Virology — MCQs

Virology Indian Medical PG Practice Questions and MCQs

Question 511: All of the following are included in Jones minor criteria except?

A. Fever
B. Raised ESR and CRP
C. Arthralgia
D. Erythema marginatum (Correct Answer)

Explanation: The **Jones Criteria** are used for the clinical diagnosis of **Acute Rheumatic Fever (ARF)**, a non-suppurative complication of Group A Streptococcus infection. The criteria are divided into Major and Minor categories. ### **Explanation of the Correct Answer** **D. Erythema marginatum** is a **Major Criterion**, not a minor one. It is a characteristic, evanescent, non-pruritic pink rash with serpiginous borders, typically found on the trunk and limbs. Because it is highly specific for ARF, it is categorized as a major manifestation alongside Carditis, Polyarthritis, Chorea, and Subcutaneous nodules. ### **Explanation of Incorrect Options** The following are all **Minor Criteria** (representing non-specific signs of inflammation): * **A. Fever:** A common systemic sign of inflammation in ARF. * **B. Raised ESR and CRP:** These are acute-phase reactants indicating systemic inflammation. * **C. Arthralgia:** Joint pain without objective findings (like swelling or redness). Note: If polyarthritis is present, arthralgia cannot be counted as a minor criterion. ### **High-Yield Clinical Pearls for NEET-PG** * **Diagnosis Requirement:** 2 Major OR 1 Major + 2 Minor criteria, **PLUS** evidence of preceding Streptococcal infection (e.g., elevated ASO titer, positive throat culture, or Rapid Antigen Detection Test). * **Mnemonic for Major Criteria (J♥NES):** * **J** - Joints (Migratory Polyarthritis) * **♥** - Carditis (Pancarditis) * **N** - Nodules (Subcutaneous) * **E** - Erythema marginatum * **S** - Sydenham’s Chorea * **ECG Finding:** Prolonged **PR interval** is a Minor Criterion (unless carditis is already a major criterion). * **Revised Jones Criteria (2015):** Now differentiates between Low-risk and Moderate/High-risk populations (where monoarthritis/monoarthralgia may be considered).

Question 512: What causes SARS?

A. Influenza virus
B. Coronavirus (Correct Answer)
C. Bacillus anthracis
D. Poxvirus

Explanation: **Explanation:** **SARS (Severe Acute Respiratory Syndrome)** is caused by the **SARS-associated coronavirus (SARS-CoV)**. Coronaviruses are large, enveloped, positive-sense single-stranded RNA viruses characterized by club-shaped surface projections (peplomers) that create a "halo" or crown-like appearance under electron microscopy. SARS-CoV emerged in 2002-2003, originating in bats and spreading to humans via intermediate hosts like civet cats. It primarily infects the lower respiratory tract by binding to **ACE2 receptors**. **Analysis of Incorrect Options:** * **A. Influenza virus:** Causes the seasonal flu and pandemics (e.g., H1N1). While it causes respiratory distress, it belongs to the *Orthomyxoviridae* family and is genetically distinct from coronaviruses. * **C. Bacillus anthracis:** This is a Gram-positive, spore-forming bacterium that causes Anthrax. While "Inhalation Anthrax" causes severe respiratory failure (Woolsorter’s disease), it is not a viral syndrome. * **D. Poxvirus:** These are the largest DNA viruses (e.g., Variola virus causing Smallpox). They typically present with vesicular skin rashes rather than primary viral pneumonia. **High-Yield Clinical Pearls for NEET-PG:** * **Receptor:** SARS-CoV and SARS-CoV-2 both utilize the **ACE2 (Angiotensin-Converting Enzyme 2)** receptor for cell entry. * **Morphology:** Coronaviruses have the **largest genome** among RNA viruses. * **Diagnosis:** Gold standard is **RT-PCR** from respiratory samples. * **Radiology:** Characterized by "Ground Glass Opacities" (GGO) on HRCT chest. * **Related Viruses:** MERS-CoV (Middle East Respiratory Syndrome) uses the **DPP-4 receptor** and is linked to camels.

Question 513: A patient has the following laboratory results for Hepatitis B virus infection: HBsAg Negative, AntiHBsAg Negative, IgM antiHBC Positive, IgG anti HBC Negative. What do these test results indicate?

A. Chronic infection
B. Immunization
C. Window period (Correct Answer)
D. Previous infection

Explanation: ### Explanation The laboratory profile provided indicates the **Window Period** of a Hepatitis B virus (HBV) infection. **1. Why "Window Period" is correct:** The window period is the clinical interval during which **HBsAg** (the first marker to appear) has disappeared from the blood, but **Anti-HBs** (the neutralizing antibody) has not yet reached detectable levels. During this "gap," the only reliable marker of an acute infection is **IgM anti-HBc** (antibody against the core antigen). * **HBsAg (-):** Surface antigen is cleared. * **Anti-HBs (-):** Protective antibodies haven't appeared yet. * **IgM anti-HBc (+):** Confirms a recent/acute infection. **2. Why other options are incorrect:** * **Chronic Infection:** Would be characterized by the persistence of **HBsAg** for >6 months and the presence of **IgG anti-HBc**, not IgM. * **Immunization (Vaccination):** Only **Anti-HBs** would be positive. Since the vaccine contains only the surface protein, core antibodies (Anti-HBc) will always be negative. * **Previous Infection (Recovery):** Both **Anti-HBs** and **IgG anti-HBc** would be positive, indicating the patient has cleared the virus and developed immunity. **3. NEET-PG High-Yield Pearls:** * **IgM anti-HBc** is the **sole marker** of infection during the window period. * **HBsAg** is the first marker to appear (at 4–6 weeks) and indicates infectivity. * **Anti-HBs** signifies immunity (via recovery or vaccination). * **HBeAg** is a marker of active viral replication and high infectivity. * **Anti-HBc** (Total) is the best marker to screen for previous exposure, as it remains positive for life.

Question 514: Which of the following is associated with a haemopoietic malignancy?

A. HTLV-1 (Correct Answer)
B. EBV
C. Parvovirus B19
D. HHV-8

Explanation: **Explanation:** The correct answer is **HTLV-1 (Human T-cell Lymphotropic Virus type 1)**. **1. Why HTLV-1 is correct:** HTLV-1 is a retrovirus that specifically infects CD4+ T-lymphocytes. It is the definitive causative agent of **Adult T-cell Leukemia/Lymphoma (ATLL)**, a highly aggressive peripheral T-cell neoplasm. The virus utilizes the **Tax protein**, which activates host cell genes involved in proliferation (like IL-2 and its receptor) and inhibits tumor suppressor genes (like p53), leading to malignant transformation of hematopoietic cells. **2. Why the other options are incorrect:** * **EBV (Epstein-Barr Virus):** While EBV is strongly associated with lymphomas (Burkitt’s, Hodgkin’s) and nasopharyngeal carcinoma, it is primarily linked to **lymphoid** malignancies rather than being the "classic" answer for a direct hematopoietic malignancy in this specific MCQ context. HTLV-1 is the more specific association for a T-cell malignancy. * **Parvovirus B19:** This virus targets erythrocyte precursors in the bone marrow but causes **aplastic crisis** or erythema infectiosum, not malignancy. * **HHV-8 (Kaposi Sarcoma-associated Herpesvirus):** This is associated with **Kaposi Sarcoma** (an endothelial tumor) and Primary Effusion Lymphoma, but it is not the primary answer for general hematopoietic malignancy compared to HTLV-1. **High-Yield Clinical Pearls for NEET-PG:** * **ATLL Presentation:** Look for "flower cells" (clover-leaf nuclei) on peripheral smear, hypercalcemia, and lytic bone lesions. * **HTLV-1 Transmission:** Similar to HIV (breast milk, sexual contact, blood transfusion). * **Other HTLV-1 Condition:** Tropical Spastic Paraparesis (a demyelinating disease). * **Tax & HBZ genes:** Key oncogenic drivers in HTLV-1 pathogenesis.

Question 515: Influenza is caused by which type of virus?

A. Orthomyxovirus, a DNA virus
B. Paramyxovirus, an RNA virus
C. Paramyxovirus, a DNA virus
D. Orthomyxovirus, an RNA virus (Correct Answer)

Explanation: **Explanation:** The Influenza virus belongs to the **Orthomyxoviridae** family. It is characterized as a **single-stranded, negative-sense, segmented RNA virus**. The segmentation of its genome (8 segments in Influenza A and B) is a critical feature, as it allows for **genetic reassortment**, leading to "Antigenic Shift"—the mechanism behind major global pandemics. **Analysis of Options:** * **Option D (Correct):** Influenza is an Orthomyxovirus and contains an RNA genome. * **Option A:** Incorrect because Orthomyxoviruses are RNA viruses, not DNA viruses. Almost all significant respiratory viruses (except Adenovirus) are RNA-based. * **Option B:** Incorrect. While Paramyxoviruses are RNA viruses, they represent a different family including Mumps, Measles, and RSV. They have a non-segmented genome and do not undergo antigenic shift. * **Option C:** Incorrect. Paramyxoviruses are RNA viruses, not DNA. **High-Yield Clinical Pearls for NEET-PG:** 1. **Antigenic Drift vs. Shift:** *Drift* involves point mutations (causes seasonal epidemics); *Shift* involves genetic reassortment of segments (causes pandemics). 2. **Surface Glycoproteins:** Hemagglutinin (HA) is for cell entry/attachment; Neuraminidase (NA) is for progeny release. 3. **Site of Replication:** Uniquely among RNA viruses (except Retroviruses), Influenza replicates its genome in the **host cell nucleus**. 4. **Drug of Choice:** Oseltamivir (Tamiflu) acts by inhibiting Neuraminidase. 5. **Strains:** Influenza A causes both pandemics and epidemics; Influenza B causes only epidemics; Influenza C causes mild respiratory illness.

Question 516: Which anti-rabies vaccine has been recommended by WHO?

A. Ducek cell vaccine
B. Chick fibroblast vaccine
C. HDCV (Correct Answer)
D. Sheep brain vaccine

Explanation: **Explanation:** The World Health Organization (WHO) recommends the use of **Modern Cell Culture Vaccines (CCVs)** and **Embryonated Egg-based Vaccines (EEVs)** for both pre-exposure and post-exposure prophylaxis. Among these, the **Human Diploid Cell Vaccine (HDCV)** is considered the "gold standard" due to its high immunogenicity and superior safety profile. **Analysis of Options:** * **HDCV (Correct):** Developed using the Pitman-Moore strain of the rabies virus grown in human diploid cells (MRC-5). It is highly effective and has the lowest rate of adverse neurological reactions. * **Ducek cell vaccine (Incorrect):** This is a distractor; there is no recognized rabies vaccine by this name. * **Chick fibroblast vaccine (Incorrect):** While Purified Chick Embryo Cell Vaccine (PCECV) is a WHO-recommended CCV, "Chick fibroblast vaccine" is an imprecise term. HDCV remains the primary reference vaccine. * **Sheep brain vaccine (Incorrect):** Also known as the **Semple vaccine**, this is a Nerve Tissue Vaccine (NTV). WHO has strictly advocated for the discontinuation of NTVs because they are less immunogenic and carry a high risk of severe neuroparalytic complications (e.g., Acute Disseminated Encephalomyelitis) due to the presence of myelin. **High-Yield Clinical Pearls for NEET-PG:** * **Current WHO Schedule (Intramuscular):** The Essen regimen (0, 3, 7, 14, and 28 days). * **Current WHO Schedule (Intradermal):** The updated Thai Red Cross regimen (2-2-2-0-2) is widely used in India for cost-effectiveness. * **Site of Injection:** Always the **deltoid muscle** in adults or the anterolateral thigh in children. **Never** in the gluteal region (lower neutralizing antibody titers). * **Category III Bites:** Require both vaccine and Rabies Immunoglobulin (RIG) infiltrated around the wound.

Question 517: Swine flu is due to which influenza virus subtype?

A. H1N1 (Correct Answer)
B. H5N1
C. H2N2
D. H3N2

Explanation: **Explanation:** **Influenza A virus** is classified into subtypes based on two surface glycoproteins: **Hemagglutinin (H)** and **Neuraminidase (N)**. 1. **Why H1N1 is correct:** The **H1N1** subtype is the causative agent of **Swine Flu**. While H1N1 has circulated in humans for decades, a novel triple-reassortant strain emerged in 2009 (Pandemic 2009), originating from pigs, leading to a global pandemic. It is characterized by rapid person-to-person transmission via respiratory droplets. 2. **Analysis of Incorrect Options:** * **H5N1:** This is the highly pathogenic **Avian Influenza (Bird Flu)**. It primarily affects birds; human infection is rare but carries a high mortality rate (>50%). * **H2N2:** This subtype caused the **"Asian Flu" pandemic of 1957**. It is no longer in active circulation among humans. * **H3N2:** This is a subtype of seasonal influenza that caused the **"Hong Kong Flu" pandemic of 1968**. It remains a major cause of annual seasonal flu outbreaks alongside H1N1. **High-Yield Clinical Pearls for NEET-PG:** * **Antigenic Shift:** Major genetic changes (reassortment) leading to **Pandemics** (e.g., 2009 H1N1). * **Antigenic Drift:** Minor point mutations leading to **Epidemics** and the need for annual vaccine updates. * **Drug of Choice:** **Oseltamivir** (Neuraminidase inhibitor), effective against both Influenza A and B. * **Diagnosis:** **RT-PCR** of nasopharyngeal swabs is the gold standard. * **Spanish Flu (1918):** Also caused by an H1N1 subtype; it remains the deadliest pandemic in history.

Question 518: Which of the following inclusion bodies is seen in a patient with Rabies?

A. Cowdry-B
B. Negri bodies (Correct Answer)
C. Guarneri bodies
D. Bollinger bodies

Explanation: **Explanation:** **Negri bodies** are the hallmark histopathological finding in **Rabies**, caused by the Lyssavirus. These are pathognomonic **intracytoplasmic, eosinophilic inclusion bodies** found most commonly in the **Purkinje cells of the cerebellum** and the **pyramidal cells of the hippocampus (Ammon’s horn)**. They represent sites of viral replication and consist of ribonucleoprotein aggregates. **Analysis of Incorrect Options:** * **Cowdry-B:** These are intranuclear inclusions seen in **Poliovirus** and Adenovirus infections. (Note: Cowdry-A inclusions are seen in Herpes Simplex Virus and Varicella-Zoster Virus). * **Guarneri bodies:** These are eosinophilic intracytoplasmic inclusions characteristic of **Variola (Smallpox)** and Vaccinia viruses. * **Bollinger bodies:** These are large, granular intracytoplasmic inclusions seen in **Fowlpox**. (Note: Borrel bodies are the smaller elementary bodies found within Bollinger bodies). **High-Yield Clinical Pearls for NEET-PG:** * **Morphology:** Negri bodies are typically round or oval, 1–7 µm in size, and contain internal granules (inner bodies). * **Diagnosis:** While Negri bodies are specific, they are only present in about 70–80% of cases. The **Direct Fluorescent Antibody (DFA)** test on brain tissue or skin biopsy (from the nape of the neck) is the current "gold standard" for diagnosis. * **Transmission:** Rabies is most commonly transmitted via the bite of a rabid animal (dogs in India); the virus travels via **retrograde axonal transport** to the CNS.

Question 519: Antigenic variation is seen in all EXCEPT:

A. Influenza type A
B. Influenza type B
C. Influenza type C (Correct Answer)
D. None of the above

Explanation: **Explanation:** The core concept behind this question is the mechanism of genetic diversity in Orthomyxoviruses. **Antigenic variation** (shifts and drifts) is the primary method these viruses use to evade the host immune system. **Why Influenza Type C is the correct answer:** Influenza Type C is characterized by its **genomic stability**. Unlike types A and B, it lacks the high frequency of mutations required for significant antigenic variation. It typically causes only mild respiratory illness and does not cause epidemics or pandemics. Furthermore, Influenza C possesses only **one surface glycoprotein** (Hemagglutinin-esterase fusion protein), whereas A and B have two (Hemagglutinin and Neuraminidase), providing fewer targets for variation. **Analysis of Incorrect Options:** * **A. Influenza Type A:** This type exhibits the most dramatic antigenic variation. It undergoes both **Antigenic Drift** (point mutations) and **Antigenic Shift** (genetic reassortment). Shift occurs because Type A infects multiple species (birds, pigs, humans), leading to pandemics. * **B. Influenza Type B:** This type undergoes **Antigenic Drift** only. Because it lacks a significant animal reservoir, genetic reassortment (Shift) does not occur. However, the drift is frequent enough to require regular updates to the seasonal flu vaccine. **High-Yield Clinical Pearls for NEET-PG:** * **Antigenic Shift:** Sudden, major change; results in a new subtype (e.g., H1N1 to H2N2); responsible for **Pandemics**. Seen only in Type A. * **Antigenic Drift:** Gradual, minor change; results in new strains; responsible for **Epidemics**. Seen in both Type A and B. * **Genome:** Influenza viruses have a **segmented, negative-sense RNA genome**. Type A and B have 8 segments; Type C has 7 segments. * **Amantadine/Rimantadine:** Effective only against Influenza A (targets M2 protein, which Type B lacks).

Question 520: Homologous serum jaundice is a disease caused by which hepatitis virus?

A. Hepatitis Virus A
B. Hepatitis Virus B (Correct Answer)
C. Hepatitis Virus C
D. None of these

Explanation: **Explanation:** **Hepatitis B Virus (HBV)** is historically and clinically referred to as **Homologous Serum Jaundice**. This term was coined because the disease is primarily transmitted through the parenteral route—specifically via the transfusion of homologous blood or serum, contaminated needles, or clinical procedures. Unlike Hepatitis A, which is characterized by short incubation periods and fecal-oral spread, HBV has a long incubation period (6 weeks to 6 months) and is a DNA virus (Hepadnaviridae). **Analysis of Options:** * **Hepatitis Virus A (Option A):** Known as **Infectious Hepatitis**. It is transmitted via the fecal-oral route, typically through contaminated food or water, and has a short incubation period. * **Hepatitis Virus C (Option B):** Previously known as the major cause of **Post-Transfusion Hepatitis (PTH)** or "Non-A, Non-B Hepatitis." While also blood-borne, the specific historical term "Homologous Serum Jaundice" is reserved for HBV. * **Hepatitis Virus E:** Known as **Enterically Transmitted Non-A, Non-B Hepatitis**, similar to HAV in its transmission. **High-Yield Clinical Pearls for NEET-PG:** * **Genome:** HBV is the only **DNA Hepatitis virus** (partially double-stranded circular DNA); all others (A, C, D, E) are RNA viruses. * **Dane Particle:** The complete infectious virion of HBV. * **Serological Markers:** * **HBsAg:** First marker to appear; indicates active infection. * **Anti-HBs:** Indicates immunity (post-vaccination or recovery). * **HBeAg:** Marker of high infectivity and active viral replication. * **Ground Glass Hepatocytes:** The characteristic histopathological finding in chronic HBV infection due to HBsAg accumulation in the endoplasmic reticulum.

Practice by Chapter

Virus Structure and Classification

Practice Questions

Viral Replication

Practice Questions

Pathogenesis of Viral Infections

Practice Questions

DNA Viruses: Herpesviruses

Practice Questions

DNA Viruses: Poxviruses and Adenoviruses

Practice Questions

Hepatitis Viruses

Practice Questions

RNA Viruses: Orthomyxoviruses

Practice Questions

RNA Viruses: Paramyxoviruses

Practice Questions

Enteroviruses and Rhinoviruses

Practice Questions

Arboviruses

Practice Questions

HIV and Retroviruses

Practice Questions

Oncogenic Viruses

Practice Questions

Want unlimited practice?

Get full access to all questions, explanations, and performance tracking.

Start For Free

Virology — MCQs

Virology — MCQs

On this page

Practice by Chapter

Want unlimited practice?