Virology Practice Questions

Q: Which of the following viruses does NOT belong to Group B arboviruses?

Chikungunya virus. **Explanation:** The classification of arboviruses was historically based on antigenic relationships (serology). **Group B arboviruses** correspond to the modern family ***Flaviviridae*** (specifically the genus *Flavivirus*), while **Group A arboviruses** correspond to the family ***Togaviridae*** (specifically the genus *Alphavirus*). **1. Why Chikungunya is the correct answer:** Chikungunya virus belongs to the **Alphavirus** genus (Group A). It is an enveloped, positive-sense single-stranded RNA virus. Clinically, it is characterized by high fever and severe, often lingering, polyarthralgia, transmitted primarily by *Aedes aegypti* and *Aedes albopictus*. **2. Why the other options are incorrect:** * **Dengue virus (Option A):** A classic member of the *Flavivirus* genus (Group B). It has four serotypes (DEN 1-4) and is the most common arboviral disease worldwide. * **Japanese Encephalitis virus (Option B):** A member of the *Flavivirus* genus (Group B). It is the leading cause of viral encephalitis in Asia, transmitted by *Culex* mosquitoes. * **West Nile virus (Option C):** Also a member of the *Flavivirus* genus (Group B). It is part of the Japanese Encephalitis antigenic serocomplex. **High-Yield Clinical Pearls for NEET-PG:** * **Group A (Alphaviruses):** Chikungunya, Eastern Equine Encephalitis (EEE), Western Equine Encephalitis (WEE). * **Group B (Flaviviruses):** Dengue, JE, West Nile, Yellow Fever, Kyasanur Forest Disease (KFD), and Zika. * **Vector Shortcut:** *Aedes* transmits Dengue, Chikungunya, and Yellow Fever; *Culex* transmits JE and West Nile; *Ticks* transmit KFD. * **KFD (Kyasanur Forest Disease):** Often tested as the "Monkey Fever" of Karnataka; it is a hemorrhagic *Flavivirus* transmitted by *Haemaphysalis* ticks.

Q: Herpes Zoster or Shingles represents reactivation and replication of latent infection in:

Dorsal Root Ganglion. **Explanation:** **1. Why Dorsal Root Ganglion is Correct:** Herpes Zoster (Shingles) is caused by the reactivation of the **Varicella-Zoster Virus (VZV)**. During the primary infection (Chickenpox), the virus migrates via retrograde axonal transport from the skin lesions to the sensory nerve clusters. It remains **latent** in the **Dorsal Root Ganglia (DRG)** or cranial nerve ganglia (e.g., Trigeminal ganglion). When cell-mediated immunity declines (due to age, stress, or immunosuppression), the virus reactivates, replicates, and travels down the sensory nerve to the skin, resulting in a painful, dermatomal rash. **2. Why Other Options are Incorrect:** * **Anterior Horn Cell:** These are motor neurons. VZV specifically targets sensory pathways. Involvement of anterior horn cells is rare and would result in motor weakness (Post-herpetic paresis), not the classic sensory rash. * **Peripheral Nerve:** The virus travels *through* the peripheral nerves during reactivation, but it does not remain latent there. The "niche" for latency is the neuronal cell body in the ganglion. * **Epithelium of Skin:** This is the site of active replication and clinical manifestation (vesicles), but the virus cannot remain latent in epithelial cells as they are constantly shed and replaced. **3. High-Yield Clinical Pearls for NEET-PG:** * **Tzanck Smear:** Shows **Multinucleated Giant Cells** with Cowdry Type A intranuclear inclusion bodies (common to HSV and VZV). * **Dermatomal Distribution:** Shingles characteristically does not cross the midline. The thoracic and ophthalmic (V1) dermatomes are most commonly involved. * **Hutchinson’s Sign:** Vesicles on the tip of the nose indicating involvement of the nasociliary nerve, predicting a high risk of Herpes Zoster Ophthalmicus. * **Ramsay Hunt Syndrome:** Reactivation in the **Geniculate Ganglion**, leading to facial palsy and vesicles in the external auditory canal.

Q: Giemsa stained smear of epithelial cells obtained from a newborn with hepatosplenomegaly is shown. What is the most likely cause of this congenital infection?

Cytomegalovirus (CMV). ***Cytomegalovirus (CMV)*** - Giemsa staining reveals characteristic **"owl's eye" intranuclear inclusion bodies** that are pathognomonic for CMV infection. - Congenital CMV commonly presents with **hepatosplenomegaly** as part of the TORCH complex and is the most frequent congenital viral infection. *Rubella virus* - Does not produce the distinctive **intranuclear inclusion bodies** seen on Giemsa staining. - Congenital rubella syndrome typically presents with **cataracts**, **heart defects**, and **deafness** rather than prominent hepatosplenomegaly. *Human Immunodeficiency Virus (HIV)* - HIV does not cause characteristic **cytopathic changes** visible on Giemsa-stained epithelial cells. - Congenital HIV transmission rarely presents with **hepatosplenomegaly** in the newborn period. *Epstein-Barr virus (EBV)* - EBV does not typically cause **congenital infections** or characteristic inclusion bodies on Giemsa staining. - EBV primarily affects **B-lymphocytes** and is associated with infectious mononucleosis in older children and adults.

Q: A child with agammaglobulinemia presents with respiratory tract infection and diarrhea. What is the most likely infectious agent?

Rotavirus. **Explanation:** In patients with **X-linked Agammaglobulinemia (Bruton’s)**, there is a profound deficiency of B-cells and all classes of immunoglobulins (IgG, IgA, IgM). The lack of **Secretory IgA** at mucosal surfaces makes these children highly susceptible to specific gastrointestinal and respiratory pathogens. 1. **Why Rotavirus is correct:** While these patients are classically associated with *Giardia lamblia* (due to lack of IgA), **Rotavirus** is the most common viral cause of severe diarrhea in children with agammaglobulinemia. In the absence of neutralizing antibodies, viral clearance is impaired, leading to prolonged and severe gastroenteritis. 2. **Why other options are incorrect:** * **Coxsackievirus:** While patients with agammaglobulinemia are uniquely susceptible to **Enteroviruses** (like Polio, Echovirus, and Coxsackie), these typically manifest as chronic progressive **meningoencephalitis** or dermatomyositis-like syndromes rather than isolated diarrhea. * **Shigella:** This is an invasive bacterial pathogen. While humoral immunity plays a role, the primary defect in agammaglobulinemia predisposes more significantly to encapsulated bacteria (like *S. pneumoniae* and *H. influenzae*) and specific protozoa/viruses rather than typical bacillary dysentery. **High-Yield Clinical Pearls for NEET-PG:** * **Classic Triad:** Absent B-cells (CD19/20+), absent tonsils/lymph nodes, and recurrent pyogenic infections after 6 months of age (once maternal IgG wanes). * **Most common GI parasite:** *Giardia lamblia*. * **Most common CNS complication:** Chronic Enteroviral Encephalitis. * **Contraindication:** Live vaccines (OPV, Rotavirus vaccine, MMR) are strictly contraindicated. * **Treatment:** Intravenous Immunoglobulin (IVIG) replacement.

Q: A virus produces neonatal infections and infections in immunocompromised patients such as AIDS patients. The most common clinical presentation involves floaters, visual field deficits, and painless loss of vision. It can also produce encephalitis and may cause calcifying lesions in the CNS. What is this virus most likely?

Cytomegalovirus (CMV). ### Explanation The clinical presentation described is classic for **Cytomegalovirus (CMV)**, a member of the Beta-herpesvirinae family. **Why CMV is the correct answer:** 1. **Ocular Involvement:** CMV retinitis is the most common opportunistic ocular infection in AIDS patients (typically when CD4 <50 cells/mm³). It presents with **painless vision loss**, floaters, and a characteristic "pizza-pie" appearance (hemorrhage and exudates) on fundoscopy. 2. **Congenital Infection:** CMV is the most common cause of congenital viral infection. Key features include **periventricular calcifications**, microcephaly, and sensorineural hearing loss. 3. **Immunocompromised State:** In addition to retinitis, it causes esophagitis (linear ulcers) and encephalitis in late-stage HIV. **Why other options are incorrect:** * **EBV:** Primarily associated with Infectious Mononucleosis, Oral Hairy Leukoplakia, and malignancies (Burkitt lymphoma, Nasopharyngeal carcinoma). It does not typically cause retinitis or CNS calcifications. * **HSV:** HSV-1 causes sporadic encephalitis (targeting the **temporal lobes**), but it does not cause periventricular calcifications. Neonatal HSV usually presents with skin-eye-mouth lesions or disseminated disease. * **HIV:** While HIV causes the underlying immunosuppression, the specific triad of retinitis, neonatal calcifications, and opportunistic CNS lesions points directly to the secondary pathogen, CMV. **High-Yield Clinical Pearls for NEET-PG:** * **Histology:** "Owl’s eye" intranuclear inclusion bodies. * **Congenital CMV:** Periventricular calcifications (vs. Toxoplasmosis, which shows diffuse/scattered calcifications). * **Drug of Choice:** Ganciclovir (Valganciclovir for prophylaxis). * **Culture:** Human fibroblast cell lines are used for isolation.

Q: Which of the following is associated with nasopharyngeal cancer?

Human Herpesvirus 4 (HHV-4). **Explanation:** The correct answer is **Human Herpesvirus 4 (HHV-4)**, commonly known as the **Epstein-Barr Virus (EBV)**. EBV is a potent oncogenic virus that infects B-lymphocytes and epithelial cells. Its association with **Nasopharyngeal Carcinoma (NPC)** is well-established, particularly the undifferentiated type (WHO Type III). The virus enters epithelial cells via the CD21 receptor (or through fusion) and establishes latency. Viral proteins, specifically **LMP-1 (Latent Membrane Protein 1)**, act as oncogenes by mimicking CD40 signaling, leading to cell proliferation and inhibition of apoptosis. **Analysis of Incorrect Options:** * **HHV-1 (Herpes Simplex Virus-1):** Primarily associated with orofacial lesions (herpes labialis), gingivostomatitis, and sporadic viral encephalitis. It is not oncogenic. * **HHV-2 (Herpes Simplex Virus-2):** Primarily causes genital herpes and neonatal herpes. While once studied for a link to cervical cancer, Human Papillomavirus (HPV) is the actual causative agent. * **HHV-3 (Varicella-Zoster Virus):** Causes chickenpox (primary infection) and shingles (reactivation). It does not have any known association with malignancy. **High-Yield Clinical Pearls for NEET-PG:** * **EBV-Associated Malignancies:** Apart from NPC, EBV is linked to **Burkitt Lymphoma** (starry-sky appearance, t(8;14)), Hodgkin Lymphoma (Mixed cellularity type), and Primary CNS Lymphoma in AIDS patients. * **Diagnostic Marker:** Elevated titers of **IgA antibodies against EBV Viral Capsid Antigen (VCA)** are used for screening and monitoring recurrence in NPC patients. * **Other Oncogenic Viruses:** Remember HHV-8 is associated with **Kaposi Sarcoma**, and HPV 16/18 are linked to cervical and oropharyngeal cancers.

Q: Fatal familial insomnia is associated with which type of disease?

Prion disease. **Explanation:** **Fatal Familial Insomnia (FFI)** is a rare, autosomal dominant inherited disorder caused by a mutation in the **PRNP gene** (specifically at codon 178). This mutation leads to the misfolding of the normal cellular prion protein ($PrP^C$) into an abnormal, protease-resistant isoform ($PrP^{Sc}$). These prions accumulate primarily in the **thalamus**, leading to neuronal loss and gliosis. * **Why Option A is correct:** FFI belongs to the group of **Transmissible Spongiform Encephalopathies (TSEs)** or Prion diseases. It is characterized clinically by progressive insomnia, autonomic dysfunction (tachycardia, hyperhidrosis), and motor signs, eventually leading to death. * **Why Options B, C, and D are incorrect:** While FFI involves neurodegeneration, it is specifically classified by its unique **proteinaceous infectious** etiology (Prions). It is not caused by uncontrolled cell growth (Neoplastic), ischemia/hemorrhage (Vascular), or standard age-related wear-and-tear (Degeneration) in the absence of prion proteins. **High-Yield Clinical Pearls for NEET-PG:** * **Prion Characteristics:** They are devoid of nucleic acids and resistant to standard sterilization (autoclaving at 121°C). They require **134°C for 1 hour** or 1N NaOH for disinfection. * **The "178/129" Rule:** FFI occurs when there is a mutation at **Codon 178** combined with **Methionine** at Codon 129. If Valine is present at Codon 129 with the same 178 mutation, it results in **Creutzfeldt-Jakob Disease (CJD)**. * **Other Prion Diseases:** Kuru (associated with cannibalism), Gerstmann-Sträussler-Scheinker (GSS) syndrome, and Bovine Spongiform Encephalopathy (Mad Cow Disease).

Q: Elevated IgG and IgM antibody titers to parvovirus suggest a diagnosis of which one of the following?

Fifth disease. **Explanation:** The presence of elevated **IgM and IgG antibodies** to Parvovirus B19 is diagnostic of a recent or ongoing infection. In clinical practice, IgM appears within 10 days of exposure and persists for 2–3 months, indicating an **acute infection**, while IgG appears shortly after and provides lifelong immunity. **Why Fifth Disease is correct:** Parvovirus B19 is the causative agent of **Fifth disease** (Erythema Infectiosum). It typically presents in children with a characteristic "slapped-cheek" rash followed by a reticular (lace-like) rash on the trunk and limbs. The virus targets **erythroid progenitor cells** by binding to the **P-antigen** (globoside) on the cell surface. **Analysis of Incorrect Options:** * **A. Acute Lyme Disease:** Caused by the spirochete *Borrelia burgdorferi*. Diagnosis is based on clinical findings (Erythema migrans) and serology for Borrelia, not Parvovirus. * **C. Hepatitis B Infection:** Caused by the Hepatitis B virus (HBV). Diagnosis relies on markers like HBsAg, anti-HBc IgM, and HBV DNA. * **D. Subacute Sclerosing Panencephalitis (SSPE):** A rare, progressive neurological complication caused by a persistent **Measles virus** infection, characterized by high titers of anti-measles antibodies in the CSF and serum. **High-Yield Clinical Pearls for NEET-PG:** * **Aplastic Crisis:** Parvovirus B19 can cause a transient cessation of erythropoiesis, which is life-threatening in patients with high red cell turnover (e.g., **Sickle Cell Anemia**, Hereditary Spherocytosis). * **Hydrops Fetalis:** Infection during pregnancy can lead to severe fetal anemia, high-output cardiac failure, and fetal death. * **Arthropathy:** In adults, infection often presents as symmetrical small joint arthritis (mimicking Rheumatoid Arthritis). * **Receptor:** The cellular receptor for Parvovirus B19 is the **P-antigen**.

Question 1

Which of the following viruses does NOT belong to Group B arboviruses?

Accepted Answer

Chikungunya virus

Answer

Dengue virus

Answer

Japanese encephalitis virus

Answer

West Nile virus

Question 2

Herpes Zoster or Shingles represents reactivation and replication of latent infection in:

Accepted Answer

Dorsal Root Ganglion

Answer

Anterior Horn Cell

Answer

Peripheral nerve

Answer

Epithelium of Skin

Question 3

Giemsa stained smear of epithelial cells obtained from a newborn with hepatosplenomegaly is shown. What is the most likely cause of this congenital infection?

Accepted Answer

Cytomegalovirus (CMV)

Answer

Rubella virus

Answer

Human Immunodeficiency Virus (HIV)

Answer

Epstein-Barr virus (EBV)

Question 4

A child with agammaglobulinemia presents with respiratory tract infection and diarrhea. What is the most likely infectious agent?

Accepted Answer

Rotavirus

Answer

Cocksackie virus

Answer

Shigella

Answer

None of the above

Question 5

A virus produces neonatal infections and infections in immunocompromised patients such as AIDS patients. The most common clinical presentation involves floaters, visual field deficits, and painless loss of vision. It can also produce encephalitis and may cause calcifying lesions in the CNS. What is this virus most likely?

Accepted Answer

Cytomegalovirus (CMV)

Answer

Epstein-Barr Virus (EBV)

Answer

Herpes Simplex Virus (HSV)

Answer

Human Immunodeficiency Virus (HIV)

Question 6

A 65-year-old patient with chronic obstructive airway disease presented with headache, rhinorrhoea, myalgia, and retro-orbital and throat pain. He was managed conservatively. After 3-4 days, he presented again with cough, fever, and severe dyspnoea, requiring oxygen therapy. His condition deteriorated further, and ABG analysis showed pH 7.42, pCO2 41 mm Hg, pO2 34 mm Hg, and HCO3- 26 mmol/L. Blood cultures and sputum samples were negative for bacterial infections. Which of the following statements about the causative organism of this condition is FALSE?

Accepted Answer

Haemolysins are present.

Answer

The organism is mostly spherical but filamentous in fresh isolates.

Answer

The organism is segmented with 8 pieces of RNA.

Answer

The diameter of the nucleocapsid is 9nm.

Question 7

Which of the following is associated with nasopharyngeal cancer?

Accepted Answer

Human Herpesvirus 4 (HHV-4)

Answer

Human Herpesvirus 1 (HHV-1)

Answer

Human Herpesvirus 2 (HHV-2)

Answer

Human Herpesvirus 3 (HHV-3)

Question 8

Fatal familial insomnia is associated with which type of disease?

Accepted Answer

Prion disease

Answer

Degeneration disease

Answer

Neoplastic disease

Answer

Vascular disease

Question 9

All are true about hepatitis viruses EXCEPT?

Accepted Answer

Hepatitis A virus (HAV) leads to most cases of fulminant hepatitis.

Answer

Hepatitis C virus (HCV) leads to chronic liver disease.

Answer

Hepatitis A virus (HAV) is transmitted via the fecal-oral route.

Answer

Hepatitis B virus (HBV) can cause hepatocellular carcinoma.

Question 10

Elevated IgG and IgM antibody titers to parvovirus suggest a diagnosis of which one of the following?

Accepted Answer

Fifth disease

Answer

Acute Lyme disease

Answer

Possible hepatitis B infection

Answer

Possible subacute sclerosing panencephalitis

Virology — MCQs

Virology — MCQs

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