Virology — MCQs

A transplant patient with serologic evidence of previous Epstein-Barr virus infection was on high levels of immunosuppressive medications. The patient presents with generalized lymphadenopathy, fever, night sweats, weight loss, abdominal pain, and tonsillitis. The dosage of immunosuppressive drugs was decreased, leading to regression of the lymphadenopathy. Which of the following is the most likely diagnosis for this patient?

Q307Easy

All of the following are true about cytomegalovirus except:

Q308Easy

KFD (Kyasanur Forest Disease) is caused by which type of virus?

Q309Easy

Cholera toxin binds to which receptors in the intestine?

Q310Easy

Which of the following viruses does NOT cause pneumonia?

Virology Indian Medical PG Practice Questions and MCQs

Question 301: All of the following are prion diseases except?

A. Kuru (KJD)
B. Subacute spongiform encephalopathies
C. Mink encephalopathy
D. Burkitt lymphoma (Correct Answer)

Explanation: ### Explanation The correct answer is **Burkitt lymphoma** because it is a malignancy of B-lymphocytes caused by the **Epstein-Barr Virus (EBV)**, not a prion. Prions are unique infectious agents composed entirely of protein (PrPSc), lacking any nucleic acid (DNA or RNA). **Analysis of Options:** * **Burkitt lymphoma (Option D):** This is a high-grade B-cell neoplasm associated with the c-myc translocation [t(8;14)]. It is etiologically linked to EBV, a DNA virus, making it the "except" in this list. * **Kuru (Option A):** A classic human prion disease historically found in the Fore people of Papua New Guinea, transmitted through ritualistic cannibalism. * **Subacute Spongiform Encephalopathies (Option B):** This is the umbrella term for all prion diseases (including Creutzfeldt-Jakob Disease). They are characterized by long incubation periods, neuronal loss, and a "spongiform" (vacuolated) appearance of the brain parenchyma without inflammatory response. * **Mink Encephalopathy (Option C):** This is a veterinary prion disease (Transmissible Mink Encephalopathy) similar to Scrapie in sheep or Bovine Spongiform Encephalopathy (Mad Cow Disease) in cattle. **NEET-PG High-Yield Pearls:** 1. **Prion Characteristics:** Resistant to standard sterilization (autoclaving at 121°C). They require **134°C for 1-2 hours** or immersion in **1N NaOH**. 2. **Diagnosis:** Confirmed by brain biopsy showing amyloid plaques. The **14-3-3 protein** in CSF is a specific marker for CJD. 3. **Human Prion Diseases:** Kuru, CJD, Variant CJD (linked to Mad Cow), Gerstmann-Sträussler-Scheinker (GSS) syndrome, and Fatal Familial Insomnia (FFI).

Question 302: An infant develops a cough and fever. The X-ray examination is suggestive of bronchopneumonia. Which of the following viruses is NOT a common causative agent of bronchopneumonia in infants?

A. Parainfluenza viruses
B. Influenza virus A
C. Respiratory syncytial virus
D. Mumps virus (Correct Answer)

Explanation: **Explanation:** The correct answer is **D. Mumps virus**. **Why Mumps virus is the correct answer:** Mumps virus is a member of the *Rubulavirus* genus within the Paramyxoviridae family. Its primary clinical manifestation is **nonsuppurative parotitis** (painful swelling of the salivary glands). While it is a respiratory virus transmitted via droplets, it characteristically disseminates hematogenously to glandular tissues (testes, ovaries, pancreas) and the central nervous system (meningitis). It is **not** a primary respiratory pathogen and does not cause bronchopneumonia in infants. **Why the other options are incorrect:** * **Respiratory Syncytial Virus (RSV):** This is the **most common** cause of bronchiolitis and pneumonia in infants and children under 1 year of age. It typically presents with wheezing and respiratory distress. * **Parainfluenza viruses:** Specifically Types 1, 2, and 3 are major causes of lower respiratory tract infections in infants. While Type 1 is the leading cause of Croup (Laryngotracheobronchitis), Type 3 is a frequent cause of pneumonia and bronchiolitis. * **Influenza virus A:** This virus can cause severe primary viral pneumonia or predispose patients to secondary bacterial bronchopneumonia. It is a significant cause of respiratory morbidity in the pediatric population. **Clinical Pearls for NEET-PG:** * **Most common cause of Bronchiolitis:** RSV. * **Most common cause of Croup (Laryngotracheobronchitis):** Parainfluenza Type 1 (look for "steeple sign" on X-ray). * **Mumps Complications:** Orchitis (most common in post-pubertal males, can lead to atrophy but rarely sterility) and Oophoritis. * **Mumps Diagnosis:** Elevated serum amylase (due to parotid involvement) is a high-yield laboratory finding.

Question 303: Ebola virus belongs to which of the following viral families?

A. Reovirus
B. Filovirus (Correct Answer)
C. Herpes virus
D. Rotavirus

Explanation: **Explanation:** **Correct Answer: B. Filovirus** The Ebola virus belongs to the **Filoviridae** family. The name "Filo" is derived from the Latin *filum*, meaning thread-like, which describes the characteristic long, filamentous, and pleomorphic morphology of these viruses under electron microscopy. They are enveloped, single-stranded, negative-sense RNA viruses. Ebola, along with Marburg virus, causes severe **Viral Hemorrhagic Fever (VHF)** characterized by high fever, coagulopathy, and multi-organ failure. **Analysis of Incorrect Options:** * **A. Reovirus:** This family consists of non-enveloped, double-stranded RNA viruses with a segmented genome. A key member is the Colorado tick fever virus. * **C. Herpes virus:** These are large, enveloped, double-stranded DNA viruses. Common members include HSV-1, HSV-2, VZV, and CMV. They are known for establishing latency in host cells. * **D. Rotavirus:** While Rotavirus is a member of the Reoviridae family, it is listed separately here. It is the most common cause of severe dehydrating diarrhea in infants and children worldwide. **High-Yield Clinical Pearls for NEET-PG:** * **Transmission:** Ebola is transmitted through direct contact with infected blood, secretions, or bodily fluids (e.g., sweat, semen). * **Natural Reservoir:** Fruit bats (Pteropodidae family) are considered the natural hosts. * **Diagnosis:** Real-time PCR is the preferred diagnostic test during the acute phase; ELISA is used for detecting IgM/IgG antibodies later. * **Morphology:** Look for "Shepherd’s crook" or "6-shaped" appearance on electron microscopy. * **Biosafety Level:** Ebola virus requires **BSL-4** containment (the highest level).

Question 304: Which of the following are classified as myxoviruses?

A. Measles virus
B. Parainfluenza virus
C. Influenza virus
D. All of the above (Correct Answer)

Explanation: **Explanation:** The term **Myxoviruses** (from the Greek *myxo*, meaning mucus) refers to a group of RNA viruses that have a specific affinity for mucins (glycoproteins) on the surface of red blood cells and host respiratory cells. Historically, this group is divided into two major families: **Orthomyxoviridae** and **Paramyxoviridae**. 1. **Influenza virus (Option C):** This is the classic representative of the **Orthomyxoviridae** family. It possesses the enzyme neuraminidase, which allows it to interact with and break down mucopolysaccharides on cell surfaces. 2. **Measles and Parainfluenza viruses (Options A & B):** These belong to the **Paramyxoviridae** family. While they are larger and more pleomorphic than Orthomyxoviruses, they share the property of adhering to mucous membranes and, in many cases, causing hemagglutination. **Why "All of the above" is correct:** In the context of medical microbiology exams, "Myxoviruses" is used as an umbrella term encompassing both families. Since Measles, Parainfluenza, and Influenza all fall under this classification based on their structural and biological affinity for mucins, all options are correct. **High-Yield NEET-PG Pearls:** * **Genome Difference:** Orthomyxoviruses (Influenza) have a **segmented** RNA genome (8 segments in Influenza A and B), allowing for **antigenic shift**. Paramyxoviruses have a **non-segmented** genome. * **Replication Site:** Most RNA viruses replicate in the cytoplasm, but **Influenza** is a notable exception as it replicates in the **nucleus**. * **Diagnostic Feature:** Paramyxoviruses (like Measles) often induce the formation of **multinucleated giant cells (syncytia)** via their Fusion (F) protein.

Question 305: What is the causative agent of Kaposi's sarcoma?

A. Hepatitis B virus (HBV)
B. Hepatitis C virus (HCV)
C. Human herpesvirus (HHV) (Correct Answer)
D. Herpes simplex virus (HSV)

Explanation: **Explanation:** The correct answer is **Human herpesvirus (HHV)**, specifically **HHV-8**, also known as **Kaposi’s Sarcoma-associated Herpesvirus (KSHV)**. **1. Why the Correct Answer is Right:** HHV-8 is a gamma-herpesvirus that infects vascular endothelial cells. It carries oncogenes (like viral cyclin D and v-GPCR) that dysregulate the cell cycle and promote angiogenesis. This leads to the characteristic proliferation of spindle cells and "slit-like" vascular spaces seen in Kaposi’s sarcoma (KS). KS is a defining opportunistic neoplasm in HIV/AIDS patients but also occurs in endemic (African) and classic (Mediterranean) forms. **2. Why the Incorrect Options are Wrong:** * **Hepatitis B (HBV) & Hepatitis C (HCV):** These are hepatotropic viruses. While they are oncogenic, they are primarily associated with **Hepatocellular Carcinoma (HCC)**, not vascular tumors. * **Herpes Simplex Virus (HSV):** HSV-1 and HSV-2 (Alpha-herpesviruses) cause vesicular lesions (cold sores and genital herpes) and latent infections in sensory ganglia, but they do not possess oncogenic potential. **3. High-Yield Clinical Pearls for NEET-PG:** * **Transmission:** HHV-8 is primarily transmitted through saliva and sexual contact. * **Histology:** Look for **spindle-shaped cells**, extravasated RBCs, and hemosiderin-laden macrophages. * **Associated Malignancies:** Besides KS, HHV-8 is also the causative agent of **Primary Effusion Lymphoma (PEL)** and **Multicentric Castleman Disease**. * **Treatment:** Highly Active Antiretroviral Therapy (HAART) is the first-line management in HIV-positive patients to restore immune function.

Question 306: A transplant patient with serologic evidence of previous Epstein-Barr virus infection was on high levels of immunosuppressive medications. The patient presents with generalized lymphadenopathy, fever, night sweats, weight loss, abdominal pain, and tonsillitis. The dosage of immunosuppressive drugs was decreased, leading to regression of the lymphadenopathy. Which of the following is the most likely diagnosis for this patient?

A. Burkitt lymphoma
B. Hodgkin lymphoma
C. Infectious mononucleosis
D. Post-transplant lymphoproliferative disorder (Correct Answer)

Explanation: ### Explanation **1. Why the Correct Answer is Right (Post-transplant lymphoproliferative disorder - PTLD):** PTLD is a spectrum of B-cell proliferations ranging from benign hyperplasia to malignant lymphoma, occurring in the setting of chronic immunosuppression (post-organ or bone marrow transplant). * **Pathogenesis:** In healthy individuals, EBV-infected B-cells are kept in check by **cytotoxic T-cells (CD8+)**. In transplant patients, high-dose immunosuppression impairs T-cell surveillance, allowing EBV-driven B-cell proliferation. * **Clinical Clue:** The hallmark of early/polymorphic PTLD is that it often **regresses upon reduction or withdrawal of immunosuppressive therapy**, as this allows the patient’s own T-cells to recover and attack the EBV-infected cells. This specific detail in the vignette is pathognomonic for PTLD. **2. Why Incorrect Options are Wrong:** * **Burkitt Lymphoma:** While EBV-associated (especially the endemic form), it is a high-grade malignancy characterized by the *c-myc* translocation (t[8;14]). It does not regress simply by reducing immunosuppression. * **Hodgkin Lymphoma:** EBV is associated with the Mixed Cellularity subtype. However, Hodgkin lymphoma presents with Reed-Sternberg cells and requires chemotherapy; it is not managed by adjusting immunosuppressants. * **Infectious Mononucleosis:** This is a primary EBV infection. This patient already had "serologic evidence of previous infection," making a primary acute infection unlikely. Furthermore, the context of transplant and systemic symptoms strongly points toward PTLD. **3. NEET-PG High-Yield Pearls:** * **EBV Association:** EBV is linked to Burkitt Lymphoma, Nasopharyngeal Carcinoma, Oral Hairy Leukoplakia (in HIV), and PTLD. * **Receptor:** EBV enters B-cells via the **CD21** receptor (also the receptor for C3d complement). * **Diagnosis:** PTLD is confirmed by biopsy showing lymphoid proliferation and EBV-encoded RNA (EBER) in-situ hybridization. * **Management:** The first-line step in PTLD management is the **reduction of immunosuppression (RIS)**. If RIS fails, Rituximab (anti-CD20) is used.

Question 307: All of the following are true about cytomegalovirus except:

A. May be transmitted from pregnant mother to fetus
B. Is Human herpesvirus 5
C. Causes lymphocyte enlargement (Correct Answer)
D. Causes congenital diseases

Explanation: **Explanation:** The correct answer is **C (Causes lymphocyte enlargement)**. While Cytomegalovirus (CMV) is a member of the Herpesviridae family, the hallmark of its pathology is **cytomegaly (enlargement of the cell)**, characterized by large cells with prominent intranuclear inclusions ("Owl's eye" appearance). It does not specifically cause the enlargement of lymphocytes; rather, it typically induces a **lymphocytosis** with **atypical lymphocytes** (Downey cells), which are activated T-cells responding to the infection. **Evaluation of other options:** * **Option A & D:** CMV is the most common cause of **congenital viral infections**. It can be transmitted transplacentally (vertical transmission) from mother to fetus, leading to "Cytomegalic Inclusion Disease." Clinical features include microcephaly, periventricular calcifications, hepatosplenomegaly, and sensorineural hearing loss. * **Option B:** CMV is officially classified as **Human Herpesvirus 5 (HHV-5)**, belonging to the Beta-herpesvirinae subfamily. **High-Yield Clinical Pearls for NEET-PG:** * **Morphology:** Large cells with "Owl’s eye" intranuclear inclusions. * **Transmission:** Saliva, urine, blood, semen, breast milk, and organ transplants. * **Clinical Presentation:** In immunocompetent hosts, it causes a Mononucleosis-like syndrome (Heterophile antibody/Monospot test **negative**). In HIV patients (CD4 <50), it causes retinitis, esophagitis, and colitis. * **Treatment:** Ganciclovir is the drug of choice; Foscarnet is used for resistant cases.

Question 308: KFD (Kyasanur Forest Disease) is caused by which type of virus?

A. Flavivirus (Correct Answer)
B. Myxovirus
C. Alphavirus
D. Phlebovirus

Explanation: **Explanation:** **Kyasanur Forest Disease (KFD)**, popularly known as "Monkey Fever," is caused by the Kyasanur Forest Disease Virus (KFDV). 1. **Why Flavivirus is Correct:** KFDV belongs to the family **Flaviviridae** and the genus *Flavivirus*. It is a tick-borne viral hemorrhagic fever endemic to the Western Ghats of India (specifically Karnataka). It is transmitted to humans via the bite of infected ticks (*Haemaphysalis spinigera*) or through contact with infected monkeys (Langurs and Bonnet macaques), which act as amplifiers. 2. **Why Other Options are Incorrect:** * **Myxovirus:** This group includes Orthomyxoviruses (e.g., Influenza) and Paramyxoviruses (e.g., Measles, Mumps). These are primarily respiratory viruses, not tick-borne hemorrhagic agents. * **Alphavirus:** Part of the *Togaviridae* family, these include viruses like Chikungunya and Sindbis. While they are arboviruses, they typically cause fever and arthralgia rather than the specific hemorrhagic manifestations of KFD. * **Phlebovirus:** A genus within the *Phenuiviridae* family (formerly Bunyaviridae), which includes Rift Valley Fever and Sandfly fever. While some are tick-borne, KFD specifically belongs to the Flavivirus genus. **High-Yield Clinical Pearls for NEET-PG:** * **Vector:** *Haemaphysalis spinigera* (Hard tick). * **Reservoir/Amplifier:** Monkeys (Sudden deaths in local monkey populations are a sentinel sign of an outbreak). * **Clinical Presentation:** Biphastic illness—initial high fever, headache, and severe myalgia, followed by a second phase of neurological symptoms or hemorrhagic manifestations in some patients. * **Diagnosis:** PCR (early phase) or IgM ELISA. * **Prevention:** A formalin-inactivated KFDV vaccine is used in endemic areas of India.

Question 309: Cholera toxin binds to which receptors in the intestine?

A. Sphingosine through the A subunit
B. Sphingosine through the B subunit
C. GM1 gangliosides through the A subunit
D. GM1 gangliosides through the B subunit (Correct Answer)

Explanation: **Explanation:** The pathogenesis of *Vibrio cholerae* is primarily mediated by the **Cholera Toxin (Choleragen)**, which is a classic **A-B type enterotoxin**. 1. **Why Option D is correct:** The toxin consists of two main components: one **A (Active) subunit** and five **B (Binding) subunits**. The **B subunits** act as the "key" that recognizes and binds specifically to the **GM1 ganglioside receptors** located on the surface of enterocytes in the small intestine. Once bound, the A subunit is internalized to activate adenylate cyclase, leading to increased cAMP and the characteristic "rice-water" diarrhea. 2. **Why other options are incorrect:** * **Options A & B:** Sphingosine is a component of cell membranes (and a precursor to gangliosides), but it is not the specific receptor for the cholera toxin. * **Option C:** While the A subunit is the enzymatically active part that causes the disease (by ADP-ribosylation of Gs protein), it **cannot bind** to the cell on its own. The B subunit is exclusively responsible for attachment. **NEET-PG High-Yield Pearls:** * **Mechanism:** Increased **cAMP** $\rightarrow$ Inhibition of NaCl absorption and stimulation of $Cl^-$ secretion $\rightarrow$ Osmotic loss of water. * **Receptor:** **GM1 Ganglioside** (Mnemonic: **G**o **M**ore **1**—as in more diarrhea). * **Stool Characteristics:** "Rice-water" stool, non-inflammatory (no RBCs or WBCs), high in potassium and bicarbonate. * **Other toxins using GM1:** The Heat-Labile (LT) toxin of *E. coli* is structurally and functionally similar to the cholera toxin.

Question 310: Which of the following viruses does NOT cause pneumonia?

A. Cytomegalovirus
B. Mumps virus (Correct Answer)
C. Measles virus
D. Retrovirus

Explanation: **Explanation:** The correct answer is **Mumps virus**. While many respiratory and systemic viruses can lead to pulmonary involvement, Mumps virus is characteristically associated with glandular and neurological involvement rather than pneumonia. **Why Mumps virus is the correct answer:** Mumps is primarily a systemic viral infection caused by a Rubulavirus (Paramyxoviridae). Its hallmark clinical presentation involves **nonsuppurative parotitis** (salivary gland swelling). Common complications include orchitis (most common in post-pubertal males), oophoritis, pancreatitis, and aseptic meningitis. It does not typically involve the lower respiratory tract or cause pneumonia. **Why the other options are incorrect:** * **Cytomegalovirus (CMV):** A major cause of viral pneumonia, particularly in **immunocompromised patients** (e.g., post-transplant recipients or HIV patients). Histology typically shows "Owl’s eye" intranuclear inclusions. * **Measles virus:** A member of the Paramyxoviridae family that frequently causes respiratory complications. It can cause primary viral pneumonia (**Hecht’s giant cell pneumonia**) or lead to secondary bacterial pneumonia. * **Retrovirus (HIV):** While HIV itself doesn't cause pneumonia directly, it leads to profound immunosuppression, making patients highly susceptible to opportunistic pulmonary infections (e.g., *Pneumocystis jirovecii*, CMV, and fungal pneumonias). Additionally, HTLV-1 (another retrovirus) is associated with chronic lung diseases. **High-Yield Clinical Pearls for NEET-PG:** * **Measles:** Look for Koplik spots and Warthin-Finkeldey giant cells. * **CMV:** Most common viral cause of pneumonia in bone marrow transplant recipients. * **Mumps:** Most common cause of bilateral parotitis; most common cause of viral orchitis. * **RSV:** The most common cause of bronchiolitis and pneumonia in infants.

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?