Virology Practice Questions

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.

Q: What types of human papillomavirus are most commonly associated with cervical carcinoma?

Types 16, 18, 31. **Explanation:** Cervical carcinoma is primarily caused by persistent infection with **High-Risk Human Papillomavirus (HR-HPV)**. These viruses integrate their DNA into the host genome, leading to the overexpression of oncoproteins **E6 and E7**, which inactivate tumor suppressor proteins **p53 and pRb**, respectively. * **Why Option B is Correct:** HPV types **16 and 18** are the most oncogenic, accounting for approximately 70% of all cervical cancers worldwide (HPV 16 is associated with Squamous Cell Carcinoma, while HPV 18 is strongly linked to Adenocarcinoma). Type **31** is the next most common high-risk subtype. Other high-risk types include 33, 35, 45, 52, and 58. * **Why Options A, C, and D are Incorrect:** * **Types 6 and 11** (found in Options A and C) are **Low-Risk HPV** types. They are responsible for 90% of genital warts (Condyloma acuminata) and recurrent respiratory papillomatosis but rarely cause malignancy. * Types such as 3, 8, 10, and 12 are generally associated with cutaneous warts or other non-cervical conditions and do not have a significant association with cervical neoplasia. **High-Yield Clinical Pearls for NEET-PG:** * **Most common type:** HPV 16 (found in ~50-60% of cases). * **Screening:** The primary screening tool is the Pap smear (cytology) or HPV DNA testing (COBAS). * **Vaccination:** The **Nonavalent vaccine (Gardasil 9)** covers types 6, 11, 16, 18, 31, 33, 45, 52, and 58. * **Transformation Zone:** The most common site for cervical cancer development is the Squamocolumnar Junction (SCJ).

Q: Which of the following viruses is primarily transmitted by the fecal-oral route?

Coxsackievirus. **Explanation:** The correct answer is **Coxsackievirus**. **1. Why Coxsackievirus is correct:** Coxsackieviruses belong to the **Picornaviridae** family under the genus **Enterovirus**. As the name suggests, enteroviruses are primarily inhabitants of the enteric tract. They are acid-stable, allowing them to survive the gastric pH, and are transmitted predominantly via the **fecal-oral route**. They replicate in the Peyer’s patches of the intestine before spreading hematogenously to target organs (skin, heart, meninges). **2. Why the other options are incorrect:** * **St. Louis encephalitis virus (Option A):** This is a Flavivirus transmitted by the bite of infected **Culex mosquitoes**. * **Colorado tick fever virus (Option B):** This is a Reovirus (Coltivirus) transmitted by the bite of the **Dermacentor andersoni (wood tick)**. * **Yellow fever virus (Option D):** This is a Flavivirus transmitted by the **Aedes aegypti mosquito**. **3. NEET-PG High-Yield Pearls:** * **Coxsackie A:** Classically associated with **Herpangina** and **Hand-Foot-and-Mouth Disease (HFMD)**. * **Coxsackie B:** The most common viral cause of **Myocarditis** and **Pericarditis**; also causes Pleurodynia (Bornholm disease/Devil’s grip). * **Enteroviruses (General):** They are the leading cause of **Aseptic Meningitis**. * **Rule of Thumb:** Most "Arboviruses" (Arthropod-borne) are transmitted by mosquitoes or ticks, whereas "Enteroviruses" are transmitted via the fecal-oral route.

Q: Parvovirus B-19 does not cause which of the following conditions?

Roseola infantum. **Explanation:** **Parvovirus B19** is a small, single-stranded DNA virus that targets erythroid progenitor cells by binding to the **P-antigen** (globoside). **Why Roseola Infantum is the correct answer:** Roseola infantum (also known as Exanthema Subitum or Sixth Disease) is caused by **Human Herpesvirus 6 (HHV-6)**, and occasionally HHV-7. It is characterized by high fever for 3–5 days, followed by the sudden appearance of a maculopapular rash as the fever subsides. Parvovirus B19, conversely, causes **Erythema Infectiosum (Fifth Disease)**, famous for the "slapped-cheek" appearance. **Analysis of other options:** * **Aplastic Anemia:** Parvovirus B19 infects and lyses red blood cell precursors. In patients with high RBC turnover (e.g., **Sickle Cell Disease**, Hereditary Spherocytosis), this leads to a life-threatening **Transient Aplastic Crisis**. * **Fetal Hydrops:** If a pregnant woman is infected, the virus crosses the placenta, attacks fetal erythroid cells, and causes severe anemia. This leads to high-output cardiac failure, generalized edema (**Hydrops Fetalis**), and potential fetal death. * **Collapsing FSGS:** While HIV is the most common viral cause, Parvovirus B19 is a well-documented trigger for the **collapsing variant of Focal Segmental Glomerulosclerosis**, particularly in immunocompromised patients. **High-Yield Clinical Pearls for NEET-PG:** * **Receptor:** P-antigen (found on RBCs, megakaryocytes, and endothelial cells). * **Arthropathy:** In adults (especially females), B19 often presents as symmetrical small joint arthritis resembling RA. * **Pure Red Cell Aplasia (PRCA):** Occurs in immunocompromised individuals due to chronic B19 infection. * **Diagnosis:** IgM antibodies (acute) or PCR (in immunocompromised/aplastic crisis).

Question 1

Pocks on chick embryo are formed by all except?

Accepted Answer

Chickenpox

Answer

Variola

Answer

Vaccinia

Answer

Cowpox

Question 2

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

Accepted Answer

H1N1

Answer

H5N1

Answer

H3N1

Answer

H3N3

Question 3

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 4

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 5

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 6

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 7

Intracytoplasmic inclusion bodies are characteristic of which viral infection?

Accepted Answer

Rabies Virus

Answer

Herpes Simplex Virus (HSV)

Answer

Poliovirus

Answer

Yellow Fever Virus

Question 8

What types of human papillomavirus are most commonly associated with cervical carcinoma?

Accepted Answer

Types 16, 18, 31

Answer

Types 6, 12, 18

Answer

Types 6, 8, 11

Answer

Types 3, 10, 19

Question 9

Which of the following viruses is primarily transmitted by the fecal-oral route?

Accepted Answer

Coxsackievirus

Answer

St. Louis encephalitis virus

Answer

Colorado tick fever virus

Answer

Yellow fever virus

Question 10

Parvovirus B-19 does not cause which of the following conditions?

Accepted Answer

Roseola infantum

Answer

Aplastic anemia in sickle cell disease

Answer

Fetal hydrops

Answer

Collapsing focal segmental glomerulosclerosis

Virology — MCQs

Virology — MCQs

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