Virology Practice Questions

Q: A 27-year-old man with a history of intravenous drug use has been infected with the hepatitis B virus for the past 6 years and has not been ill. He presents with nausea, vomiting, and passage of dark-colored urine for the past week. Physical examination reveals scleral icterus and mild jaundice. Neurologic examination shows a confused, somnolent man oriented only to person. He exhibits asterixis. Laboratory studies show total protein, 5 g/dL; albumin, 2.7 g/dL; AST, 2342 U/L; ALT, 2150 U/L; alkaline phosphatase, 233 U/L; total bilirubin, 8.3 mg/dL; and direct bilirubin, 4.5 mg/dL. Superinfection with which of the following viruses has most likely occurred in this man?

Hepatitis D virus (HDV). ### Explanation **Correct Answer: C. Hepatitis D virus (HDV)** The patient is a chronic carrier of Hepatitis B Virus (HBV) who has developed **Fulminant Hepatic Failure (FHF)**, evidenced by severe transaminitis (AST/ALT >2000 U/L), hyperbilirubinemia, and **hepatic encephalopathy** (confusion, asterixis, somnolence). In a known HBV carrier, a sudden clinical deterioration usually points toward **HDV superinfection**. HDV is a defective RNA virus that requires the HBsAg coat to infect hepatocytes. When a chronic HBV carrier is infected with HDV (superinfection), it often leads to severe acute hepatitis, a higher risk of fulminant liver failure, and rapid progression to cirrhosis compared to co-infection (simultaneous infection of HBV and HDV). **Why other options are incorrect:** * **HAV & HEV:** These are transmitted via the fecal-oral route. While they cause acute hepatitis, they do not specifically target HBV carriers nor typically cause such dramatic deterioration in a patient with a high-risk profile (IV drug use). * **HCV:** While common in IV drug users, HCV rarely causes fulminant hepatitis. It typically leads to chronic infection rather than an acute, life-threatening presentation with encephalopathy. **NEET-PG High-Yield Pearls:** * **Co-infection:** HBV + HDV acquired at the same time. Usually self-limiting; 80% risk of chronic HDV infection. * **Marker of HDV:** HDAg and HDV RNA are the earliest markers. * **Asterixis (Flapping tremors):** A hallmark sign of Stage II hepatic encephalopathy due to ammonia accumulation.

Q: Regarding hepatitis E, which of the following statements is true?

It increases mortality in pregnant individuals.. **Explanation:** **Hepatitis E Virus (HEV)** is a major cause of enterically transmitted hepatitis worldwide. The correct answer is **Option D** because HEV infection in pregnant individuals, particularly during the third trimester, is associated with a high risk of **Fulminant Hepatic Failure (FHF)**. The mortality rate in this demographic can reach as high as **15–25%**, likely due to a combination of hormonal changes and altered immune responses (Th2 bias). **Analysis of Incorrect Options:** * **Option A:** Hepatitis **D** (not E) is the virus that requires Hepatitis B surface antigen (HBsAg) for its envelope and occurs as a co-infection or super-infection with HBV. * **Option B:** HEV is a **non-enveloped, single-stranded RNA virus** belonging to the *Hepeviridae* family. It is not a DNA virus. * **Option C:** While HEV can cause chronic infection in immunocompromised patients (like those with HIV or organ transplants), it is not classically defined by a frequent epidemiological association with HIV in the same way that HBV or HCV (blood-borne) are. **High-Yield Clinical Pearls for NEET-PG:** * **Transmission:** Fecal-oral route (contaminated water is the most common vehicle). * **Zoonosis:** HEV Genotype 3 is associated with the consumption of undercooked pork/deer meat. * **Chronicity:** HEV usually causes acute self-limiting hepatitis, but **Genotype 3** can cause chronic hepatitis in immunocompromised individuals. * **Diagnosis:** Detection of IgM anti-HEV or HEV RNA by PCR. * **Key Association:** Always link "Hepatitis E" with "High mortality in pregnancy" and "Water-borne epidemics."

Q: Transient erythroid hypoplasia in hereditary spherocytosis is caused by?

Parvovirus B19. **Explanation:** The correct answer is **Parvovirus B19**. **Mechanism of Action:** Parvovirus B19 is a DNA virus that specifically targets and destroys **erythroid progenitor cells** in the bone marrow by binding to the **P-antigen** (globoside) on their surface [1]. In healthy individuals, this causes a mild, transient drop in hemoglobin that is clinically insignificant. However, in patients with high red cell turnover (e.g., **Hereditary Spherocytosis**, Sickle Cell Anemia, or Thalassemia), the bone marrow is already working at maximum capacity to compensate for hemolysis [1]. When Parvovirus B19 halts erythropoiesis, it leads to a sudden, severe drop in hemoglobin and a low reticulocyte count, a condition known as an **Aplastic Crisis** [1]. **Analysis of Incorrect Options:** * **A. Epstein-Barr Virus (EBV):** Primarily causes Infectious Mononucleosis. While it can cause autoimmune hemolytic anemia (AIHA), it does not typically cause transient erythroid hypoplasia. * **C. Cytomegalovirus (CMV):** Generally causes asymptomatic infection or mononucleosis-like syndrome in immunocompetent hosts and multisystem organ disease in immunocompromised patients, but not specific erythroid hypoplasia. * **D. Hepatitis B Virus (HBV):** Associated with extrahepatic manifestations like Polyarteritis Nodosa (PAN) and Membranous Glomerulonephritis, but not acute aplastic crises in hemolytic anemia. **High-Yield Clinical Pearls for NEET-PG:** * **Hallmark of Aplastic Crisis:** Anemia + **Reticulocytopenia** (distinguishes it from a hyperhemolytic crisis where reticulocytes are high) [1]. * **Fifth Disease:** In children, Parvovirus B19 causes **Erythema Infectiosum**, characterized by a "slapped-cheek" rash [1]. * **Hydrops Fetalis:** Parvovirus B19 infection in pregnancy can lead to severe fetal anemia and high-output heart failure. * **Diagnosis:** Detection of IgM antibodies or PCR for viral DNA.

Q: Which of the following is a prion disease?

Creutzfeldt-Jacob disease. **Explanation:** **Prion diseases**, also known as Transmissible Spongiform Encephalopathies (TSEs), are caused by **prions**—infectious proteinaceous particles that lack nucleic acids. They occur when the normal cellular protein ($PrP^C$) undergoes a conformational change into a misfolded, protease-resistant isoform ($PrP^{Sc}$). **Correct Option: A. Creutzfeldt-Jakob Disease (CJD)** CJD is the most common human prion disease. It is characterized by rapidly progressive dementia, myoclonus, and a "spongiform" appearance of the brain (vacuolation of neurons and gray matter) without inflammation. It can be sporadic (most common), familial, or acquired (variant CJD). **Incorrect Options:** * **B. Subacute Sclerosing Panencephalitis (SSPE):** This is a progressive neurological disorder caused by a persistent infection with a **defective Measles virus**, not a prion. It typically occurs years after the initial measles infection. * **C & D. Alzheimer’s and Parkinson’s Diseases:** While these are "protein-misfolding" neurodegenerative disorders (involving Amyloid-beta/Tau and Alpha-synuclein, respectively), they are **not** classified as infectious prion diseases or TSEs. **High-Yield Clinical Pearls for NEET-PG:** * **Diagnosis:** The presence of **14-3-3 protein** in CSF is a key biochemical marker for CJD. * **EEG Finding:** Characterized by **periodic sharp wave complexes (PSWCs)**. * **Kuru:** Another human prion disease associated with ritualistic cannibalism. * **Sterilization:** Prions are highly resistant; they require **autoclaving at 134°C** or immersion in **1N Sodium Hydroxide (NaOH)** for 1 hour for inactivation. Normal boiling or standard disinfectants are ineffective.

Q: Which virus cannot be cultivated in laboratory settings?

Molluscum contagiosum virus. **Explanation:** The correct answer is **Molluscum contagiosum virus (MCV)**. **1. Why Molluscum contagiosum is the correct answer:** Molluscum contagiosum virus, a member of the *Poxviridae* family, is unique because it **cannot be cultivated** in routine laboratory settings, including cell cultures, embryonated eggs, or common animal models. This is due to its highly specialized requirement for human epidermal keratinocytes and its inability to complete its replication cycle in standard laboratory media. Diagnosis is therefore primarily clinical or based on histopathology (identifying Henderson-Patterson bodies). **2. Analysis of Incorrect Options:** * **A. Vaccinia virus:** This virus is highly robust and grows easily in various cell lines and on the chorioallantoic membrane (CAM) of embryonated eggs. It was famously used as the live vaccine for smallpox eradication. * **B. Variola virus:** The causative agent of smallpox can be cultivated on the CAM of embryonated eggs, where it produces characteristic small, white, non-hemorrhagic pocks. (Note: It is now restricted to high-security WHO labs). * **C. Cowpox virus:** Like Vaccinia, Cowpox grows well in the laboratory and produces large, hemorrhagic pocks on the CAM. **3. High-Yield Clinical Pearls for NEET-PG:** * **Henderson-Patterson Bodies:** Pathognomonic large, eosinophilic intracytoplasmic inclusion bodies seen in MCV. * **Clinical Presentation:** Characterized by pearly, flesh-colored, **umbilicated papules**. * **Poxvirus Replication:** Unlike most DNA viruses, Poxviruses replicate entirely in the **cytoplasm** because they carry their own DNA-dependent RNA polymerase. * **Guarnieri Bodies:** Inclusion bodies associated with Variola and Vaccinia.

Q: Which of the following conditions is NOT caused by EBV?

Castleman's disease. **Explanation:** The correct answer is **D. Castleman’s disease**. Castleman’s disease (specifically the multicentric type) is primarily associated with **Human Herpesvirus 8 (HHV-8)**, also known as Kaposi Sarcoma-associated Herpesvirus (KSHV), rather than Epstein-Barr Virus (EBV). HHV-8 produces a viral homolog of Interleukin-6 (vIL-6), which drives the characteristic lymphoproliferation seen in this condition. **Analysis of Incorrect Options:** * **Duncan’s syndrome (X-linked Lymphoproliferative Disease):** This is a rare genetic disorder where an extreme, often fatal, immune response occurs following an **EBV infection**. It is characterized by fulminant infectious mononucleosis and B-cell lymphomas. * **Kissing disease (Infectious Mononucleosis):** This is the classic clinical presentation of primary **EBV infection**, typically seen in adolescents. It presents with the triad of fever, pharyngitis, and lymphadenopathy, along with atypical lymphocytosis (Downey cells). * **Non-Hodgkin’s Lymphoma (NHL):** EBV is a potent oncogenic virus. It is strongly linked to several types of NHL, most notably **Burkitt Lymphoma** (starry-sky appearance) and B-cell lymphomas in immunocompromised patients (e.g., HIV/AIDS). **High-Yield Clinical Pearls for NEET-PG:** * **EBV Associations:** Nasopharyngeal carcinoma, Oral Hairy Leukoplakia (in HIV), and Hodgkin’s Lymphoma (Mixed cellularity subtype). * **Diagnosis:** Monospot test (detects heterophile antibodies) is the screening test of choice. * **Receptor:** EBV enters B-cells via the **CD21** receptor (also known as CR2). * **HHV-8 Associations:** Kaposi Sarcoma, Primary Effusion Lymphoma, and Multicentric Castleman’s Disease.

Q: Which of the following hepatitis viruses replicates its genome in the nucleus of the host hepatocyte?

Hepatitis B virus (HBV). ### Explanation **Correct Answer: A. Hepatitis B virus (HBV)** **Why it is correct:** Hepatitis B virus (HBV) is a **Hepadnavirus** and is the only DNA virus among the common hepatitis viruses. Its replication cycle is unique: after entering the hepatocyte, the partially double-stranded relaxed circular DNA (rcDNA) is transported to the **nucleus**. Here, it is converted into **covalently closed circular DNA (cccDNA)**, which serves as the template for transcription by host RNA polymerase II. Although HBV uses reverse transcription (via RNA intermediate) to replicate its genome, the initial stabilization and transcription of its genetic material occur strictly within the host nucleus. **Why the other options are incorrect:** * **Hepatitis A (HAV), C (HCV), and E (HEV):** These are all **RNA viruses** (Picornavirus, Flavivirus, and Hepevirus, respectively). Unlike DNA viruses, most RNA viruses (except Influenza and Retroviruses) replicate entirely within the **cytoplasm** of the host cell, utilizing their own RNA-dependent RNA polymerase. They do not require the host nuclear machinery for genome replication. **High-Yield Clinical Pearls for NEET-PG:** * **cccDNA:** This is the "latent" form of HBV in the nucleus; it is responsible for viral persistence and is the reason why current treatments (Nucleoside analogs) can suppress but rarely "cure" HBV. * **Reverse Transcriptase:** HBV is a DNA virus that replicates via an RNA intermediate using reverse transcriptase (contained within the core). * **Dane Particle:** The 42 nm complete infectious virion of HBV. * **Hepatitis D (HDV):** A defective RNA virus that requires the HBsAg coating from HBV for its assembly and transmission.

Q: Which of the following is true about Creutzfeldt-Jakob disease?

It is caused by a DNA-containing organism. **Explanation:** Creutzfeldt-Jakob Disease (CJD) is a fatal neurodegenerative disorder belonging to the group of **Transmissible Spongiform Encephalopathies (TSEs)**. **Why Option C is the "Correct" Answer (in the context of the question):** It is important to note that CJD is caused by **Prions**, which are unique infectious agents composed entirely of protein (**PrPSc**). Prions are characterized by the **complete absence of nucleic acids** (neither DNA nor RNA). Therefore, Option C is technically a "false" statement. In many medical entrance exams, questions may ask for the "true" statement but provide options where the intended answer is based on identifying the pathogen's nature. If this question follows the pattern where Option C is marked correct, it is likely a "except" style question or a common error in older question banks. **Factually, CJD is NOT caused by a DNA-containing organism.** **Analysis of Other Options:** * **Option A (Inheritable):** While most cases (85%) are sporadic, **Familial CJD** exists due to mutations in the PRNP gene, making it inheritable. * **Option B (Corneal implants):** This is a **True** statement. CJD can be transmitted iatrogenically via corneal transplants, dura mater grafts, and contaminated neurosurgical instruments. * **Option D (Arthropod-borne):** CJD is not transmitted by insects; it is transmitted via ingestion, medical procedures, or genetics. **High-Yield Clinical Pearls for NEET-PG:** * **Pathogenesis:** Misfolding of normal cellular protein (PrPc) into the beta-pleated sheet form (PrPSc). * **Resistance:** Prions are highly resistant to standard sterilization (autoclaving, UV, formalin). They require **1N NaOH or 5% Sodium Hypochlorite** for 1 hour. * **Diagnosis:** Characterized by **rapidly progressive dementia**, myoclonus, and "periodic sharp wave complexes" on EEG. * **Histology:** Spongiform vacuolation of neurons without inflammation.

Q: Which of the following viruses produces both intranuclear and intracytoplasmic inclusion bodies?

Measles virus. ### Explanation The correct answer is **Measles virus (Morbillivirus)**. In virology, inclusion bodies are distinct structures formed during viral replication, representing either "viral factories" or remnants of host cell damage. Most DNA viruses produce intranuclear inclusions (except Poxvirus), while most RNA viruses produce intracytoplasmic inclusions. **Measles virus** is a unique exception among RNA viruses. It belongs to the Paramyxoviridae family and produces **both intranuclear and intracytoplasmic inclusion bodies**. These are known as **Warthin-Finkeldey cells**, which are pathognomonic multinucleated giant cells containing these inclusions. #### Analysis of Incorrect Options: * **Chickenpox virus (Varicella-Zoster):** As a Herpesvirus (DNA virus), it produces only **intranuclear** inclusion bodies, specifically the **Cowdry Type A** (acidophilic) inclusions. * **Rabies virus:** An RNA virus that produces only **intracytoplasmic** inclusion bodies known as **Negri bodies**, typically found in the Purkinje cells of the cerebellum and pyramidal cells of the hippocampus. * **Smallpox virus (Variola):** Although it is a DNA virus, it replicates in the cytoplasm. It produces only **intracytoplasmic** inclusion bodies called **Guarnieri bodies**. #### High-Yield Clinical Pearls for NEET-PG: * **Both Intranuclear & Intracytoplasmic:** Measles and Cytomegalovirus (CMV). *Note: CMV is famous for "Owl’s eye" intranuclear inclusions, but it can also show cytoplasmic ones.* * **Cowdry Type A (Intranuclear):** Herpes Simplex Virus (HSV), Varicella-Zoster Virus (VZV), and Yellow Fever (Torres bodies). * **Cowdry Type B (Intranuclear):** Poliovirus and Adenovirus. * **Henderson-Patterson Bodies:** Intracytoplasmic inclusions seen in Molluscum Contagiosum.

Question 1

Which of the following best describes adenovirus?

Accepted Answer

Nonenveloped, double-stranded DNA virus with fibers at its vertices

Answer

Nonenveloped, double-stranded, circular DNA virus

Answer

Enveloped, single-stranded, negative-sense RNA virus

Answer

Enveloped, double-stranded, linear DNA virus with glycoprotein spikes

Question 2

A 27-year-old man with a history of intravenous drug use has been infected with the hepatitis B virus for the past 6 years and has not been ill. He presents with nausea, vomiting, and passage of dark-colored urine for the past week. Physical examination reveals scleral icterus and mild jaundice. Neurologic examination shows a confused, somnolent man oriented only to person. He exhibits asterixis. Laboratory studies show total protein, 5 g/dL; albumin, 2.7 g/dL; AST, 2342 U/L; ALT, 2150 U/L; alkaline phosphatase, 233 U/L; total bilirubin, 8.3 mg/dL; and direct bilirubin, 4.5 mg/dL. Superinfection with which of the following viruses has most likely occurred in this man?

Accepted Answer

Hepatitis D virus (HDV)

Answer

Hepatitis A virus (HAV)

Answer

Hepatitis C virus (HCV)

Answer

Hepatitis E virus (HEV)

Question 3

Regarding hepatitis E, which of the following statements is true?

Accepted Answer

It increases mortality in pregnant individuals.

Answer

It commonly occurs with Hepatitis B co-infection.

Answer

It is caused by a single-stranded DNA virus.

Answer

It frequently occurs along with HIV co-infection.

Question 4

Transient erythroid hypoplasia in hereditary spherocytosis is caused by?

Accepted Answer

Parvovirus B19

Answer

Epstein Barr virus

Answer

Cytomegalovirus

Answer

Hepatitis B virus

Question 5

Which of the following is a prion disease?

Accepted Answer

Creutzfeldt-Jacob disease

Answer

Subacute sclerosing panencephalitis

Answer

Alzheimer's disease

Answer

Parkinson disease

Question 6

Which virus cannot be cultivated in laboratory settings?

Accepted Answer

Molluscum contagiosum virus

Answer

Vaccinia virus

Answer

Variola virus

Answer

Cowpox virus

Question 7

Which of the following conditions is NOT caused by EBV?

Accepted Answer

Castleman's disease

Answer

Duncan's syndrome

Answer

Kissing disease

Answer

Non-Hodgkin's Lymphoma

Question 8

Which of the following hepatitis viruses replicates its genome in the nucleus of the host hepatocyte?

Accepted Answer

Hepatitis B virus (HBV)

Answer

Hepatitis C virus (HCV)

Answer

Hepatitis E virus (HEV)

Answer

Hepatitis A virus (HAV)

Question 9

Which of the following is true about Creutzfeldt-Jakob disease?

Accepted Answer

It is caused by a DNA-containing organism

Answer

It is an inheritable disease

Answer

Corneal implants can transmit the disease

Answer

It is an arthropod-borne disease

Question 10

Which of the following viruses produces both intranuclear and intracytoplasmic inclusion bodies?

Accepted Answer

Measles virus

Answer

Chickenpox virus

Answer

Rabies virus

Answer

Smallpox virus

Virology — MCQs

Virology — MCQs

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