Virology Practice Questions

Q: Which family do all oncogenic viruses containing RNA belong to?

Retroviridae. **Explanation:** The correct answer is **Retroviridae**. **1. Why Retroviridae is correct:** Oncogenic RNA viruses are primarily found within the Retroviridae family. These viruses possess the enzyme **reverse transcriptase**, which allows them to convert their RNA genome into DNA. This DNA is then integrated into the host cell's genome as a "provirus." Once integrated, they can induce neoplastic transformation through two main mechanisms: * **Transducing viruses:** Carrying viral oncogenes (v-onc) directly into the host (e.g., Rous Sarcoma Virus). * **Cis-activation:** Integrating near a host proto-oncogene and activating it via viral promoters (e.g., Human T-cell Lymphotropic Virus - HTLV-1, which causes Adult T-cell Leukemia/Lymphoma). **2. Why the other options are incorrect:** * **Picornaviridae (Option A):** These are small, non-enveloped RNA viruses (e.g., Poliovirus, Hepatitis A). They do not integrate into the host genome and are not associated with oncogenesis. * **Herpesviridae (Option B):** While this family contains several potent oncogenic viruses (e.g., EBV causing Burkitt lymphoma; HHV-8 causing Kaposi sarcoma), they are **DNA viruses**, not RNA viruses. **3. High-Yield Clinical Pearls for NEET-PG:** * **HTLV-1** is the only retrovirus directly linked to human cancer. * **Hepatitis C Virus (HCV)** is an RNA virus (Flaviviridae) associated with Hepatocellular Carcinoma, but it is an exception; it is oncogenic primarily through chronic inflammation and indirect mechanisms rather than genomic integration. * **DNA Oncogenic Viruses to remember:** HPV (16, 18), EBV, HBV, and HHV-8. * **Key Enzyme:** Reverse transcriptase is the hallmark of Retroviridae, making them unique among RNA viruses for their stable integration into host DNA.

Q: Which of the following investigations is used in the detection and confirmation of HIV?

Reverse Transcriptase-PCR. **Explanation:** The correct answer is **Reverse Transcriptase-PCR (RT-PCR)**. **Why RT-PCR is the Correct Answer:** HIV is a **Retrovirus**, meaning its genetic material is composed of single-stranded RNA (ssRNA). Standard Polymerase Chain Reaction (PCR) can only amplify DNA. To detect HIV RNA, the enzyme **Reverse Transcriptase** must first convert the viral RNA into complementary DNA (cDNA), which is then amplified. This process is known as RT-PCR. It is the gold standard for the early detection of HIV (during the window period before antibodies appear) and for diagnosing HIV in infants born to HIV-positive mothers, where maternal antibodies might interfere with serological tests. **Analysis of Incorrect Options:** * **A. Polymerase Chain Reaction (PCR):** Standard PCR is used for DNA amplification. While "DNA PCR" can be used to detect HIV proviral DNA integrated into host cells, RT-PCR is the specific technique required to detect the free viral RNA circulating in the plasma. * **C. Real-Time PCR:** While Real-Time PCR (qPCR) is used to *quantify* the viral load (monitoring treatment efficacy), the fundamental step required to handle the HIV RNA genome is the Reverse Transcription step. * **D. Mimic PCR:** This is a specialized technique used primarily for quantification by using an internal control (mimic) to account for tube-to-tube variation; it is not the primary diagnostic modality for HIV. **Clinical Pearls for NEET-PG:** * **Screening Test:** ELISA (High sensitivity). * **Confirmatory Test (Traditional):** Western Blot (Detects antibodies against gp41, gp120, and p24). Note: Recent guidelines favor Fourth Generation Immunoassays and Nucleic Acid Testing (NAT). * **Early Marker:** p24 antigen (appears before antibodies). * **Best Indicator of Prognosis:** CD4+ T-cell count. * **Best Indicator of Treatment Efficacy:** Viral load (measured via RT-PCR).

Q: Renal involvement is seen in which of the following infections?

Polyoma virus. **Explanation:** The **Polyomaviridae** family, specifically the **BK and JC viruses**, are classic "nephrotropic" viruses. After a primary respiratory infection in childhood, these viruses remain latent in the **renal tubular epithelium**. In immunocompromised states (e.g., renal transplant recipients), the BK virus reactivates, leading to **BK virus-associated nephropathy (BKVAN)** and hemorrhagic cystitis. The JC virus, while primarily known for Progressive Multifocal Leukoencephalopathy (PML), also persists in the kidneys and is excreted in the urine. **Analysis of Options:** * **Polyoma virus (Correct):** It is the most direct answer because the kidney is its primary site of latency and clinical manifestation (BKVAN). * **Cytomegalovirus (CMV):** While CMV can be detected in urine and may cause systemic disease in transplant patients, it primarily targets the lungs (pneumonitis), retina (retinitis), and GI tract rather than being primarily defined by renal involvement. * **Human Papilloma virus (HPV):** HPV is strictly epitheliotropic, targeting the skin and mucosal surfaces (warts, cervical cancer). It does not involve the renal parenchyma. * **HIV:** While HIV can cause "HIV-Associated Nephropathy" (HIVAN), the virus itself infects CD4+ T cells and macrophages. The renal damage is a secondary complication of the systemic infection rather than the virus being primarily nephrotropic. **High-Yield Clinical Pearls for NEET-PG:** * **Decoy Cells:** Look for these in urine cytology; they are renal tubular cells with enlarged, basophilic intranuclear inclusions characteristic of Polyoma virus (BK virus). * **BK Virus:** "B" is for **B**ad **K**idney (Nephropathy/Ureteric stenosis). * **JC Virus:** "J" is for **J**unk **C**erebrum (PML). * **SV40:** A simian polyomavirus known for its potential oncogenic properties in laboratory settings.

Q: All the following viruses are known to cause Lymphomas except:

Japanese Encephalitis virus. **Explanation:** The correct answer is **Japanese Encephalitis Virus (JEV)** because it is a neurotropic virus belonging to the *Flaviviridae* family. It primarily causes acute encephalitis (inflammation of the brain parenchyma) and is not associated with oncogenesis or the development of malignancies like lymphoma. **Analysis of Options:** * **HTLV-I (Human T-cell Leukemia Virus-1):** This retrovirus is the definitive causative agent of **Adult T-cell Leukemia/Lymphoma (ATLL)**. It integrates into the host genome and utilizes the *Tax* protein to drive uncontrolled T-cell proliferation. * **EBV (Epstein-Barr Virus/HHV-4):** A highly oncogenic herpesvirus associated with several B-cell lymphomas, including **Burkitt Lymphoma** (starry-sky appearance), Hodgkin Lymphoma, and Diffuse Large B-cell Lymphoma (DLBCL), especially in immunocompromised patients. * **KSHV/HHV-8 (Kaposi Sarcoma-associated Herpesvirus):** Beyond causing Kaposi Sarcoma, this virus is the primary driver of **Primary Effusion Lymphoma (PEL)** and Multicentric Castleman Disease. **High-Yield NEET-PG Pearls:** * **Oncogenic DNA Viruses:** EBV, HHV-8, HBV, HPV (16, 18), and Merkel Cell Polyomavirus. * **Oncogenic RNA Viruses:** HTLV-1 and HCV (HCV is associated with B-cell Non-Hodgkin Lymphoma). * **JEV Key Fact:** It is transmitted by the *Culex tritaeniorhynchus* mosquito; the "amplifier host" is the pig. It is the most common cause of epidemic viral encephalitis in India. * **Burkitt Lymphoma Marker:** Associated with the **t(8;14)** translocation involving the *c-myc* gene.

Q: Which type of hepatitis is enterically transmitted?

Hepatitis E. **Explanation:** The transmission of viral hepatitis is broadly categorized into two routes: **Enteric** (fecal-oral) and **Parenteral** (blood-borne/sexual). **1. Why Hepatitis E is Correct:** Hepatitis E virus (HEV) is a non-enveloped RNA virus transmitted primarily via the **fecal-oral route**, usually through contaminated water. It is the most common cause of acute viral hepatitis worldwide. In the context of NEET-PG, it is crucial to remember that **Hepatitis A and E** are the two "Vowels" that are transmitted enterically ("The vowels go to the bowels"). **2. Why the other options are incorrect:** * **Hepatitis C (HCV):** Primarily transmitted through **parenteral** routes (blood transfusion, IV drug use). It is notorious for having a high rate of progression to chronic hepatitis and cirrhosis. * **Hepatitis D (HDV):** A defective virus that requires the presence of Hepatitis B (HBsAg) to replicate. It is transmitted **parenterally** or sexually, occurring as either a co-infection or super-infection. * **Hepatitis F:** This is a hypothetical virus. While early reports suggested its existence, it is not recognized as a distinct clinical entity in modern virology. **Clinical Pearls for NEET-PG:** * **Pregnancy Warning:** HEV is associated with high mortality (up to 20%) in **pregnant women**, particularly during the third trimester, due to fulminant hepatic failure. * **Zoonosis:** HEV genotype 3 is often transmitted through undercooked pork or deer meat. * **Chronicity:** While HEV is usually acute, it can cause chronic hepatitis in **immunocompromised** patients (e.g., organ transplant recipients). * **Family:** HEV belongs to the *Hepeviridae* family.

Q: Which cells does HIV selectively infect and destroy?

T4 cells. **Explanation:** The Human Immunodeficiency Virus (HIV) is a retrovirus that primarily targets the immune system by binding to the **CD4 receptor**. **1. Why T4 cells are correct:** T4 cells, also known as **CD4+ T-helper cells**, are the primary targets of HIV. The viral envelope glycoprotein **gp120** binds with high affinity to the CD4 molecule expressed on the surface of these T-lymphocytes. Once inside, the virus replicates and eventually leads to the destruction of these cells. The progressive depletion of T4 cells results in profound immunosuppression, the hallmark of AIDS. **2. Why other options are incorrect:** * **T3 cells:** This is a misnomer in this context. While CD3 is a pan-T cell marker found on all T-lymphocytes, the term "T3 cells" is not standard nomenclature for a specific functional subset like T4 or T8. * **K cells (Killer cells):** These usually refer to Natural Killer (NK) cells or cells involved in Antibody-Dependent Cellular Cytotoxicity (ADCC). While HIV can affect the overall immune environment, it does not selectively infect or destroy these cells via the CD4 pathway. * **T10 cells:** This is not a standard classification for T-lymphocyte subsets in clinical immunology. **Clinical Pearls for NEET-PG:** * **Coreceptors:** Besides CD4, HIV requires coreceptors for entry: **CCR5** (found on macrophages; important in early infection) and **CXCR4** (found on T-cells; associated with late-stage progression). * **Markers of Progression:** The **CD4+ T-cell count** is the best indicator of the patient's immune status, while **Viral Load (HIV RNA)** is the best predictor of disease progression. * **Inversion of Ratio:** In HIV infection, the normal CD4:CD8 ratio (typically 2:1) is **inverted** (becomes <1:1).

Q: The overall effect of HIV is to gradually impair the immune system by interference with which of the following?

Helper T lymphocytes. **Explanation:** The hallmark of HIV pathogenesis is the progressive depletion and dysfunction of **CD4+ Helper T lymphocytes**. HIV specifically targets these cells because the **gp120** protein on the viral envelope has a high affinity for the **CD4 receptor** and co-receptors (CCR5 or CXCR4). Once inside, the virus replicates, leading to cell death via pyroptosis, direct viral lysis, and syncytia formation. Since Helper T cells are the "master orchestrators" of the immune system—activating both B-cells for antibody production and CD8+ T-cells for cell-mediated immunity—their loss leads to profound immunosuppression and AIDS. **Analysis of Incorrect Options:** * **Natural Killer (NK) cells:** While NK cell function may decline in late-stage HIV due to a lack of cytokines (like IL-2) normally provided by Helper T cells, they are not the primary target or the cause of the initial immune impairment. * **Plasma cells:** These are terminally differentiated B-cells. HIV does not infect them directly. Although B-cell function becomes dysregulated (leading to hypergammaglobulinemia), this is a secondary effect of T-cell dysfunction. * **Macrophages:** While macrophages express CD4 and serve as important **viral reservoirs** (especially in the CNS), they are relatively resistant to the cytopathic effects of HIV. They do not undergo the same massive depletion as Helper T cells. **High-Yield NEET-PG Pearls:** * **Primary Receptor:** CD4 molecule. * **Co-receptors:** **CCR5** (predominant in early/mucosal infection; M-tropic) and **CXCR4** (late-stage/T-mropic). * **Diagnosis:** Screening by ELISA; Confirmation by Western Blot (detecting gp120/160, gp41, p24). * **Monitoring:** CD4+ T-cell count is the best indicator of immune status, while Viral Load (RNA) is the best predictor of disease progression.

Q: A patient, two months post-renal transplantation, presents with difficulty in breathing. X-ray shows bilateral diffuse interstitial pneumonia. What is the most probable etiologic agent?

Cytomegalovirus (CMV). ### **Explanation** **Correct Option: A. Cytomegalovirus (CMV)** Cytomegalovirus is the most common viral opportunistic infection in solid organ transplant (SOT) recipients, typically manifesting **1 to 6 months post-transplantation** (the period of maximal immunosuppression). In renal transplant patients, CMV classically presents as **interstitial pneumonia**, fever, and leukopenia. The radiological finding of bilateral diffuse interstitial infiltrates is a hallmark of CMV pneumonitis in this clinical context. **Analysis of Incorrect Options:** * **B. Histoplasma capsulatum:** While it can cause fungal pneumonia in immunocompromised hosts, it is geographically restricted (endemic areas) and usually presents with granulomatous lesions or mediastinal lymphadenopathy rather than diffuse interstitial pneumonia 2 months post-op. * **C. Candida species:** Candida is a common cause of oral thrush or candidemia in transplant patients, but it is a very rare cause of primary interstitial pneumonia. * **D. Pneumocystis jirovecii (PJP):** PJP presents similarly with diffuse interstitial infiltrates. However, due to the routine use of **Trimethoprim-Sulfamethoxazole (TMP-SMX) prophylaxis** in the first 6–12 months post-transplant, its incidence has significantly decreased, making CMV the more statistically probable answer in modern clinical scenarios. **High-Yield Clinical Pearls for NEET-PG:** * **Timeline:** CMV is the "King of the Middle Period" (1–6 months post-transplant). * **Diagnosis:** The gold standard for tissue diagnosis is the presence of **"Owl’s eye" inclusion bodies** (intranuclear inclusions with a clear halo). * **Treatment:** Intravenous **Ganciclovir** is the drug of choice for CMV pneumonitis; Valganciclovir is used for prophylaxis. * **Monitoring:** CMV viremia is monitored using quantitative PCR or the pp65 antigenemia assay.

Question 1

Which of the following viruses possesses a negative-sense nucleic acid genome?

Accepted Answer

Influenza virus

Answer

Poliovirus

Answer

Rabies virus

Answer

Measles virus

Question 2

Which of the following statements about polio is incorrect?

Accepted Answer

Polio drops are administered only to children younger than 3 years.

Answer

Paralytic polio is the most common form.

Answer

Poliovirus is a single-stranded RNA virus.

Answer

Oral Polio Vaccine (OPV) and Inactivated Polio Vaccine (IPV) are available.

Question 3

Which family do all oncogenic viruses containing RNA belong to?

Accepted Answer

Retroviridae

Answer

Picornaviridae

Answer

Herpesviridae

Answer

None of the above

Question 4

Which of the following investigations is used in the detection and confirmation of HIV?

Accepted Answer

Reverse Transcriptase-PCR

Answer

Polymerase Chain Reaction (PCR)

Answer

Real Time PCR

Answer

Mimic PCR

Question 5

Renal involvement is seen in which of the following infections?

Accepted Answer

Polyoma virus

Answer

Cytomegalovirus

Answer

Human Papilloma virus

Answer

HIV

Question 6

All the following viruses are known to cause Lymphomas except:

Accepted Answer

Japanese Encephalitis virus

Answer

Human T cell leukemia Virus (HTLV-I)

Answer

Epstein Barr Virus (EBV)

Answer

KSHV/ HHV-8

Question 7

Which type of hepatitis is enterically transmitted?

Accepted Answer

Hepatitis E

Answer

Hepatitis C

Answer

Hepatitis D

Answer

Hepatitis F

Question 8

Which cells does HIV selectively infect and destroy?

Accepted Answer

T4 cells

Answer

T3 cells

Answer

K cells

Answer

T10 cells

Question 9

The overall effect of HIV is to gradually impair the immune system by interference with which of the following?

Accepted Answer

Helper T lymphocytes

Answer

Natural killer cells

Answer

Plasma cells

Answer

Macrophages

Question 10

A patient, two months post-renal transplantation, presents with difficulty in breathing. X-ray shows bilateral diffuse interstitial pneumonia. What is the most probable etiologic agent?

Accepted Answer

Cytomegalovirus (CMV)

Answer

Histoplasma capsulatum

Answer

Candida species

Answer

Pneumocystis jirovecii

Virology — MCQs

Virology — MCQs

On this page

Practice by Chapter

Want unlimited practice?