wide spectrum of damage including mental retardation, sensorineural hearing loss, hepatosplenomegaly (enlarged spleen and liver), microcephaly, and chorioretinitis. Severely affected infants may present with "blueberry muffin" rash due to extramedullary hematopoiesis.

Question 7

Viroids are unusual in that they:

Accepted Answer

Have no capsid protein or envelope — Viroids are the smallest known infectious agents — they consist of a short, circular, single-stranded RNA molecule with no protein coat (capsid) and no envelope whatsoever. They are even smaller than viruses and cause disease primarily in plants (e.g., potato spindle tuber disease).

Question 8

Creutzfeldt-Jakob disease (CJD), Kuru, scrapie, and Mad Cow disease are caused by:

Accepted Answer

Prions — Prions are misfolded proteins (PrP^Sc) that cause fatal neurodegenerative spongiform encephalopathies. They contain no nucleic acid — making them unique among all known infectious agents. They are extraordinarily resistant to heat, radiation, and standard disinfection. CJD, Kuru, scrapie (sheep), and variant CJD (Mad Cow) are all prion diseases.

Question 9

The human virus that has been associated with Burkitt's lymphoma (a malignant tumor of the jaw) is:

Accepted Answer

Epstein-Barr virus — EBV is strongly associated with Burkitt's lymphoma — a B-cell malignancy classically presenting as a jaw tumor in African children. EBV immortalizes B lymphocytes. It is also associated with infectious mononucleosis, nasopharyngeal carcinoma, and Hodgkin's lymphoma.

Question 10

What causes Encephalitis or Acute Encephalitis Syndrome (AES)?

Accepted Answer

Both A and B — Acute Encephalitis Syndrome (AES) is defined as inflammation of the brain parenchyma, most commonly caused by viral infections (HSV, JE virus, enteroviruses, arboviruses). Both statements are correct — AES is viral-mediated inflammatory brain disease.

Question 11

What are the symptoms of Encephalitis or Acute Encephalitis Syndrome?

Accepted Answer

All the above — AES presents with the classic triad of fever, altered consciousness/confusion, and neurological deficits. Additional symptoms include vomiting, seizures, headache, photophobia, and focal neurological signs depending on the brain region affected.

Question 12

Treatments given to encephalitis or AES patients are:

Accepted Answer

All the above — Management of AES is supportive and includes corticosteroids (to reduce cerebral edema), mechanical ventilation (if respiratory compromise), and anticonvulsants (to control seizures). Acyclovir is added if HSV encephalitis is suspected. ICU-level care is often required.

Question 13

Genital herpes are caused by the herpes simplex viruses:

Accepted Answer

HSV-1 and HSV-2 — Genital herpes is caused by both HSV-1 and HSV-2. Historically HSV-2 was the dominant cause, but HSV-1 now accounts for a significant and growing proportion of genital herpes cases, especially in young adults, likely due to orogenital transmission.

Question 14

Which of the following statements is true about the transmission of HSV?

Accepted Answer

HSV is readily inactivated by drying and soap and water — HSV is an enveloped virus and is therefore relatively fragile outside the host. It is rapidly inactivated by desiccation (drying), soap, and water — explaining why fomite transmission is rare. Most transmission actually occurs during asymptomatic shedding (making D false).

Question 15

HSV systemic antiviral chemotherapy includes which of the following oral medications?

Accepted Answer

All of the above — All three are nucleoside analogue antivirals active against HSV. Acyclovir is the prototype; Valacyclovir is the oral prodrug of acyclovir with better bioavailability; Famciclovir is the prodrug of penciclovir. All three are used for genital herpes treatment and suppression.

Question 16

The patient becomes very upset after learning that she has HSV infection and inquires about future risks, especially transmission risks if she has other sexual partners without HSV. Which is the most appropriate answer?

Accepted Answer

She is always at risk for shedding the virus — Once infected with HSV, the virus establishes lifelong latency in sensory ganglia. Viral shedding — both symptomatic and asymptomatic — occurs intermittently for life. There is no cure, and she will always carry transmission risk. Suppressive antiviral therapy (acyclovir/valacyclovir) can reduce but not eliminate shedding.

Question 17

What is the only DNA virus that causes hepatitis?

Accepted Answer

Hepatitis B virus — Hepatitis B virus (HBV) is the only DNA virus among the major hepatitis viruses. It belongs to the Hepadnaviridae family with a partially double-stranded circular DNA genome. HAV is a picornavirus (ssRNA), HCV is a flavivirus (ssRNA), and HDV is a virusoid (negative-sense ssRNA).

Question 18

Poliovirus has an affinity for what body system?

Accepted Answer

Nervous system — Poliovirus enters via the fecal-oral route and replicates in the gut, but its primary tropism is the anterior horn motor neurons of the spinal cord. Destruction of these neurons causes the flaccid paralysis characteristic of paralytic poliomyelitis. The virus uses CD155 (PVR) as its receptor on neural cells.

Question 19

How is hepatitis A transmitted?

Accepted Answer

Fecal-oral route — HAV is transmitted exclusively by the fecal-oral route — contaminated water, raw shellfish, unwashed produce, and poor hand hygiene. It is a non-enveloped virus, making it resistant to environmental conditions. Unlike HBV/HCV, it is NOT sexually transmitted or bloodborne as a primary route.

Question 20

Which of the following specimens contain/s hepatitis B virus in an infected person?

Accepted Answer

All of these — HBV is found in blood, semen, vaginal secretions, saliva, breast milk, and other body fluids. Blood has the highest viral concentration. This explains its transmission routes — sexual contact, needlesharing, vertical (mother to child), and rarely saliva (deep kissing, bites).

Question 21

The diagnosis of hepatitis A virus infection is carried out from the method based on:

Accepted Answer

Detection of IgM anti-HAV by ELISA — The gold standard for acute HAV diagnosis is detection of IgM anti-HAV antibodies by ELISA — these appear at onset of symptoms and persist for 3-6 months. Elevated aminotransferases indicate liver injury but are nonspecific. Fecal HAV detection is possible but not the standard diagnostic method.

Question 22

Which statement regarding the herpesvirus family is incorrect?

Accepted Answer

They replicated in the host cell cytoplasm — Herpesviruses are DNA viruses that replicate in the nucleus, NOT the cytoplasm. DNA replication, transcription, and capsid assembly all occur in the nucleus. The virus then acquires its envelope by budding through the nuclear membrane. This distinguishes them from poxviruses, which are the only DNA viruses that replicate in the cytoplasm.

Virology MCQs

Questions, Answers & Explanations