Virology Practice Questions

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

Flavivirus. **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.

Q: Which of the following viruses does NOT cause pneumonia?

Mumps virus. **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.

Q: A patient's serum shows HbsAg and IgM to Hbc. What is the diagnosis?

Acute hepatitis. To understand the diagnosis of Hepatitis B, one must interpret the "Serological Window." **1. Why Option B is Correct:** The presence of **HBsAg** (Hepatitis B surface Antigen) indicates that the virus is currently present in the body. The presence of **IgM anti-HBc** (Immunoglobulin M antibody to Hepatitis B core antigen) is the hallmark of a **recent/acute infection** (typically within the last 6 months). When both are positive, it confirms a diagnosis of **Acute Hepatitis B**. **2. Why the other options are incorrect:** * **Options A & D (Chronic Hepatitis B):** In chronic infection, HBsAg persists for more than 6 months, but the body switches from producing IgM to **IgG anti-HBc**. Therefore, the presence of IgM specifically rules out chronicity. * **Option C (Acute Hepatitis C):** This is incorrect because HBsAg and anti-HBc are specific biomarkers for the Hepatitis B virus (HBV), not Hepatitis C (HCV). HCV diagnosis would require HCV RNA or Anti-HCV antibodies. **3. NEET-PG High-Yield Pearls:** * **Window Period:** This is the interval where HBsAg has disappeared but Anti-HBs has not yet appeared. During this time, **IgM anti-HBc** is the *only* positive marker (the "Window Marker"). * **HBeAg:** Indicates high viral replication and high infectivity. * **Anti-HBs:** Its presence indicates immunity (either via recovery or vaccination). * **Vaccination Profile:** A vaccinated individual will be positive for **Anti-HBs** only (negative for HBsAg and Anti-HBc).

Q: Lymphocytosis with atypical lymphocytes is seen in infection with which of the following viruses?

Epstein-Barr Virus (EBV). ### Explanation **Correct Answer: C. Epstein-Barr Virus (EBV)** **Why it is correct:** Epstein-Barr Virus (EBV) is the primary causative agent of **Infectious Mononucleosis (IM)**. The hallmark of this condition is absolute lymphocytosis where more than 10% of the lymphocytes are **atypical lymphocytes**, also known as **Downey cells**. The underlying medical concept is crucial: EBV infects B-cells via the **CD21 receptor**. However, the "atypical lymphocytes" seen on a peripheral blood smear are actually **activated CD8+ T-cells (Cytotoxic T-cells)** reacting against the EBV-infected B-cells. These cells are larger than normal lymphocytes, possess abundant cytoplasm, and have a "ballerina skirt" appearance as they indent around neighboring red blood cells. **Why the other options are incorrect:** * **A. HSV:** Typically causes localized vesicular lesions (cold sores or genital herpes). While it can cause systemic symptoms, it does not characteristically produce a peripheral smear dominated by atypical lymphocytosis. * **B. HBV:** Primarily targets hepatocytes. While it involves immune-mediated liver injury, the hematological profile does not typically feature Downey cells. * **D. RSV:** A major cause of bronchiolitis and pneumonia in infants. It is characterized by respiratory distress and syncytia formation in lung tissue, not systemic atypical lymphocytosis. **NEET-PG High-Yield Pearls:** * **Paul-Bunnell Test:** Detects heterophile antibodies; used for rapid diagnosis of EBV. * **Differential Diagnosis:** Cytomegalovirus (CMV) also causes a "mononucleosis-like syndrome" with atypical lymphocytes, but it is **Heterophile Antibody Negative**. * **Associated Malignancies:** EBV is linked to Burkitt Lymphoma (t 8;14), Nasopharyngeal Carcinoma, and Hodgkin Lymphoma. * **Clinical Triad of IM:** Fever, Pharyngitis, and Lymphadenopathy (posterior cervical). Splenomegaly is also a common finding.

Q: Which of the following viral infections is characterized by the presence of inclusion bodies in neurons?

Rabies. ### Explanation **Correct Answer: A. Rabies** Rabies is a neurotropic viral infection caused by the *Lyssavirus* (Rhabdoviridae family). The hallmark histopathological finding is the **Negri body**. These are pathognomonic, eosinophilic, intracytoplasmic inclusion bodies found within the cytoplasm of neurons, 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 (nucleocapsid accumulation). **Analysis of Incorrect Options:** * **B. Diphtheria:** This is a bacterial infection caused by *Corynebacterium diphtheriae*. It produces an exotoxin that inhibits protein synthesis. While it can cause neurological symptoms (polyneuropathy) due to demyelination, it does not produce viral inclusion bodies. * **C. Yellow Fever:** This is a flavivirus infection. Its characteristic inclusion bodies are **Councilman bodies**, which are eosinophilic globules found in the **hepatocytes** (liver), representing apoptotic hepatocytes, not neurons. * **D. Japanese Encephalitis (JE):** While JE is a neurotropic flavivirus that causes severe inflammation of the brain parenchyma, it does not typically present with well-defined, diagnostic inclusion bodies like Rabies. Diagnosis relies on IgM ELISA in CSF/Serum. **High-Yield Clinical Pearls for NEET-PG:** * **Negri Bodies:** Intracytoplasmic, eosinophilic, found in neurons (Hippocampus/Cerebellum). * **Guarnieri Bodies:** Intracytoplasmic; seen in Variola (Smallpox) and Vaccinia. * **Cowdry Type A:** Intranuclear; seen in Herpes Simplex Virus (HSV) and Varicella-Zoster Virus (VZV). * **Cowdry Type B:** Intranuclear; seen in Poliovirus. * **Owl’s Eye Appearance:** Intranuclear inclusions seen in Cytomegalovirus (CMV). * **Henderson-Peterson Bodies:** Intracytoplasmic; seen in Molluscum contagiosum.

Q: Which virus has a single-stranded RNA genome with segmented genes?

Influenza virus. **Explanation:** The correct answer is **Influenza virus**. The fundamental concept here is the classification of viral genomes based on their nucleic acid structure and segmentation. **1. Why Influenza Virus is Correct:** Influenza viruses (Orthomyxoviridae) possess a **single-stranded RNA (ssRNA)** genome that is **segmented**. Influenza A and B typically have 8 segments, while Influenza C has 7. This segmentation is clinically critical because it allows for **genetic reassortment** (Antigenic Shift) when two different strains infect the same cell, leading to pandemics. **2. Why the Other Options are Incorrect:** * **Rotavirus & Reovirus:** While these viruses have **segmented** genomes, they consist of **double-stranded RNA (dsRNA)**, not single-stranded. Rotavirus (a member of the Reoviridae family) typically has 11 segments. * **Measles Virus:** This is a member of the Paramyxoviridae family. It has a **single-stranded RNA** genome, but it is **non-segmented** (unipartite). **3. NEET-PG High-Yield Pearls:** * **Mnemonic for Segmented Viruses:** "**BOAR**" — **B**unyavirus, **O**rthomyxovirus (Influenza), **A**renavirus, and **R**eovirus. * **Antigenic Shift vs. Drift:** Segmentation allows for **Shift** (major changes/pandemics via reassortment). Point mutations cause **Drift** (minor changes/epidemics). * **Replication Exception:** Unlike most RNA viruses that replicate in the cytoplasm, **Influenza virus** replicates its genome in the **nucleus**. * **Amantadine/Rimantadine** target the M2 ion channel (only in Influenza A), while **Oseltamivir/Zanamivir** are Neuraminidase inhibitors effective against both A and B.

Q: SSPE is a rare complication of which viral infection?

Measles. **Explanation:** **Subacute Sclerosing Panencephalitis (SSPE)**, also known as Dawson disease, is a progressive, fatal neurodegenerative disease caused by a persistent infection with a **defective Measles virus**. **Why Measles is Correct:** SSPE occurs years (typically 5–10) after an initial measles infection, usually in children who contracted the virus before age two. The underlying mechanism involves a mutated measles virus that lacks the **M (Matrix) protein**, preventing the virus from budding. Instead, it spreads directly from cell to cell via syncytia formation, leading to widespread inflammation and demyelination in the CNS. **Analysis of Incorrect Options:** * **Mumps:** While mumps can cause acute viral meningitis or encephalitis, it does not lead to a chronic, progressive sclerosing panencephalitis like SSPE. * **Rubella:** Rubella is associated with **Progressive Rubella Panencephalitis (PRP)**, which is clinically similar to SSPE but much rarer and caused by the Rubella virus, not Measles. * **Influenza:** Influenza is associated with acute neurological complications like Reye Syndrome (if aspirin is used) or acute necrotizing encephalopathy, but not chronic persistent CNS infections. **High-Yield Clinical Pearls for NEET-PG:** * **Diagnosis:** Characterized by high titers of **anti-measles antibodies** in the CSF and serum (intrathecal synthesis). * **EEG Finding:** Pathognomonic **periodic, high-voltage slow-wave complexes** (Radermecker complexes). * **Histology:** Presence of **Cowdry Type A** intranuclear inclusion bodies in neurons and glial cells. * **Clinical Stages:** Progresses from behavioral changes to myoclonic jerks, followed by dementia and eventually a vegetative state.

Q: Which of the following statements is true regarding chickenpox?

The virus is not found in the scabs.. **Explanation:** Chickenpox is caused by the **Varicella-Zoster Virus (VZV)**, a member of the *Herpesviridae* family. Understanding its transmission and virology is crucial for NEET-PG. **1. Why Option A is Correct:** The Varicella-Zoster virus is highly fragile and thermolabile. While the virus is present in high concentrations in the **vesicular fluid** and upper respiratory secretions, it is **not found in the scabs (crusts)**. The scabs consist of dried exudate and dead epithelial cells; by the time a lesion reaches the crusting stage, the virus has been inactivated. Therefore, a patient is no longer infectious once all lesions have crusted over. **2. Why the other options are Incorrect:** * **Option B:** Unlike many other viruses (like Influenza), VZV **cannot be grown on chick embryos**. It is highly host-specific and is typically cultured in human diploid cell lines (e.g., WI-38 or MRC-5). * **Option C:** VZV is a **DNA virus** (specifically, a double-stranded, enveloped DNA virus), not an RNA virus. * **Option D:** VZV **can cross the placental barrier**. Infection in the first 20 weeks of pregnancy can lead to **Congenital Varicella Syndrome** (characterized by cicatricial skin scarring, limb hypoplasia, and chorioretinitis). **Clinical Pearls for NEET-PG:** * **Secondary Attack Rate:** Very high (~90%) among susceptible household contacts. * **Incubation Period:** Usually 14–16 days (Range: 10–21 days). * **Period of Communicability:** 1–2 days before the appearance of the rash until all lesions have crusted (usually 4–5 days after rash onset). * **Rash Pattern:** Centripetal distribution (more on trunk) and "pleomorphic" (all stages of rash—papules, vesicles, and crusts—seen simultaneously). * **Dew-drop on a rose petal:** Classic description of the varicella vesicle.

Q: Which of the following infections is not documented to be spread by sexual contact?

Hepatitis E Virus (HEV). ### Explanation The correct answer is **Hepatitis E Virus (HEV)**. **1. Why Hepatitis E (HEV) is the correct answer:** Hepatitis E is primarily transmitted via the **fecal-oral route**, most commonly through contaminated drinking water. Unlike other hepatitis viruses, there is currently **no documented evidence** of HEV transmission through sexual contact. It is characterized by epidemic outbreaks in developing countries and carries a high mortality rate (up to 20%) specifically in pregnant women. **2. Why the other options are incorrect:** * **Hepatitis B (HBV):** This is a classic sexually transmitted infection (STI). It is found in high concentrations in blood, semen, and vaginal secretions. Sexual contact is a major route of transmission globally. * **Hepatitis C (HCV):** While primarily blood-borne (parenteral), sexual transmission of HCV is documented, particularly among men who have sex with men (MSM) and individuals with multiple sexual partners or co-infection with HIV. * **Hepatitis A (HAV):** Although primarily fecal-oral, HAV is well-documented to spread via **sexual contact**, specifically through oral-anal contact (anilingus). Outbreaks are frequently reported in the MSM community. **3. NEET-PG High-Yield Pearls:** * **Vowels (A & E):** Transmitted by the **Enteric** route (Fecal-oral). * **Consonants (B, C, D):** Transmitted by **Blood** and Body fluids (Parenteral/Sexual). * **Exception to remember:** While both A and E are enteric, **only A** is significantly associated with sexual transmission (oral-anal). * **Pregnancy & HEV:** Always remember the association of HEV with **Fulminant Hepatic Failure** in the third trimester of pregnancy. * **HCV:** Has the highest risk of progressing to **chronic** hepatitis and cirrhosis.

Question 1

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

Accepted Answer

Flavivirus

Answer

Myxovirus

Answer

Alphavirus

Answer

Phlebovirus

Question 2

Which of the following viruses does NOT cause pneumonia?

Accepted Answer

Mumps virus

Answer

Cytomegalovirus

Answer

Measles virus

Answer

Retrovirus

Question 3

A patient's serum shows HbsAg and IgM to Hbc. What is the diagnosis?

Accepted Answer

Acute hepatitis

Answer

Chronic hepatitis

Answer

Acute infection of hepatitis C

Answer

Chronic infection of hepatitis B

Question 4

Lymphocytosis with atypical lymphocytes is seen in infection with which of the following viruses?

Accepted Answer

Epstein-Barr Virus (EBV)

Answer

Herpes Simplex Virus (HSV)

Answer

Hepatitis B Virus (HBV)

Answer

Respiratory Syncytial Virus (RSV)

Question 5

Which of the following viral infections is characterized by the presence of inclusion bodies in neurons?

Accepted Answer

Rabies

Answer

Diphtheria

Answer

Yellow fever

Answer

Japanese encephalitis

Question 6

Which of the following statements about perinatal transmission of HIV is incorrect?

Accepted Answer

Postnatal transmission is not possible.

Answer

It cannot be diagnosed by routine confirmatory tests.

Answer

The infant transmission rate is less than 50%.

Answer

The virus can be isolated from mother's milk.

Question 7

Which virus has a single-stranded RNA genome with segmented genes?

Accepted Answer

Influenza virus

Answer

Rotavirus

Answer

Reovirus

Answer

Measles virus

Question 8

SSPE is a rare complication of which viral infection?

Accepted Answer

Measles

Answer

Mumps

Answer

Rubella

Answer

Influenza

Question 9

Which of the following statements is true regarding chickenpox?

Accepted Answer

The virus is not found in the scabs.

Answer

The virus can be grown on chick embryo.

Answer

It is caused by an RNA virus.

Answer

It does not cross the placental barrier.

Question 10

Which of the following infections is not documented to be spread by sexual contact?

Accepted Answer

Hepatitis E Virus (HEV)

Answer

Hepatitis A Virus (HAV)

Answer

Hepatitis B Virus (HBV)

Answer

Hepatitis C Virus (HCV)

Virology — MCQs

Virology — MCQs

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