Virology Practice Questions

Q: Which of the following is NOT true about the dengue virus?

DEN 4 is the most common serotype in India.. **Explanation:** **1. Why Option B is the correct answer (The False Statement):** While all four serotypes (DEN 1–4) circulate in India, **DEN 2** has historically been the most common and dominant serotype associated with severe outbreaks and Dengue Hemorrhagic Fever (DHF). Recent epidemiological shifts have shown a rise in DEN 1 and DEN 3 in certain regions, but **DEN 4** remains the least common serotype in the Indian subcontinent. **2. Analysis of Incorrect Options (True Statements):** * **Option A:** Dengue virus is a member of the genus *Flavivirus* within the **Flaviviridae** family. * **Option C:** The primary vector is ***Aedes aegypti*** (the "Tiger mosquito," a day-biter that breeds in artificial collections of clean water). ***Aedes albopictus*** is the secondary vector. * **Option D:** The virus possesses a **single-stranded, positive-sense RNA** genome, which is enveloped and icosahedral in symmetry. **3. Clinical Pearls for NEET-PG:** * **Antibody-Dependent Enhancement (ADE):** This occurs when a person is infected with a different serotype for the second time. Non-neutralizing antibodies from the first infection facilitate viral entry into macrophages, leading to a massive cytokine storm and **Dengue Hemorrhagic Fever (DHF)** or **Dengue Shock Syndrome (DSS)**. * **Diagnosis:** * **NS1 Antigen:** Best marker for early diagnosis (Day 1–5). * **IgM ELISA:** Appears after Day 5 (indicates current/recent infection). * **IgG ELISA:** Indicates past infection or secondary infection if titers are very high. * **Tourniquet Test:** A positive test (≥10 petechiae per square inch) is a clinical indicator of capillary fragility in DHF.

Q: Which is the usual marker for the detection of hepatitis B infection?

Hepatitis B surface antigen (HBsAg). **Explanation:** **Hepatitis B surface antigen (HBsAg)** is the correct answer because it is the first serological marker to appear in the blood after infection, typically detectable 2 to 8 weeks before clinical symptoms or biochemical evidence (elevated ALT/AST) emerge. It indicates that the virus is present in the body (acute or chronic) and is the primary screening tool used to identify an active HBV infection. **Analysis of Incorrect Options:** * **Hepatitis B surface antibody (HBsAb/anti-HBs):** This marker indicates immunity. It appears after the disappearance of HBsAg or following successful vaccination. It is not used to detect an active infection but rather to confirm recovery or immune status. * **Hepatitis B core antigen (HBcAg):** This is an internal component of the virion. It is sequestered within the HBsAg coat and is **not** detectable in the serum; it can only be found in infected hepatocytes via biopsy. * **Hepatitis B core antibody (HBcAb/anti-HBc):** While IgM anti-HBc is a marker of acute infection (and the only marker positive during the "window period"), total anti-HBc indicates past or current infection but does not distinguish between the two as reliably as HBsAg for initial screening. **High-Yield Clinical Pearls for NEET-PG:** * **Window Period:** The interval between the disappearance of HBsAg and the appearance of anti-HBs. During this time, **IgM anti-HBc** is the most reliable diagnostic marker. * **Chronic Infection:** Defined by the persistence of HBsAg in the blood for more than 6 months. * **Infectivity Marker:** **HBeAg** (Envelope antigen) indicates high viral replication and high infectivity. * **Vaccine Response:** A person vaccinated against HBV will be positive for **anti-HBs** only (negative for anti-HBc).

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: 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: Coxsackie virus can be isolated by inoculating into which of the following?

Suckling mice. **Explanation:** The **Coxsackie virus**, a member of the *Picornaviridae* family (Genus: *Enterovirus*), is uniquely characterized by its pathogenicity in **suckling mice** (mice less than 48 hours old). This is the gold standard classical method for isolation and differentiation of the virus into two groups: * **Group A:** Causes widespread **flaccid paralysis** due to generalized myositis of skeletal muscles. * **Group B:** Causes **spastic paralysis** due to focal myositis and necrotizing steatitis (inflammation of brown fat), often involving the pancreas and CNS. **Analysis of Incorrect Options:** * **A & B (Rabbit and Guinea Pig):** These animals are commonly used for producing antisera or for specific tests like the Paul-Bunnell test (Sheep RBCs) or Koch’s phenomenon (Tubercle bacilli), but they are not the primary isolation media for Coxsackie viruses. * **D (Foot pad of mice):** This is the specific site used for the cultivation of ***Mycobacterium leprae*** (the Shepard’s model), as the bacteria prefer the cooler temperature of the extremities. **High-Yield Clinical Pearls for NEET-PG:** * **Hand-Foot-Mouth Disease (HFMD):** Most commonly caused by Coxsackie **A16** and Enterovirus 71. * **Herpangina:** Characterized by vesicular lesions on the soft palate/fauces, caused by Group A. * **Bornholm Disease (Pleurodynia):** Also known as "Devil’s Grip," caused by Group B. * **Myocarditis & Dilated Cardiomyopathy:** Most frequently associated with **Coxsackie B** infections. * **Aseptic Meningitis:** Can be caused by both groups, but Group B is a more common culprit.

Q: Which of the following cell types is NOT a target for the initiation and maintenance of HIV infection?

Neutrophil. ### Explanation The primary mechanism of HIV entry into host cells depends on the interaction between the viral envelope glycoprotein **gp120** and the host cell **CD4 receptor**, along with co-receptors (**CCR5** or **CXCR4**). **Why Neutrophils are the Correct Answer:** Neutrophils (Option D) do not express the CD4 receptor on their surface. Therefore, they cannot be directly infected by HIV. While HIV infection can lead to secondary "neutropenia" or functional defects in neutrophils due to a compromised cytokine environment, these cells are not targets for viral entry, replication, or maintenance. **Analysis of Incorrect Options:** * **CD4 T cells (Option A):** These are the primary targets for HIV. The virus binds to CD4 and the CXCR4 co-receptor (T-tropic strains), leading to progressive depletion of these cells, which is the hallmark of AIDS. * **Macrophages (Option B):** Macrophages express CD4 and the **CCR5** co-receptor (M-tropic strains). They are resistant to the cytopathic effects of the virus, allowing them to serve as long-term **reservoirs** for HIV and transport the virus to the brain. * **Dendritic Cells (Option C):** These cells (including follicular dendritic cells and Langerhans cells) play a crucial role in the **initiation** of infection. They capture HIV in mucosal surfaces using the **DC-SIGN** receptor and transport the virus to regional lymph nodes, effectively "presenting" it to CD4 T cells. **High-Yield Clinical Pearls for NEET-PG:** * **Primary Receptor:** CD4. * **Co-receptors:** CCR5 (early infection/macrophages) and CXCR4 (late infection/T cells). * **Homozygous mutation in CCR5 (Δ32):** Confers resistance to HIV infection. * **Viral Entry Protein:** gp120 (attachment); gp41 (fusion). * **Reservoirs:** Macrophages and Memory CD4 T cells are the major anatomical and cellular reservoirs that prevent total viral clearance.

Q: Which of the following groups of viruses is most likely involved in viral meningitis?

Enterovirus. **Explanation:** **Enteroviruses** (specifically Coxsackievirus A and B, and Echoviruses) are the most common cause of viral (aseptic) meningitis worldwide, accounting for more than **85–90% of all cases**. They belong to the *Picornaviridae* family. These viruses typically follow a fecal-oral route of transmission, replicate in the pharynx and GI tract, and then spread hematogenously to the central nervous system. Clinical presentation usually includes fever, headache, photophobia, and meningeal signs, often occurring in seasonal outbreaks (summer and autumn). **Why other options are incorrect:** * **Adenovirus:** While it can cause respiratory infections, conjunctivitis, and hemorrhagic cystitis, it is a rare cause of meningitis, usually seen only in immunocompromised individuals. * **Human Papilloma Virus (HPV):** This virus is strictly epitheliotropic, causing cutaneous warts and mucosal lesions (including cervical cancer). It does not have a neurotropic phase and does not cause meningitis. * **Poxvirus:** This group (including Variola and Molluscum contagiosum) primarily causes skin lesions. While complications can occur, they are not standard causes of viral meningitis. **High-Yield Clinical Pearls for NEET-PG:** * **CSF Findings in Viral Meningitis:** Normal glucose, normal to slightly elevated protein, and **lymphocytic pleocytosis** (though neutrophils may predominate in the first 24 hours). * **Mollaret Meningitis:** Recurrent lymphocytic meningitis often associated with **HSV-2**. * **Most common cause of Viral Encephalitis:** Sporadic cases are most commonly caused by **HSV-1** (targeting the temporal lobes). * **Enterovirus 71:** Notable for causing Hand-Foot-Mouth Disease (HFMD) and severe neurological complications like brainstem encephalitis.

Q: Teratogenic effects are rare with which of the following infections?

Human Immunodeficiency Virus (HIV). ### Explanation The correct answer is **Human Immunodeficiency Virus (HIV)**. **1. Why HIV is the correct answer:** While HIV is frequently transmitted from mother to child (Vertical Transmission) via the placenta, during delivery, or through breastfeeding, it is **not typically teratogenic**. HIV infection in utero does not cause structural malformations or a specific dysmorphic syndrome. Instead, it leads to pediatric HIV/AIDS, characterized by failure to thrive, recurrent infections, and CD4 depletion. **2. Why the other options are incorrect:** The other options are classic members of the **TORCH** group of infections, which are notorious for causing structural defects when acquired during pregnancy: * **Rubella:** Causes **Congenital Rubella Syndrome (CRS)**, characterized by the triad of cataracts, sensorineural deafness, and cardiac defects (PDA). It has the highest teratogenic potential if acquired in the first trimester. * **Cytomegalovirus (CMV):** The most common viral cause of congenital anomalies. It leads to microcephaly, periventricular calcifications, and sensorineural hearing loss. * **Varicella:** Infection during the first 20 weeks can lead to **Congenital Varicella Syndrome**, presenting with cicatricial skin scarring, limb hypoplasia, and chorioretinitis. **3. NEET-PG High-Yield Pearls:** * **Most common congenital infection:** CMV. * **Highest risk of malformation:** Rubella (especially if contracted <12 weeks gestation). * **HIV Management:** To prevent vertical transmission, the mother should be on HAART regardless of CD4 count, and the neonate should receive Zidovudine prophylaxis. * **Parvovirus B19:** Another important viral infection in pregnancy; it is not typically structural-teratogenic but causes **Hydrops Fetalis** due to severe fetal anemia.

Question 1

Which of the following is NOT true about the dengue virus?

Accepted Answer

DEN 4 is the most common serotype in India.

Answer

It belongs to the Flaviviridae family.

Answer

The main vectors are Aedes aegypti and Aedes albopictus.

Answer

The virus has positive-sense RNA.

Question 2

Which is the usual marker for the detection of hepatitis B infection?

Accepted Answer

Hepatitis B surface antigen (HBsAg)

Answer

Hepatitis B surface antibody (HBsAb)

Answer

Hepatitis B core antigen (HBcAg)

Answer

Hepatitis B core antibody (HBcAb)

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

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 7

Coxsackie virus can be isolated by inoculating into which of the following?

Accepted Answer

Suckling mice

Answer

Rabbit

Answer

Guinea pig

Answer

Foot pad of mice

Question 8

Which of the following cell types is NOT a target for the initiation and maintenance of HIV infection?

Accepted Answer

Neutrophil

Answer

CD4 T cell

Answer

Macrophage

Answer

Dendritic cell

Question 9

Which of the following groups of viruses is most likely involved in viral meningitis?

Accepted Answer

Enterovirus

Answer

Adenovirus

Answer

Human papilloma virus

Answer

Poxvirus

Question 10

Teratogenic effects are rare with which of the following infections?

Accepted Answer

Human Immunodeficiency Virus (HIV)

Answer

Cytomegalovirus (CMV)

Answer

Rubella

Answer

Varicella

Virology — MCQs

Virology — MCQs

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