Virology Practice Questions

Q: What is the oropharyngeal manifestation of HIV infection?

Oral hairy leukoplakia. **Explanation:** **Oral Hairy Leukoplakia (OHL)** is a classic opportunistic manifestation of HIV infection. It is caused by the reactivation of the **Epstein-Barr Virus (EBV)** in the setting of profound immunosuppression (typically when CD4 counts fall below 200-300 cells/mm³). Clinically, it presents as white, corrugated (ribbed), non-scrapable patches, most commonly found on the **lateral borders of the tongue**. Unlike oral candidiasis, these lesions cannot be rubbed off. **Analysis of Incorrect Options:** * **B. Caries tooth:** While poor oral hygiene can occur in any patient, dental caries is not a specific or diagnostic opportunistic manifestation of HIV/AIDS. * **C. Cheilitis:** Angular cheilitis (inflammation of the corners of the mouth) can be seen in HIV due to secondary *Candida* infections or nutritional deficiencies, but it is non-specific and occurs in many other conditions (e.g., iron deficiency). * **D. Pharyngitis:** While acute HIV syndrome (seroconversion) can present with a sore throat, chronic oropharyngeal pharyngitis is not a defining opportunistic feature of HIV in the same way OHL is. **High-Yield Clinical Pearls for NEET-PG:** * **Diagnostic Significance:** OHL is considered a "highly suggestive" sign of HIV infection and often predicts the progression to AIDS. * **Histopathology:** Shows hyperkeratosis, parakeratosis, and "ballooning cells" in the upper layers of the epithelium. * **Treatment:** Usually, no specific treatment is required other than initiating **Antiretroviral Therapy (ART)**, which typically leads to the resolution of the lesions as the immune system recovers. * **Differential Diagnosis:** Must be distinguished from **Oral Candidiasis** (which is scrapable and shows pseudohyphae) and **Oral Leukoplakia** (a precancerous lesion associated with tobacco).

Q: Segmented RNA is found in which of the following viruses?

Influenza virus. **Explanation:** The correct answer is **Influenza virus**. The fundamental concept here is the genomic structure of RNA viruses. Most RNA viruses possess a single, continuous strand of RNA; however, a few families possess **segmented genomes**. **1. Why Influenza is correct:** Influenza virus belongs to the **Orthomyxoviridae** family. It contains a single-stranded, negative-sense RNA genome that is divided into **8 segments** (in Influenza A and B) or 7 segments (in Influenza C). This segmentation is clinically critical because it allows for **genetic reassortment** when two different strains infect the same cell, leading to **Antigenic Shift**. This shift results in major changes in surface glycoproteins (Hemagglutinin and Neuraminidase), causing periodic global pandemics. **2. Why other options are incorrect:** * **Rabies virus:** Belongs to the *Rhabdoviridae* family. It has a non-segmented, single-stranded, negative-sense RNA genome (bullet-shaped). * **Herpes virus:** This is a **DNA virus** (Double-stranded, linear DNA). Segmented genomes are a feature of specific RNA viruses, not DNA viruses. * **Molluscum contagiosum:** This belongs to the *Poxviridae* family. Like Herpes, it is a **DNA virus** (Double-stranded, linear DNA) and replicates in the cytoplasm. **High-Yield Clinical Pearls for NEET-PG:** To remember segmented RNA viruses, use the mnemonic **"BOAR"**: * **B**unyaviridae (3 segments) * **O**rthomyxoviridae (8 segments) * **A**renaviridae (2 segments) * **R**eoviridae (10-12 segments – *Note: Reovirus is Double-stranded RNA*) *Key Fact:* Segmented genomes = Potential for **Antigenic Shift** (Reassortment). Non-segmented genomes only undergo **Antigenic Drift** (Point mutations).

Q: Which carcinoma is associated with Epstein-Barr virus?

Carcinoma of the nasopharynx. **Explanation:** **Epstein-Barr Virus (EBV)**, also known as Human Herpesvirus 4 (HHV-4), is a potent oncogenic virus with a strong tropism for B-lymphocytes and epithelial cells. **Why Option C is Correct:** **Nasopharyngeal Carcinoma (NPC)**, specifically the undifferentiated type (WHO Type III), has a definitive causal association with EBV. The virus enters nasopharyngeal epithelial cells via the CD21 receptor (or through fusion mechanisms). Once inside, it establishes a **latency type II pattern**, expressing specific viral oncogenes like **LMP-1** (Latent Membrane Protein-1), which mimics CD40 signaling to promote cell survival and proliferation, leading to malignant transformation. This is particularly prevalent in Southern China and parts of Africa. **Why Other Options are Incorrect:** * **Options A & D (Larynx and Maxilla):** While Head and Neck Squamous Cell Carcinomas (HNSCC) are common, laryngeal and maxillary cancers are primarily linked to tobacco use, alcohol, and occasionally High-Risk HPV (for oropharyngeal sites), but not EBV. * **Option B (Bladder):** Carcinoma of the bladder is strongly associated with smoking, occupational exposure to aromatic amines (aniline dyes), and *Schistosoma haematobium* infection (Squamous cell type), but has no established link to EBV. **High-Yield Clinical Pearls for NEET-PG:** * **EBV-Associated Malignancies:** Burkitt Lymphoma (starry-sky appearance, t(8;14)), Hodgkin Lymphoma (Mixed cellularity), and Gastric Carcinoma (subset). * **Diagnostic Marker:** Elevated titers of **IgA antibodies against Viral Capsid Antigen (VCA)** are used for screening and monitoring recurrence in NPC. * **Non-Malignant EBV Disease:** Infectious Mononucleosis (Glandular fever) and Oral Hairy Leukoplakia (in HIV patients).

Q: Which organism's infection presents with clinical features resembling erythroblastosis fetalis?

Cytomegalovirus. **Explanation:** **Cytomegalovirus (CMV)** is the correct answer because its congenital presentation can closely mimic **Erythroblastosis Fetalis** (Rh incompatibility). Both conditions present with a clinical triad of **severe anemia, jaundice, and hepatosplenomegaly**. In severe cases, both can lead to **Hydrops Fetalis** (generalized fetal edema). CMV causes this by infecting the bone marrow and spleen, leading to extramedullary hematopoiesis and hemolysis, which mirrors the hemolytic process seen in Rh isoimmunization. **Analysis of Incorrect Options:** * **Toxoplasmosis:** While it presents with the "classic triad" of chorioretinitis, hydrocephalus, and intracranial calcifications, it does not typically present with the profound hemolytic picture or hydrops characteristic of erythroblastosis fetalis. * **Epstein-Barr Virus (EBV):** EBV is rarely a cause of congenital infections. It typically causes infectious mononucleosis in adolescents and is not associated with the erythroblastosis-like presentation in neonates. * **Herpes Simplex Virus (HSV):** Congenital HSV usually presents with the SEM triad (Skin, Eye, and Mouth vesicles), encephalitis, or disseminated multi-organ failure, rather than isolated hemolytic anemia and hydrops. **NEET-PG High-Yield Pearls:** * **CMV** is the most common intrauterine viral infection. * **Key Diagnostic Feature:** Look for **periventricular calcifications** (vs. diffuse calcifications in Toxoplasmosis). * **Histology:** "Owl’s eye" intranuclear inclusion bodies. * **Clinical Clue:** "Blueberry muffin" spots (extramedullary hematopoiesis) are common in CMV and Rubella. * **Treatment:** Ganciclovir/Valganciclovir is the drug of choice for symptomatic neonatal CMV.

Q: Which of the following viruses is known for latency?

Herpes Simplex Virus 2 (HSV-2). ### Explanation **Correct Option: A. Herpes Simplex Virus 2 (HSV-2)** Latency is a hallmark of the **Herpesviridae** family. After the primary infection, the virus remains in a non-replicating state within the host's cells for life. Specifically, **HSV-2** establishes latency in the **sacral ganglia** (S2-S4). Periodic reactivation can occur, triggered by stress, fever, or immunosuppression, leading to recurrent genital herpes. **Analysis of Incorrect Options:** * **B. Cytomegalovirus (CMV):** While CMV is also a member of the Herpesviridae family and *does* exhibit latency (primarily in myeloid progenitor cells and monocytes), in the context of standard NEET-PG questions, HSV is the classic prototype for "latency" due to its well-defined neurotropism and sensory ganglia involvement. However, if this were a "multiple correct" format, CMV would also be technically correct. In single-best-answer formats, HSV is the preferred choice. * **C. Rotavirus:** This is a Reovirus that causes acute gastroenteritis. It does not establish latency; it causes an acute, self-limiting infection and is cleared by the immune system or shed in feces. * **D. HIV:** HIV is a Retrovirus characterized by **persistence**, not classical latency. It undergoes continuous active replication and integrates into the host genome (provirus). While "latent reservoirs" exist in resting T-cells, the clinical hallmark is chronic progression rather than the "dormancy-reactivation" cycle seen in Herpesviruses. **High-Yield Clinical Pearls for NEET-PG:** * **Site of Latency:** HSV-1 (Trigeminal ganglia); HSV-2 (Sacral ganglia); VZV (Dorsal root ganglia); EBV (B-cells). * **Diagnosis:** Tzanck smear showing **Multinucleated Giant Cells** (Cowdry Type A inclusion bodies) is characteristic of HSV and VZV. * **Drug of Choice:** Acyclovir is the mainstay for treating HSV-2 outbreaks and suppressive therapy.

Q: Hepatitis A is transmitted by which route?

Feco-oral route. **Explanation:** **Hepatitis A Virus (HAV)** is a non-enveloped, single-stranded RNA virus belonging to the *Picornaviridae* family. The correct answer is the **feco-oral route**, which is the primary mode of transmission. The virus is excreted in the feces of infected individuals; transmission occurs through the ingestion of contaminated water or food (especially raw shellfish) and via person-to-person contact due to poor hand hygiene. **Analysis of Options:** * **Feco-oral route (Correct):** HAV is acid-stable, allowing it to survive the gastric barrier. It replicates in the liver and is shed in high concentrations in bile and stool. * **Blood route (Incorrect):** Unlike Hepatitis B, C, and D, HAV has a very brief period of viremia. Transmission via blood transfusion or needle sticks is extremely rare and not a significant public health route. * **Inhalation (Incorrect):** HAV is not a respiratory pathogen; it does not colonize the respiratory mucosa or spread via droplets. * **Sexual contact (Incorrect):** While transmission can occur during sexual activity (specifically oral-anal contact), this is essentially a variation of the feco-oral route rather than transmission via genital secretions. **High-Yield Clinical Pearls for NEET-PG:** * **Incubation Period:** Short (2–6 weeks). * **Chronicity:** HAV **never** causes chronic infection or a carrier state. * **Diagnosis:** **IgM anti-HAV** is the gold standard for acute infection. **IgG anti-HAV** indicates past infection or vaccination (lifelong immunity). * **Prophylaxis:** Killed vaccine is available. Post-exposure prophylaxis (PEP) involves the vaccine or immunoglobulin (HNIG) depending on the patient's age and health status. * **Epidemiology:** Often associated with overcrowding and poor sanitation; common in travelers to endemic areas.

Q: Which of the following is associated with Hepatitis C virus (HCV)?

Anti-LKM-1 antibody. **Explanation:** The correct answer is **Anti-LKM-1 antibody**. **1. Why Anti-LKM-1 is correct:** Anti-Liver Kidney Microsomal type 1 (Anti-LKM-1) antibodies are the hallmark of **Autoimmune Hepatitis (AIH) Type 2**. Interestingly, there is a well-documented molecular mimicry between the Hepatitis C Virus (HCV) and the cytochrome P450 2D6 antigen. Consequently, up to 10% of patients with chronic HCV infection test positive for Anti-LKM-1 antibodies. This makes it a high-yield association for differentiating viral-induced autoimmunity from primary AIH. **2. Analysis of Incorrect Options:** * **Scleroderma:** This is a systemic connective tissue disorder characterized by fibrosis. It is associated with **Anti-centromere** (Limited/CREST) and **Anti-Scl-70** (Diffuse) antibodies, not HCV. * **Cryoglobulinemia:** While **Mixed Cryoglobulinemia (Type II and III)** is strongly associated with HCV, the question asks for the *most specific* immunological marker listed. In many NEET-PG patterns, if both are present, Anti-LKM-1 is tested as the specific antibody association, though Cryoglobulinemia remains the most common extrahepatic manifestation. * **Polyarteritis Nodosa (PAN):** This systemic necrotizing vasculitis is classically associated with **Hepatitis B Virus (HBV)**, not HCV. **3. NEET-PG High-Yield Pearls:** * **HCV & Autoimmunity:** HCV is the "great masquerader" of virology, associated with Lichen Planus, Porphyria Cutanea Tarda, and Membranoproliferative Glomerulonephritis (MPGN). * **LKM Antibody Types:** * **LKM-1:** HCV and AIH Type 2. * **LKM-2:** Drug-induced hepatitis (Ticrynafen). * **LKM-3:** Hepatitis D Virus (HDV). * **HBV vs. HCV:** Remember: **HBV = PAN**; **HCV = Cryoglobulinemia.**

Q: Japanese Encephalitis is transmitted by which mosquito species?

All of the above. **Explanation:** Japanese Encephalitis (JE) is the leading cause of viral encephalitis in Asia, caused by a Flavivirus. It is a zoonotic disease where the virus is maintained in an **enzootic cycle** involving mosquitoes as vectors and pigs or water birds (Ardeid birds) as reservoirs. **Why "All of the above" is correct:** The primary vectors for Japanese Encephalitis are mosquitoes of the **Culex vishnui subgroup**. This subgroup consists of three main species that are all competent vectors: 1. **Culex tritaeniorhynchus:** This is the **most important and principal vector** across most of Asia, including India. It breeds predominantly in stagnant water like rice fields. 2. **Culex vishnui:** A significant vector that contributes to transmission in rural areas. 3. **Culex pseudovishnui:** Also a proven vector within the same subgroup. Since all three species belong to the primary vector group responsible for the transmission of the JE virus to humans, option D is the correct choice. **High-Yield Clinical Pearls for NEET-PG:** * **Reservoirs:** Pigs are considered "amplifier hosts" (they develop high viremia), while Ardeid birds (herons, egrets) are the natural reservoir hosts. * **Dead-end Hosts:** Humans and horses are "dead-end hosts" because they do not develop sufficient viremia to infect feeding mosquitoes. * **Seasonality:** Transmission usually peaks during the rainy season and pre-harvest periods (due to rice field irrigation). * **Diagnosis:** The investigation of choice is **MAC-ELISA** to detect IgM antibodies in CSF or serum. * **Vaccination:** The **SA-14-14-2** (live attenuated) vaccine is commonly used in the Universal Immunization Programme (UIP) in endemic areas of India.

Q: What are bacteriophages?

Viruses that infect bacteria. **Explanation:** **Bacteriophages** (often simply called "phages") are obligate intracellular **viruses** that specifically target and replicate within **bacteria**. The term literally translates to "bacteria eater" (from the Greek *phagein*, meaning "to devour"). They function by attaching to specific receptors on the bacterial cell wall, injecting their genetic material (DNA or RNA), and hijacking the host’s metabolic machinery to produce new viral particles. **Analysis of Options:** * **Option B (Correct):** Bacteriophages are viral entities. They play a crucial role in bacterial genetics through **transduction**, where they transfer DNA from one bacterium to another, often spreading antibiotic resistance or virulence factors. * **Option A:** This is biologically impossible; bacteria are complex cellular organisms and cannot "infect" a virus, which is a non-cellular genetic entity. * **Options C & D:** Viruses or bacteria that infect protozoa are distinct categories (e.g., *Acanthamoeba polyphaga mimivirus*). Bacteriophages are strictly host-specific to bacteria. **High-Yield Clinical Pearls for NEET-PG:** 1. **Life Cycles:** Phages exhibit two main cycles: **Lytic** (virulent phages cause cell lysis) and **Lysogenic** (temperate phages integrate their DNA into the bacterial chromosome as a **prophage**). 2. **Lysogenic Conversion:** This is a high-yield concept where a non-pathogenic bacterium becomes pathogenic after being infected by a temperate phage. Examples include: * *Corynebacterium diphtheriae* (Toxin production via **Beta-phage**) * *Vibrio cholerae* (CTX phage) * *Streptococcus pyogenes* (Erythrogenic toxin) * *Clostridium botulinum* (Botulinum toxin) 3. **Phage Typing:** Used in epidemiology to track the source of outbreaks (e.g., *Staphylococcus aureus* or *Salmonella Typhi*) by identifying the specific phage strains that lyse the bacteria.

Question 1

What is the oropharyngeal manifestation of HIV infection?

Accepted Answer

Oral hairy leukoplakia

Answer

Caries tooth

Answer

Cheilitis

Answer

Pharyngitis

Question 2

Segmented RNA is found in which of the following viruses?

Accepted Answer

Influenza virus

Answer

Rabies virus

Answer

Herpes virus

Answer

Molluscum contagiosum

Question 3

Which carcinoma is associated with Epstein-Barr virus?

Accepted Answer

Carcinoma of the nasopharynx

Answer

Carcinoma of the larynx

Answer

Carcinoma of the bladder

Answer

Carcinoma of the maxilla

Question 4

Which organism's infection presents with clinical features resembling erythroblastosis fetalis?

Accepted Answer

Cytomegalovirus

Answer

Toxoplasmosis

Answer

Epstein Barr virus

Answer

Herpes virus

Question 5

Which of the following viruses is known for latency?

Accepted Answer

Herpes Simplex Virus 2 (HSV-2)

Answer

Cytomegalovirus (CMV)

Answer

Rotavirus

Answer

Human Immunodeficiency Virus (HIV)

Question 6

Hepatitis A is transmitted by which route?

Accepted Answer

Feco-oral route

Answer

Blood route

Answer

Inhalation

Answer

Sexual contact

Question 7

Which of the following is associated with Hepatitis C virus (HCV)?

Accepted Answer

Anti-LKM-1 antibody

Answer

Scleroderma

Answer

Cryoglobulinemia

Answer

Polyarteritis nodosa

Question 8

Japanese Encephalitis is transmitted by which mosquito species?

Accepted Answer

All of the above

Answer

Culex tritaeniorhynchus

Answer

Culex vishnui

Answer

Culex pseudovishnui

Question 9

What are bacteriophages?

Accepted Answer

Viruses that infect bacteria

Answer

Bacteria that infect viruses

Answer

Viruses that infect protozoa

Answer

Bacteria that infect protozoa

Question 10

A VDRL reactive mother gave birth to an infant. All of the following would help in determining the risk of transmission to the infant, EXCEPT?

Accepted Answer

TPHA test on the serum sample of the infant

Answer

TPHA test on the serum sample of the mother

Answer

VDRL on the paired serum sample of the infant and mother

Answer

Time interval between the treatment of the mother and her delivery

Virology — MCQs

Virology — MCQs

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