Virology Practice Questions

Q: Which antibodies are used to diagnose acute viral hepatitis A and E?

IgM anti-HAV and IgM anti-HEV. **Explanation:** The diagnosis of acute viral hepatitis relies on identifying markers of active infection. In clinical practice, **IgM (Immunoglobulin M)** is the hallmark of an **acute or recent infection**, whereas **IgG (Immunoglobulin G)** typically signifies **past exposure or immunity**. [1] 1. **Why Option A is correct:** Both Hepatitis A (HAV) and Hepatitis E (HEV) are transmitted via the fecal-oral route and cause acute, self-limiting hepatitis. **IgM anti-HAV** is the gold standard for diagnosing acute Hepatitis A [1]; it appears early in the course of the disease and usually becomes undetectable within 3 to 6 months. Similarly, **IgM anti-HEV** is the primary marker for diagnosing acute Hepatitis E. [1] 2. **Why other options are incorrect:** * **Option B:** IgG anti-HAV and IgG anti-HEV indicate past infection or long-term immunity (in the case of HAV, also post-vaccination). They do not differentiate a current acute illness from a previous one. [1] * **Option C:** Liver biopsy is rarely indicated for acute viral hepatitis. It is an invasive procedure reserved for cases of diagnostic uncertainty or chronic liver disease assessment. * **Option D:** While viruses are shed in the stool, this occurs during the late incubation period *before* the onset of clinical symptoms (jaundice). By the time a patient presents to a clinic, stool shedding has often ceased, making it a poor diagnostic tool. **High-Yield Clinical Pearls for NEET-PG:** * **Hepatitis E & Pregnancy:** HEV is notorious for causing **Fulminant Hepatic Failure** in pregnant women (especially in the 3rd trimester), with mortality rates reaching up to 20-25%. * **Hepatitis A:** It is the most common cause of acute viral hepatitis in children worldwide. It never progresses to chronicity. * **Window Period:** In Hepatitis B, the "window period" is diagnosed by **IgM anti-HBc**, as HBsAg and anti-HBs may both be negative.

Q: All the following viruses are transmitted by arthropod vectors except:

Hantavirus. **Explanation:** The core concept tested here is the distinction between **Arboviruses** (Arthropod-borne) and **Roboviruses** (Rodent-borne). **1. Why Hantavirus is the Correct Answer:** Hantavirus belongs to the *Bunyaviridae* family but is a **Robovirus**. It is transmitted to humans via the inhalation of aerosolized excreta (urine, feces, or saliva) from infected **rodents** (e.g., deer mice). It does not require an arthropod vector for transmission. Clinically, it causes two major syndromes: Hantavirus Pulmonary Syndrome (HPS) and Hemorrhagic Fever with Renal Syndrome (HFRS). **2. Why the other options are incorrect:** * **Dengue:** A Flavivirus transmitted by the *Aedes aegypti* mosquito. * **Chikungunya:** A Togavirus (Alphavirus) also transmitted primarily by *Aedes aegypti* and *Aedes albopictus*. * **Japanese Encephalitis (JE):** A Flavivirus transmitted by the *Culex tritaeniorhynchus* mosquito, commonly associated with rice fields. **High-Yield Clinical Pearls for NEET-PG:** * **Arboviruses:** Include members of *Flaviviridae* (Dengue, JE, West Nile, Zika, Yellow Fever), *Togaviridae* (Chikungunya), and *Bunyaviridae* (Crimean-Congo Hemorrhagic Fever). * **Roboviruses:** Include Hantavirus and Arenaviruses (Lassa fever). * **Hantavirus Exception:** While most *Bunyaviridae* are arboviruses, Hantavirus is the notable exception. * **Diagnosis:** Hantavirus is typically diagnosed via IgM ELISA or RT-PCR; remember the "triad" of HFRS: fever, hemorrhage, and acute renal failure.

Q: Pocks on chick embryo are formed by all except?

Chickenpox. ### Explanation The correct answer is **Chickenpox (Varicella-Zoster Virus)**. **1. Why Chickenpox is the correct answer:** The formation of **pocks** (visible necrotic lesions) occurs when certain viruses are inoculated onto the **Chorioallantoic Membrane (CAM)** of a 10–12 day old embryonated chick embryo. This is a classic method for cultivating and identifying members of the **Poxvirus** family. **Chickenpox**, despite its name, is caused by the **Varicella-Zoster Virus (VZV)**, which belongs to the **Herpesvirus** family (*Alphaherpesvirinae*). Herpesviruses do not produce pocks on CAM; VZV, in particular, is highly cell-associated and grows poorly in non-human systems like chick embryos. **2. Analysis of Incorrect Options:** * **Variola (Smallpox):** Produces small, white, convex, non-hemorrhagic pocks. * **Vaccinia:** Produces large, irregular, necrotic pocks with central ulceration. * **Cowpox:** Produces large, **hemorrhagic** (red) pocks. * *Note:* All three belong to the *Orthopoxvirus* genus, which characteristically grow on CAM. **3. High-Yield Clinical Pearls for NEET-PG:** * **Pock Morphology:** * *Variola:* Small, shiny, white pocks. * *Vaccinia:* Large, opaque pocks. * *Cowpox:* Hemorrhagic pocks. * **Temperature Sensitivity:** Variola cannot grow on CAM at temperatures above 38.5°C, whereas Vaccinia can (used to differentiate the two). * **Inclusion Bodies:** * Poxviruses produce **Guarnieri bodies** (intracytoplasmic). * Herpesviruses (like VZV) produce **Cowdry Type A** (intranuclear) inclusions. * **Mnemonic:** "Chickenpox is a Herpes, not a Pox." It does not follow the rules of Poxviruses.

Q: Which strain of influenza causes Swine flu and leads to serious systemic manifestations?

H1N1. **Explanation:** **Correct Option: A (H1N1)** Influenza A virus subtype **H1N1** is the causative agent of **Swine Flu**. The 2009 pandemic strain (A/H1N1pdm09) is a quadruple reassortant virus containing genes from avian, human, and swine influenza viruses. While seasonal flu typically remains localized to the respiratory tract, H1N1 can lead to serious systemic manifestations, including primary viral pneumonia, ARDS, and multi-organ failure. It binds to alpha 2-6 sialic acid receptors (found in the upper respiratory tract) but can also infect the lower respiratory tract, leading to severe cytokine storms. **Incorrect Options:** * **B (H5N1):** This is the highly pathogenic **Avian Influenza** (Bird Flu). While it has a high mortality rate in humans, it does not spread easily from person to person and is not classified as Swine Flu. * **C & D (H3N1/H3N3):** These are less common subtypes. While H3N2 is a major cause of seasonal human influenza, H3N1 and H3N3 are not the primary strains associated with the global Swine Flu outbreaks or systemic pandemics discussed in medical curricula. **High-Yield Clinical Pearls for NEET-PG:** * **Antigenic Shift:** Major genetic changes (reassortment) leading to **Pandemics** (seen in H1N1). * **Antigenic Drift:** Minor point mutations leading to **Epidemics**. * **Drug of Choice:** **Oseltamivir** (Neuraminidase inhibitor), effective against both Influenza A and B. * **Diagnosis:** Real-time RT-PCR is the gold standard. * **Hemagglutinin (H):** Responsible for cell attachment; **Neuraminidase (N):** Responsible for the release of new virions.

Q: Which of the following diseases is NOT associated with Epstein-Barr virus infection?

Epidermodysplasia verruciformis. **Explanation:** The correct answer is **B. Epidermodysplasia verruciformis**. **Epidermodysplasia verruciformis (EV)**, also known as "tree man syndrome," is a rare autosomal recessive genetic hereditary skin disorder associated with a high risk of skin cancer. It is caused by an abnormal susceptibility to specific types of **Human Papillomavirus (HPV)**, most commonly types 5 and 8, rather than the Epstein-Barr virus (EBV). **Why the other options are incorrect:** * **Infectious Mononucleosis (Option A):** This is the classic primary infection caused by EBV (Glandular fever). It is characterized by the triad of fever, pharyngitis, and lymphadenopathy, with the presence of atypical lymphocytes (Downey cells) on a peripheral smear. * **Nasopharyngeal Carcinoma (Option C):** EBV is strongly oncogenic and is a major etiological factor for nasopharyngeal carcinoma, particularly the undifferentiated type (Type III), common in Southern China and Southeast Asia. * **Oral Hairy Leukoplakia (Option D):** This is a white, non-scrapable plaque on the lateral borders of the tongue, seen almost exclusively in HIV-positive or immunocompromised patients. It is caused by the opportunistic replication of EBV in the oral epithelium. **High-Yield Clinical Pearls for NEET-PG:** * **EBV Receptor:** It binds to the **CD21** receptor (CR2) on B-cells. * **Diagnosis:** The **Paul-Bunnell Test** (Heterophile antibody test) is the classic screening test for Infectious Mononucleosis. * **Other EBV Associations:** Burkitt Lymphoma (starry-sky appearance), Hodgkin Lymphoma (Mixed cellularity type), and Gastric Carcinoma. * **EV Association:** Remember that EV is linked to **HPV-5 and HPV-8**, which are considered "high-risk" in the context of this specific genetic predisposition.

Q: Which of the following is false regarding the transmission of Rubella?

Infection in early pregnancy causes milder disease. ### Explanation The correct answer is **C (Infection in early pregnancy causes milder disease)** because this statement is factually incorrect. In Rubella, the severity of fetal damage is **inversely proportional** to the gestational age at the time of infection. 1. **Why Option C is False:** Infection during the **first trimester** (especially the first 8–12 weeks) is the most critical period. During this stage of organogenesis, the virus causes chronic fetal infection leading to cell death and inhibited mitosis, resulting in severe Congenital Rubella Syndrome (CRS) or spontaneous abortion. 2. **Why Option A is Correct:** Rubella is primarily transmitted via **respiratory droplets** from the nasopharyngeal secretions of infected individuals. 3. **Why Option B is Correct:** **Vertical transmission** (transplacental) is the hallmark of Rubella, where the virus crosses the placenta to infect the fetus during maternal viremia. 4. **Why Option D is Correct:** As gestational age increases, the risk of multi-organ defects decreases. If infection occurs after the 16th week (late pregnancy), the risk of major malformations is low, but **sensorineural hearing loss** may occur as an isolated finding. --- ### High-Yield Clinical Pearls for NEET-PG * **Gregg’s Triad (Classic CRS):** 1. Cataract (Salt & Pepper Retinopathy), 2. Cardiac defects (Patent Ductus Arteriosus is most common), 3. Sensorineural Deafness. * **Blueberry Muffin Rash:** Seen in neonates due to extramedullary hematopoiesis. * **Diagnosis:** IgM antibodies in the neonate or persistence of IgG beyond 6 months (since maternal IgG should normally wane). * **Vaccine:** Live attenuated **RA 27/3 strain** (grown in human diploid cells). It is contraindicated in pregnancy; pregnancy should be avoided for 1 month post-vaccination.

Q: Epidemic conjunctivitis is reported in a rural area. What is the most probable causative organism?

Adenovirus. **Explanation:** **Adenovirus** is the most common cause of viral conjunctivitis worldwide and is the primary agent responsible for outbreaks of **Epidemic Keratoconjunctivitis (EKC)**. It is highly contagious, often spreading through respiratory droplets, contaminated fingers, or ophthalmic instruments (like tonometers). EKC is typically caused by **Adenovirus serotypes 8, 19, and 37**. It presents with sudden onset follicular conjunctivitis, preauricular lymphadenopathy, and characteristic subepithelial corneal infiltrates. **Why other options are incorrect:** * **Herpes Simplex Virus (HSV):** Usually causes unilateral blepharoconjunctivitis or keratitis (dendritic ulcers) rather than large-scale epidemics. * **Epstein-Barr Virus (EBV):** While it can cause follicular conjunctivitis or Parinaud’s oculoglandular syndrome, it is a rare cause and does not present as an epidemic. * **Papilloma Virus:** Primarily causes benign conjunctival papillomas (warts) rather than acute infectious conjunctivitis. **High-Yield Clinical Pearls for NEET-PG:** 1. **Pharyngoconjunctival Fever (PCF):** Also caused by Adenovirus (serotypes 3, 4, 7). It presents as a triad of fever, pharyngitis, and follicular conjunctivitis (often seen in children/swimming pools). 2. **Transmission:** The virus can survive on dry surfaces for weeks; strict hand hygiene is the most important preventive measure. 3. **Hemorrhagic Conjunctivitis:** If the question mentions "Acute Hemorrhagic Conjunctivitis" (AHC) in an epidemic, consider **Enterovirus 70** or **Coxsackievirus A24**. 4. **Treatment:** Primarily supportive (cold compresses, artificial tears). Topical steroids are reserved for severe subepithelial infiltrates affecting vision.

Q: Which of the following cancers is NOT associated with Human Papilloma virus?

Testicular cancer. **Explanation:** Human Papillomavirus (HPV) is a small, double-stranded DNA virus with a strong tropism for **squamous epithelial cells**. It integrates its DNA into the host genome, leading to the overexpression of oncoproteins **E6 and E7**, which inhibit tumor suppressor proteins **p53 and pRb**, respectively. This process drives malignant transformation in specific anatomical sites. **Why Testicular Cancer is the Correct Answer:** Testicular cancer (most commonly Germ Cell Tumors like Seminomas) is primarily associated with genetic factors, cryptorchidism, and Klinefelter syndrome. It is **not** caused by viral integration or HPV infection. The epithelium of the testes is not a target for HPV-mediated oncogenesis. **Why the other options are incorrect:** * **Cervical Cancer:** HPV is the primary etiological agent in >99% of cases, particularly high-risk strains **16 and 18**. * **Vulval Cancer:** A significant proportion of vulvar squamous cell carcinomas (especially the basaloid and warty types) are HPV-related. * **Oropharyngeal Cancer:** There is a rising incidence of HPV-associated squamous cell carcinoma of the oropharynx (specifically the tonsils and base of tongue), often linked to HPV-16. **High-Yield Clinical Pearls for NEET-PG:** * **High-risk HPV types:** 16, 18 (most common), 31, 33, 45. * **Low-risk HPV types:** 6, 11 (cause Genital Warts/Condyloma Acuminata). * **Other HPV-associated cancers:** Anal cancer and Penile cancer. * **Vaccination:** The Quadrivalent vaccine (Gardasil) targets types 6, 11, 16, and 18. * **Screening:** HPV DNA testing is now preferred over or used in conjunction with Pap smears for cervical cancer screening.

Q: Intracytoplasmic inclusion bodies are characteristic of which viral infection?

Rabies Virus. **Explanation:** The correct answer is **Rabies Virus**. Inclusion bodies are aggregates of viral proteins or particles within a cell that serve as diagnostic hallmarks. **1. Why Rabies Virus is Correct:** Rabies virus (a Rhabdovirus) is characterized by the presence of **Negri bodies**. These are pathognomonic, eosinophilic, **intracytoplasmic** inclusion bodies found most commonly in the Purkinje cells of the cerebellum and the pyramidal cells of the hippocampus. They represent sites of viral replication (ribonucleoprotein accumulation). **2. Analysis of Incorrect Options:** * **Herpes Simplex Virus (HSV):** Characterized by **Cowdry Type A** inclusion bodies, which are **intranuclear** (not intracytoplasmic) and eosinophilic, often surrounded by a clear halo. * **Poliovirus:** While it replicates in the cytoplasm, it does not typically produce distinct, diagnostic inclusion bodies used for identification in clinical pathology. * **Yellow Fever Virus:** Characterized by **Councilman bodies**, which are eosinophilic globules resulting from the apoptosis of hepatocytes. While found in the cytoplasm, they are technically remnants of degenerate hepatocytes rather than classic viral replication inclusions. **3. High-Yield Clinical Pearls for NEET-PG:** * **Intranuclear Inclusions:** HSV (Cowdry A), CMV (Owl’s eye), Adenovirus (Smudge cells). * **Intracytoplasmic Inclusions:** Rabies (Negri bodies), Poxvirus (Guarnieri bodies), Molluscum contagiosum (Henderson-Patterson bodies). * **Both Intranuclear & Intracytoplasmic:** Measles (Warthin-Finkeldey cells/Inclusions). * **Rabies Diagnosis:** While Negri bodies are specific, the gold standard for diagnosis is the Direct Fluorescent Antibody (DFA) test.

Question 1

Human rotaviruses are characterized by which of the following statements?

Accepted Answer

They can be sensitively and rapidly detected in stools by the enzyme-linked immunosorbent assay (ELISA) technique

Answer

They produce an infection that is primarily seen in adults

Answer

They produce cytopathic effects in many conventional tissue culture systems

Answer

They are lipid-containing RNA viruses possessing a double-shelled capsid

Question 2

Which antibodies are used to diagnose acute viral hepatitis A and E?

Accepted Answer

IgM anti-HAV and IgM anti-HEV

Answer

IgG anti-HAV and IgG anti-HEV

Answer

Liver biopsy

Answer

Virus detection in stool

Question 3

All the following viruses are transmitted by arthropod vectors except:

Accepted Answer

Hantavirus

Answer

Dengue

Answer

Chikungunya

Answer

Japanese Encephalitis

Question 4

Pocks on chick embryo are formed by all except?

Accepted Answer

Chickenpox

Answer

Variola

Answer

Vaccinia

Answer

Cowpox

Question 5

Which strain of influenza causes Swine flu and leads to serious systemic manifestations?

Accepted Answer

H1N1

Answer

H5N1

Answer

H3N1

Answer

H3N3

Question 6

Which of the following diseases is NOT associated with Epstein-Barr virus infection?

Accepted Answer

Epidermodysplasia verruciformis

Answer

Infectious mononucleosis

Answer

Nasopharyngeal carcinoma

Answer

Oral Hairy leukoplakia

Question 7

Which of the following is false regarding the transmission of Rubella?

Accepted Answer

Infection in early pregnancy causes milder disease

Answer

Droplet infection

Answer

Vertical transmission

Answer

Fetus affected in late pregnancy may have only deafness

Question 8

Epidemic conjunctivitis is reported in a rural area. What is the most probable causative organism?

Accepted Answer

Adenovirus

Answer

Herpes virus

Answer

EB virus

Answer

Papilloma virus

Question 9

Which of the following cancers is NOT associated with Human Papilloma virus?

Accepted Answer

Testicular cancer

Answer

Cervical cancer

Answer

Vulval cancer

Answer

Oropharyngeal cancer

Question 10

Intracytoplasmic inclusion bodies are characteristic of which viral infection?

Accepted Answer

Rabies Virus

Answer

Herpes Simplex Virus (HSV)

Answer

Poliovirus

Answer

Yellow Fever Virus

Virology — MCQs

Virology — MCQs

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