Virology 2

Question 1

What are the targets for herpes simplex viruses?

Accepted Answer

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.

Question 2

Which statement regarding the poxviruses is incorrect?

Accepted Answer

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.

Question 3

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

Accepted Answer

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.

Question 4

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

Accepted Answer

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.

Question 5

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

Accepted Answer

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.

Question 6

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

Accepted Answer

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.

Question 7

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

Accepted Answer

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.

Question 8

Which virus is most strongly associated with cervical cancer?

Accepted Answer

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.

Question 9

What are haemagglutinin and neuraminidase?

Accepted Answer

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.

Question 10

What increases the possibility of antigenic shift in influenza virus?

Accepted Answer

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.

Question 11

What virus commonly undergoes both antigenic shifts and antigenic drifts?

Accepted Answer

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.

Question 12

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

Accepted Answer

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.

Question 13

How are all the important human paramyxoviruses transmitted?

Accepted Answer

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.

Question 14

What types of nucleocapsid do arboviruses possess?

Accepted Answer

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.

Question 15

Which is NOT a chief vector of the arboviruses?

Accepted Answer

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.

Question 16

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

Accepted Answer

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.

Question 17

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

Accepted Answer

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.

Question 18

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

Accepted Answer

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.

Question 19

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

Accepted Answer

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.

Question 20

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

Accepted Answer

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.

Question 21

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:

Accepted Answer

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).

Question 22

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

Accepted Answer

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.

Question 23

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?

Accepted Answer

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.

Question 24

In which age group does COVID-19 spread?

Accepted Answer

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.

Question 25

Mild symptoms of Novel coronavirus are:

Accepted Answer

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.

Question 26

Which of the following diseases are related to coronavirus?

Accepted Answer

All A, B and C — Coronaviruses cause MERS (MERS-CoV), SARS (SARS-CoV-1), and COVID-19 (SARS-CoV-2). All three are betacoronaviruses causing severe pneumonia originating from animal reservoirs.

Question 27

Name a clinical trial in which blood is transfused from recovered COVID-19 patients to a coronavirus patient who is in critical condition?

Accepted Answer

Plasma Therapy — Convalescent plasma therapy involves transfusing plasma containing anti-SARS-CoV-2 antibodies from recovered patients to critically ill patients. The Solidarity trial tested multiple treatments including remdesivir.

Question 28

Regarding viral infection of the central nervous system (CNS), one of the statements below is false:

Accepted Answer

HSV encephalitis is a post-infectious encephalomyelitis — HSV encephalitis is a DIRECT viral encephalitis — the virus actively replicates within brain parenchyma. It is NOT post-infectious. Measles encephalitis (ADEM) IS a post-infectious autoimmune encephalomyelitis.

Question 29

One of the best ways to diagnose meningitis or encephalitis is through:

Accepted Answer

A spinal tap — Lumbar puncture (spinal tap) with cerebrospinal fluid (CSF) analysis is the gold standard for diagnosing meningitis and encephalitis. CSF findings help differentiate causes and PCR of CSF is definitive for viral agents.

Question 30

Resistance to a viral infection is LEAST LIKELY to depend on which of the following:

Accepted Answer

Size of the viral genome — The size of the viral genome has no bearing on host resistance to infection. Resistance depends on immunocompetence, prior vaccination/immunity, and age. Gender can also play a role.

Question 31

All of the following are examples of superficial mycoses EXCEPT:

Accepted Answer

White piedra — White piedra is a superficial mycosis, but it is caused by Trichosporon species and affects the hair shaft, typically producing white or cream-colored nodules. The other options are also superficial mycoses affecting the skin or hair.

Question 32

Which statement regarding aspergillosis is correct?

Accepted Answer

The clinical manifestations of aspergillosis include local infections of the ear, cornea, nails, and sinuses — Aspergillus causes a spectrum of disease ranging from superficial (otomycosis, onychomycosis, keratitis) to invasive (sinusitis, pulmonary, disseminated). ABPA is associated with eosinophilia, corticosteroids increase risk, and sputum cultures are often colonizers.

Question 33

Which statement regarding sporotrichosis is correct?

Accepted Answer

The etiologic agent is a dimorphic fungus — Sporothrix schenckii is a classic thermally dimorphic fungus. Its ecology is well-known (soil, decaying vegetation, rose thorns), most cases show the lymphocutaneous pattern, and most patients are immunocompetent.

Question 34

Which statement about blastomycosis is correct?

Accepted Answer

In tissue, one finds large, thick-walled, single budding yeast cells with broad connections between the parent yeast and bud — The pathognomonic tissue finding of blastomycosis is large, thick-walled yeast cells with a single broad-based bud. Blastomycosis primarily affects males, starts in the lungs, and is endemic to North America.

Question 35

Blastomyces dermatitidis is a dimorphic fungus. All of the following are characteristics of the yeast form EXCEPT:

Accepted Answer

The incubation temperature is 25-degree Celsius — The yeast form of B. dermatitidis grows at 37°C (body temperature). At 25°C it grows as the mold form. This is the fundamental rule of thermal dimorphism.

Question 36

In recent years, opportunistic mycoses in immunocompromised individuals are caused by various fungi including molds. All of the following are examples of yeasts and molds EXCEPT:

Accepted Answer

Histoplasma capsulatum — Histoplasma capsulatum is a primary pathogen, not typically classified as an opportunistic mold causing disease in immunocompromised individuals in the same category as the others. All the others are true opportunistic fungi.

Question 37

Fungi exist in which form?

Accepted Answer

All of above — Fungi exist as yeasts (unicellular), moulds/molds (multicellular filamentous), and mushrooms (macroscopic fruiting bodies). Dimorphic fungi exist as both yeast and mold depending on temperature.

Question 38

Phospholipases are enzymes that do which of the following?

Accepted Answer

Degrade cell membranes to allow pathogens to escape phagosomes — Phospholipases hydrolyze phospholipids in cell membranes, enabling the pathogen to escape phagolysosomes, invade deeper tissues, and evade killing by macrophages. They are key to invasive infections.

Question 39

Which of the following pathogens undergoes antigenic variation to avoid immune defenses?

Accepted Answer

Plasmodium — Plasmodium (malaria parasite) undergoes extensive antigenic variation of its surface proteins to evade host immunity. While Candida undergoes phenotypic switching, classical antigenic variation is the hallmark of Plasmodium.

Question 40

Which of the following is NOT a characteristic of fungi?

Accepted Answer

None of the above — All listed options are valid fungal characteristics. Fungi are eukaryotes, reproduce by both sexual and asexual spores, and pathogenic species exhibit thermodimorphism (mold at 25°C, yeast at 37°C).

Question 41

Asexual methods in fungi consist of all of the following EXCEPT:

Accepted Answer

Spermatization — Spermatization is a sexual reproductive process involving the transfer of spermatia to receptive hyphae. Asexual methods include fragmentation, budding, fission, and spore formation.

Question 42

Which of the following is a sexual spore?

Accepted Answer

Ascospore — Ascospores are sexual spores produced inside an ascus (sac) following meiosis in Ascomycota. Zoospores, aplanospores, and sporangiospores are all asexual spores.

Virology 2

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