Virology Practice Questions

Q: Which of the following is NOT true about Rotavirus?

Rota B can be grown in cell culture. **Explanation:** Rotavirus is the most common cause of severe diarrhea in infants and young children worldwide. Understanding its classification and cultivation is crucial for NEET-PG. **Why Option B is the Correct Answer (The False Statement):** Rotaviruses are notoriously difficult to grow in standard cell cultures. While **Group A Rotavirus** can be grown in specialized cell lines (like MA104) with the addition of proteolytic enzymes (trypsin) to enhance infectivity, **Group B and Group C Rotaviruses cannot be grown in cell culture.** Therefore, the statement that "Rota B can be grown in cell culture" is incorrect. **Analysis of Other Options:** * **Option A:** Rotaviruses are the leading cause of viral gastroenteritis in both humans and children, typically presenting with vomiting followed by watery diarrhea. * **Option C:** Rotavirus is classified into groups A through G. While Group A is the most common, **Group C** is a recognized cause of sporadic cases and outbreaks of diarrhea in children. * **Option D:** In routine clinical practice, culture is not performed because it is difficult, slow, and lacks sensitivity. Diagnosis is instead made via **ELISA** or **Latex Agglutination** for antigen detection in stool. **High-Yield Clinical Pearls for NEET-PG:** * **Morphology:** Wheel-like appearance (*Rota* = wheel) under electron microscopy due to its double-shelled capsid. * **Genome:** Segmented, double-stranded RNA (11 segments). * **Pathogenesis:** Produces an enterotoxin called **NSP4**, which induces secretory diarrhea. * **Vaccines:** Live attenuated oral vaccines (Rotarix, RotaTeq, and Rotavac) are part of the Universal Immunization Programme (UIP).

Q: Nipah virus is associated with epidemics of which condition?

Encephalitis. **Explanation:** Nipah virus (NiV) is a highly pathogenic zoonotic virus belonging to the genus **Henipavirus** (Family: Paramyxoviridae). The primary clinical manifestation of Nipah virus infection in humans is **acute encephalitis**, characterized by fever, headache, and altered consciousness, often progressing rapidly to coma and death. **Why Encephalitis is the correct answer:** The virus exhibits strong neurotropism. It enters the central nervous system via the olfactory nerve and through hematogenous spread, causing widespread vasculitis, endothelial damage, and parenchymal inflammation. This leads to severe cerebral edema and neurological deterioration, with a high case fatality rate (40% to 75%). **Analysis of other options:** * **Hepatitis:** While systemic involvement can occur, Nipah virus is not a primary hepatotropic virus. Hepatitis is not a defining clinical feature of the epidemics. * **Pneumonia:** Although Nipah virus can cause severe respiratory illness (Acute Respiratory Distress Syndrome), especially noted in the Malaysian and Singaporean outbreaks, **Encephalitis** remains the hallmark and most common cause of mortality in major epidemics (such as those in India and Bangladesh). * **All of the above:** While respiratory symptoms exist, the primary association and the "classic" board-exam presentation for Nipah is Encephalitis. **High-Yield Clinical Pearls for NEET-PG:** * **Natural Reservoir:** Fruit bats (Pteropus species). * **Transmission:** Consumption of raw date palm sap contaminated by bat saliva/urine, or direct contact with infected pigs (intermediate hosts). * **Diagnosis:** RT-PCR (gold standard) or ELISA for IgM/IgG antibodies. * **Histopathology:** Characteristic **syncytia formation** (multinucleated giant cells) in vascular endothelium. * **Recent Context:** Frequent outbreaks in Kerala, India, make this a high-priority topic.

Q: What is the most sensitive diagnostic test for dengue?

Reverse transcriptase PCR. **Explanation:** The correct answer is **Reverse transcriptase PCR (RT-PCR)**. **1. Why RT-PCR is the correct answer:** RT-PCR is the most sensitive and specific diagnostic tool for Dengue virus (DENV) because it directly detects the viral RNA. It is highly effective during the **viremic phase** (typically the first 5 days of illness), even before antibodies or the NS1 antigen become detectable. Its ability to amplify even minute quantities of genetic material makes it the gold standard for early diagnosis and serotype identification. **2. Why the other options are incorrect:** * **IgM ELISA:** This is a serological test used for "probable" diagnosis. It only becomes positive after the 5th day of fever (post-viremic phase). While widely used, it is less sensitive than RT-PCR in the early stages and can show cross-reactivity with other flaviviruses (like Zika or Japanese Encephalitis). * **Complement Fixation Test (CFT):** This is an older serological method with low sensitivity and high cross-reactivity. It is rarely used in modern clinical practice for Dengue. * **Electron Microscopy:** While it can visualize viral particles, it is extremely labor-intensive, expensive, and has very low sensitivity for routine clinical diagnosis. **Clinical Pearls for NEET-PG:** * **Early Diagnosis (Day 1–5):** RT-PCR (Most sensitive) and **NS1 Antigen** (Most common bedside/screening test). * **Late Diagnosis (>Day 5):** IgM ELISA (MAC-ELISA). * **Gold Standard for Serotyping:** RT-PCR. * **Confirmatory Test (Reference):** Plaque Reduction Neutralization Test (PRNT). * **Hematological Hallmark:** Thrombocytopenia (low platelets) and rising Hematocrit (due to capillary leak).

Q: Which is the most common opportunistic retinal infection associated with HIV?

CMV retinitis. **Explanation:** **CMV retinitis** is the most common opportunistic ocular infection and the leading cause of blindness in patients with advanced HIV/AIDS. It typically occurs when the **CD4+ T-cell count falls below 50 cells/mm³**. The pathogenesis involves the reactivation of latent Cytomegalovirus, leading to full-thickness retinal necrosis and edema. Clinically, it presents as painless vision loss, floaters, or "flashing lights." On fundoscopy, it is characterized by the classic **"Pizza-pie appearance"** or **"Cottage cheese and ketchup appearance"** (hemorrhage mixed with white fluffy exudates). **Analysis of Incorrect Options:** * **VZV (Varicella-Zoster Virus):** Causes Acute Retinal Necrosis (ARN) or Progressive Outer Retinal Necrosis (PORN). While aggressive, it is significantly less common than CMV in HIV patients. * **Syphilitic retinitis:** Known as the "Great Imitator," it can occur at any CD4 count. While rising in prevalence among HIV-positive individuals, it is not the *most common* opportunistic retinal infection. * **Herpes simplex (HSV):** Can cause Acute Retinal Necrosis (ARN), typically presenting with rapid, painful vision loss, but it is a rare cause of retinitis compared to CMV. **High-Yield Pearls for NEET-PG:** * **Drug of Choice:** Oral Valganciclovir (or IV Ganciclovir). Foscarnet is used in ganciclovir-resistant cases. * **Diagnosis:** Primarily clinical via dilated fundoscopy; PCR of aqueous or vitreous humor can be used for confirmation. * **Complication:** Retinal detachment is a frequent and serious complication of CMV retinitis. * **Immune Recovery Uveitis (IRU):** An inflammatory reaction that can occur after starting ART as the immune system recovers.

Q: Which of the following is a member of the family Herpesviridae, characterized as an enveloped virus with an icosahedral nucleocapsid containing a double-stranded linear DNA genome?

Cytomegalovirus (CMV). **Explanation:** The question describes the classic structural characteristics of the **Herpesviridae** family. Members of this family are characterized by a **large, enveloped** virion, an **icosahedral nucleocapsid**, and a **linear double-stranded DNA (dsDNA)** genome. Between the capsid and the envelope lies a proteinaceous layer called the **tegument**. **1. Why Cytomegalovirus (CMV) is correct:** CMV (Human Herpesvirus 5) belongs to the Betaherpesvirinae subfamily. It perfectly fits the description: it is enveloped, possesses an icosahedral capsid, and contains linear dsDNA. It is a major cause of congenital infections and opportunistic infections in immunocompromised patients (e.g., transplant recipients, HIV). **2. Why the other options are incorrect:** * **Poliovirus:** A member of the *Picornaviridae* family. It is **non-enveloped** (naked) and contains a **ssRNA** genome. * **Human Papillomavirus (HPV):** A member of the *Papillomaviridae* family. While it has an icosahedral capsid and dsDNA, it is **non-enveloped** and its DNA is **circular**, not linear. * **Influenza virus:** A member of the *Orthomyxoviridae* family. It is enveloped but has a **helical** nucleocapsid and a **segmented ssRNA** genome. **Clinical Pearls for NEET-PG:** * **CMV Histology:** Look for "Owl’s eye" intranuclear inclusion bodies. * **Latency:** All Herpesviruses establish lifelong latency (CMV remains latent in mononuclear cells/lymphocytes). * **Site of Replication:** Unlike most RNA viruses, all DNA viruses (except Poxvirus) replicate in the **nucleus**. * **Envelope Origin:** Herpesviruses acquire their envelope by budding through the **inner nuclear membrane**.

Q: Which of the following conditions is NOT caused by Enterovirus (formerly Echovirus)?

Hemorrhagic conjunctivitis. **Explanation:** The question asks which condition is **NOT** caused by **Echoviruses** (a sub-genus of Enteroviruses). **1. Why "Hemorrhagic Conjunctivitis" is the correct answer:** While Echoviruses cause a wide spectrum of diseases, **Acute Hemorrhagic Conjunctivitis (AHC)** is specifically and classically caused by **Enterovirus 70** and **Coxsackievirus A24**. While these belong to the same *Enterovirus* genus, they are distinct from the Echovirus group. AHC is characterized by sudden onset of subconjunctival hemorrhage, pain, and lid edema. **2. Analysis of Incorrect Options (Conditions caused by Echoviruses):** * **Herpangina:** Primarily caused by Coxsackievirus A, but **Echoviruses** are also known causative agents. It presents with painful vesicles and ulcers on the posterior pharynx and soft palate. * **Pleurodynia (Bornholm disease):** Classically associated with Coxsackievirus B, but **Echoviruses** can also cause this paroxysmal, sharp chest pain due to intercostal muscle involvement. * **Myocarditis:** Along with Coxsackievirus B (the most common cause), **Echoviruses** are significant viral triggers for inflammatory cardiomyopathy and pericarditis. **3. NEET-PG High-Yield Pearls:** * **Echovirus** stands for *Enteric Cytopathic Human Orphan* virus. * **Aseptic Meningitis:** Echoviruses (especially types 6, 9, 11, and 30) are the **most common cause** of viral meningitis. * **Hand-Foot-Mouth Disease (HFMD):** Primarily caused by Coxsackievirus A16 and Enterovirus 71. * **Rule of Thumb:** If a question asks for the most common cause of non-polio enteroviral disease, Echoviruses are often the answer. However, for specific "hemorrhagic" eye infections, think **EV-70**.

Q: Which of the following viruses possesses a lipid envelope?

Herpesvirus. **Explanation:** The presence or absence of a lipid envelope is a fundamental classification feature in virology. Enveloped viruses acquire their lipid bilayer from host cell membranes (plasma, nuclear, or ER membranes) during the budding process. **1. Why Herpesvirus is Correct:** Herpesviruses (e.g., HSV, VZV, CMV, EBV) are large, **enveloped**, double-stranded DNA viruses. Uniquely, they acquire their envelope by budding through the **inner nuclear membrane** of the host cell. The envelope contains viral glycoproteins essential for attachment and entry into host cells. **2. Why the other options are incorrect:** * **Reovirus (Option A):** These are non-enveloped, double-stranded RNA viruses. They possess a unique double-layered icosahedral capsid which makes them resistant to detergents and acidic environments (like the GI tract). * **Picornavirus (Option B):** This family (including Poliovirus, Rhinovirus, and Hepatitis A) consists of small, non-enveloped, positive-sense single-stranded RNA viruses. **High-Yield Clinical Pearls for NEET-PG:** * **Mnemonic for DNA Viruses:** "HHAPPPPy" (Herpes, Hepadna, Adeno, Papilloma, Polyoma, Pox, Parvo). * **Enveloped DNA:** Herpes, Hepadna, Pox. * **Non-enveloped DNA:** Adeno, Papilloma, Polyoma, Parvo. * **Sensitivity:** Enveloped viruses are generally more fragile; they are easily inactivated by heat, detergents, and lipid solvents (like ether or alcohol). Non-enveloped (naked) viruses are typically more stable in the environment and are often transmitted via the feco-oral route. * **Exception:** Poxvirus is the only DNA virus that replicates in the cytoplasm and carries its own DNA-dependent RNA polymerase.

Q: Inclusion bodies of vaccinia are known as?

Guarnieri bodies. **Explanation:** **Guarnieri bodies** are the characteristic intracytoplasmic inclusion bodies seen in cells infected with the **Vaccinia virus** (the virus used in the smallpox vaccine) and the Variola virus (Smallpox). Since Poxviruses are unique among DNA viruses because they replicate entirely within the **cytoplasm**, these inclusions represent "viral factories" where viral replication and assembly occur. They appear as eosinophilic (pinkish) masses on H&E staining. **Analysis of Incorrect Options:** * **Negri bodies:** These are pathognomonic intracytoplasmic eosinophilic inclusions found in pyramidal cells of the hippocampus and Purkinje cells of the cerebellum in **Rabies**. * **Asteroid bodies:** These are star-shaped eosinophilic inclusions found within giant cells in granulomatous conditions, most classically **Sarcoidosis** and Sporotrichosis. * **Schuffner dots:** These are fine stippling (morphological changes) seen in red blood cells infected with **Plasmodium vivax** and *Plasmodium ovale* malaria. **High-Yield Clinical Pearls for NEET-PG:** * **Poxvirus Rule:** Most DNA viruses replicate in the nucleus and produce intranuclear inclusions (e.g., Herpes - Cowdry Type A). Poxviruses are the **exception**; they replicate in the cytoplasm and produce **intracytoplasmic** inclusions (Guarnieri bodies). * **Molluscum Contagiosum:** Another Poxvirus that produces large, eosinophilic intracytoplasmic inclusions known as **Henderson-Patterson bodies**. * **Cowdry Type A:** Seen in HSV and VZV (Lipshutz bodies). * **Owl’s Eye Appearance:** Characteristic intranuclear inclusion of **CMV**.

Q: Warthin Finkeldey giant cells are characteristic of which viral infection?

Measles. **Explanation:** **Warthin-Finkeldey giant cells** are the pathognomonic histopathological hallmark of **Measles (Rubeola)**. These are large, multinucleated giant cells formed by the fusion of infected lymphocytes, macrophages, or epithelial cells (syncytia formation). They typically contain eosinophilic inclusion bodies in both the **cytoplasm and the nucleus** (Cowdry type A inclusions). These cells are most commonly found in lymphoid tissues such as the tonsils, lymph nodes, and appendix during the prodromal stage of the disease. **Analysis of Options:** * **Option A (CMV):** Characterized by "Owl’s eye" appearance, which refers to large intranuclear inclusions surrounded by a clear halo. It does not produce Warthin-Finkeldey cells. * **Option B (NIHL):** This is a non-infectious condition related to auditory trauma; it has no viral or histopathological association with giant cells. * **Option D (Giant cell tumour):** While this involves giant cells (osteoclast-like), they are neoplastic/reactive in nature and lack the specific viral inclusions and lymphoid distribution characteristic of Measles. **High-Yield Clinical Pearls for NEET-PG:** * **Koplik Spots:** The clinical pathognomonic sign of Measles (found on buccal mucosa opposite the lower 2nd molars). * **Vitamin A:** Supplementation is crucial in Measles management to reduce morbidity and mortality. * **SSPE (Subacute Sclerosing Panencephalitis):** A late, fatal neurological complication caused by a defective measles virus. * **Rule of 3 C’s:** Prodromal symptoms include Cough, Coryza, and Conjunctivitis.

Q: What is the first antibody to appear in plasma during acute hepatitis B infection?

IgM Anti-HBc. ### Explanation In the serological course of an acute Hepatitis B Virus (HBV) infection, **IgM Anti-HBc** (Immunoglobulin M antibody to Hepatitis B core antigen) is the first **antibody** to appear in the plasma. #### Why IgM Anti-HBc is Correct: While **HBsAg** is the first *marker* (antigen) to appear in the blood, **IgM Anti-HBc** is the first *antibody* produced by the immune system. It typically appears shortly after HBsAg, often before the onset of clinical symptoms. Crucially, it is the only marker present during the **"Window Period"**—the interval when HBsAg has disappeared but Anti-HBs has not yet become detectable. #### Why Other Options are Incorrect: * **Anti-HBs:** This antibody appears only after the resolution of the infection or following vaccination. Its presence indicates immunity and clinical recovery. * **Anti-HBe:** This antibody appears after the disappearance of the HBeAg (envelope antigen). It signifies a transition from high viral replication to a low-replicative state; it is not the initial antibody response. * **IgG Anti-HBc (Distinction):** While not an option here, it is important to note that IgG Anti-HBc replaces IgM over time and persists for life, indicating a past exposure rather than an acute phase. #### High-Yield Clinical Pearls for NEET-PG: * **Window Period Marker:** IgM Anti-HBc is the diagnostic marker of choice for acute HBV during the window period. * **HBsAg:** First marker to appear overall (Antigen). * **HBeAg:** Indicator of high infectivity and active viral replication. * **Vaccination Profile:** A vaccinated individual will be **Anti-HBs positive** but **Anti-HBc negative** (since the vaccine contains only the surface antigen). * **Natural Infection Profile:** A person recovered from natural infection will be positive for **both** Anti-HBs and Anti-HBc (IgG).

Question 1

Which of the following is NOT true about Rotavirus?

Accepted Answer

Rota B can be grown in cell culture

Answer

Causes diarrhea in man and children

Answer

Rota C can cause diarrhea in children

Answer

Culture cannot be done

Question 2

Nipah virus is associated with epidemics of which condition?

Accepted Answer

Encephalitis

Answer

Hepatitis

Answer

Pneumonia

Answer

All of the above

Question 3

What is the most sensitive diagnostic test for dengue?

Accepted Answer

Reverse transcriptase PCR

Answer

IgM ELISA

Answer

Complement fixation test

Answer

Electron microscopy

Question 4

Which is the most common opportunistic retinal infection associated with HIV?

Accepted Answer

CMV retinitis

Answer

VZV

Answer

Syphilitic retinitis

Answer

Herpes simplex

Question 5

Which of the following is a member of the family Herpesviridae, characterized as an enveloped virus with an icosahedral nucleocapsid containing a double-stranded linear DNA genome?

Accepted Answer

Cytomegalovirus (CMV)

Answer

Poliovirus

Answer

Human Papillomavirus (HPV)

Answer

Influenza virus

Question 6

Which of the following conditions is NOT caused by Enterovirus (formerly Echovirus)?

Accepted Answer

Hemorrhagic conjunctivitis

Answer

Herpangina

Answer

Pleurodynia

Answer

Myocarditis

Question 7

Which of the following viruses possesses a lipid envelope?

Accepted Answer

Herpesvirus

Answer

Reovirus

Answer

Picornavirus

Answer

All of the above

Question 8

Inclusion bodies of vaccinia are known as?

Accepted Answer

Guarnieri bodies

Answer

Negri bodies

Answer

Asteroid bodies

Answer

Schuffner dots

Question 9

Warthin Finkeldey giant cells are characteristic of which viral infection?

Accepted Answer

Measles

Answer

Cytomegalovirus (CMV)

Answer

Noise-induced hearing loss (NIHL)

Answer

Giant cell tumour of tendon sheath

Question 10

What is the first antibody to appear in plasma during acute hepatitis B infection?

Accepted Answer

IgM Anti-HBc

Answer

Anti-HBs

Answer

Anti-HBe

Virology — MCQs

Virology — MCQs

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