Virology Practice Questions

Q: Which of the following viruses causes an acute febrile rash and produces disease in immunocompetent children but has been associated with transient aplastic crises in persons with sickle cell disease?

Parvovirus B19. **Explanation:** **Parvovirus B19** is the correct answer because it is the causative agent of **Erythema Infectiosum (Fifth Disease)**. In immunocompetent children, it typically presents as an acute febrile illness followed by a characteristic "slapped-cheek" rash. The underlying medical concept involves the virus's tropism for **erythroid progenitor cells**. Parvovirus B19 binds to the **P-antigen** (globoside) on red blood cell precursors and replicates within them, leading to temporary cessation of erythropoiesis. In healthy individuals, this is clinically insignificant. However, in patients with high red cell turnover (e.g., **Sickle Cell Disease**, Hereditary Spherocytosis, or Thalassemia), this pause results in a life-threatening **Transient Aplastic Crisis (TAC)**, characterized by a sudden drop in hemoglobin and a low reticulocyte count. **Why other options are incorrect:** * **Rubella:** Causes "German Measles" with post-auricular lymphadenopathy and a maculopapular rash, but does not affect erythropoiesis or cause aplastic crises. * **Varicella-zoster virus:** Causes chickenpox (vesicular rash) and shingles. It is not associated with aplastic crises in sickle cell patients. * **Measles:** Presents with high fever, Cough, Coryza, Conjunctivitis (3 C's), and Koplik spots. While severe, it does not target erythroid precursors. **High-Yield NEET-PG Pearls:** * **Receptor:** P-antigen (Globoside). * **Fetal Infection:** Can cause **Hydrops Fetalis** due to severe fetal anemia (most common in the second trimester). * **Adults:** Often presents as symmetric polyarthritis (mimicking Rheumatoid Arthritis). * **Diagnosis:** Low reticulocyte count is the hallmark of Parvovirus-induced aplastic crisis.

Q: Varicella-Zoster virus is not associated with which of the following?

Centrifugal rash. **Explanation:** The correct answer is **Centrifugal rash** because Varicella-Zoster Virus (VZV) typically presents with a **centripetal rash**. In medical terminology, a centripetal distribution means the rash is most dense on the trunk (center) and less dense on the extremities (periphery). This is a classic hallmark of Chickenpox. **Analysis of Options:** * **Centrifugal rash (Correct Option):** This is characteristic of **Smallpox**, where the rash is more dense on the face and limbs than on the trunk. Since VZV causes a centripetal rash, this statement is incorrect regarding VZV. * **Latent infection:** VZV follows the pattern of all Herpesviruses by establishing lifelong latency. It remains dormant in the **dorsal root ganglia** or cranial nerve ganglia after the primary infection. * **Chickenpox:** This is the primary clinical manifestation of VZV infection in non-immune individuals (typically children). * **Thrombocytopenia:** While less common, VZV can cause hematological complications, including transient thrombocytopenia and idiopathic thrombocytopenic purpura (ITP), leading to "hemorrhagic chickenpox" in severe cases. **High-Yield Clinical Pearls for NEET-PG:** * **Pleomorphism:** VZV rash is "pleomorphic," meaning lesions at all stages (papules, vesicles, pustules, and crusts) are seen simultaneously in the same area ("starry sky" appearance). * **Dew-drop on a rose petal:** Classic description of the clear VZV vesicle on an erythematous base. * **Reactivation:** Reactivation of latent VZV results in **Herpes Zoster (Shingles)**, characterized by a painful, unilateral vesicular eruption along a specific dermatome. * **Diagnosis:** Tzanck smear shows **multinucleated giant cells** with Cowdry Type A intranuclear inclusion bodies.

Q: A newborn is infected in utero with an enveloped virus containing double-stranded DNA. The child develops petechiae, hepatosplenomegaly, and jaundice. Brain calcifications are detected on computed tomography (CT). With which of the following viruses is the newborn most likely infected?

Cytomegalovirus. **Explanation:** The clinical presentation of petechiae (blueberry muffin rash), hepatosplenomegaly, jaundice, and intracranial calcifications in a neonate is classic for a **Congenital TORCH infection**. **1. Why Cytomegalovirus (CMV) is correct:** CMV is the most common intrauterine infection. It is an **enveloped, double-stranded DNA virus** (a member of the Herpesviridae family). The hallmark finding on CT is **periventricular calcifications** (calcifications lining the ventricles). This distinguishes it from Toxoplasmosis, which typically presents with diffuse cortical calcifications. Other features like microcephaly, sensorineural hearing loss (the most common long-term sequela), and chorioretinitis are also frequently seen. **2. Why the other options are incorrect:** * **Hepatitis B (HBV):** While it is an enveloped DNA virus, neonatal infection usually occurs during delivery (perinatally) rather than in utero. It typically results in a chronic carrier state rather than acute congenital malformations or intracranial calcifications. * **Hepatitis C (HCV) & Hepatitis D (HDV):** These are **RNA viruses** (HCV is Flavivirus; HDV is a defective Deltavirus). They do not cause the classic TORCH constellation of petechiae and brain calcifications. **Clinical Pearls for NEET-PG:** * **CMV:** Periventricular calcifications + Sensorineural hearing loss (SNHL). * **Toxoplasmosis:** Diffuse calcifications + Hydrocephalus + Chorioretinitis. * **Congenital Rubella:** PDA + Cataracts + SNHL (Blueberry muffin rash). * **Diagnosis:** Urine or saliva PCR within the first 3 weeks of life is the gold standard for congenital CMV. * **Treatment:** Intravenous Ganciclovir or oral Valganciclovir is used to reduce the severity of hearing loss and developmental delays.

Q: Epstein-Barr virus (EBV) is responsible for all of the following conditions except?

Hepatoma. **Explanation:** The **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 Hepatoma is the correct answer:** Hepatoma (Hepatocellular Carcinoma) is primarily associated with chronic infections of **Hepatitis B Virus (HBV)** and **Hepatitis C Virus (HCV)**, as well as cirrhosis and aflatoxin exposure. EBV does not play a role in the pathogenesis of primary liver cancer. While EBV can cause transient hepatitis during acute infection (Infectious Mononucleosis), it does not lead to chronic liver malignancy. **Analysis of other options:** * **Nasopharyngeal Carcinoma:** EBV is strongly linked to the undifferentiated type of this tumor, particularly in Southern China and Southeast Asia. It involves the clonal expansion of EBV-infected epithelial cells. * **Burkitt's Lymphoma:** This is a B-cell malignancy highly associated with EBV, especially the "Endemic" (African) form. It characteristically involves the **t(8;14)** translocation of the *c-myc* oncogene. * **Infectious Mononucleosis (Glandular Fever):** This is the primary acute clinical manifestation of EBV, characterized by the triad of fever, pharyngitis, and lymphadenopathy, with the presence of **Atypical Lymphocytes (Downey cells)** in the peripheral smear. **High-Yield Clinical Pearls for NEET-PG:** * **Receptor:** EBV binds to the **CD21** receptor (CR2) on B-cells. * **Diagnosis:** The **Paul-Bunnell Test** (detecting heterophile antibodies) is the classic screening test. * **Other EBV Associations:** Oral Hairy Leukoplakia (in HIV patients), Hodgkin’s Lymphoma (Mixed cellularity type), and Gastric Carcinoma. * **Atypical Lymphocytes:** These are actually activated **CD8+ T-cells** reacting against the infected B-cells.

Q: All of the following statements are true regarding human T cell leukemia virus 1 except?

It has tropism for CD8+ T cells. **Explanation:** Human T-cell Lymphotropic Virus type 1 (HTLV-1) is a complex retrovirus. The correct answer is **Option B** because HTLV-1 primarily exhibits tropism for **CD4+ T cells**, not CD8+ T cells. It uses the GLUT-1 receptor to enter cells, leading to the malignant transformation of helper T cells. **Analysis of Options:** * **Option A (True):** HTLV-1 is the causative agent of **Adult T-cell Leukemia/Lymphoma (ATLL)**. It is also associated with HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). * **Option C (True):** The virus is known for an exceptionally **long latent period**. Most patients are infected during infancy (via breast milk), but clinical leukemia typically manifests 40 to 60 years later. * **Option D (True):** HTLV-1 has low oncogenic penetrance; only **3–5%** of lifelong carriers eventually develop ATLL. The majority of infected individuals remain asymptomatic carriers. **High-Yield Clinical Pearls for NEET-PG:** * **Oncogenesis:** Unlike other retroviruses, HTLV-1 does not carry a host-derived oncogene. Instead, it uses the **Tax gene**, which activates host cell transcription factors (like NF-κB) to promote proliferation and inhibit apoptosis. * **Morphology:** A characteristic finding in the peripheral blood smear of ATLL patients is the presence of **"Flower cells"** (lymphocytes with polylobated nuclei). * **Transmission:** Similar to HIV—via blood transfusion, sexual contact, and vertically (primarily through prolonged breastfeeding). * **Diagnosis:** Screening is done via ELISA; confirmation is via Western Blot or PCR.

Q: Which one of the following viruses is considered a human tumor virus?

Papillomavirus. **Explanation:** The correct answer is **Papillomavirus (HPV)**. Human tumor viruses, or oncogenic viruses, are those capable of inducing neoplastic transformation in host cells. **1. Why Papillomavirus is correct:** High-risk strains of Human Papillomavirus (primarily **HPV 16 and 18**) are strongly associated with cervical, anogenital, and oropharyngeal cancers. The oncogenic potential lies in the viral proteins **E6 and E7**, which inhibit the host’s tumor suppressor proteins **p53 and Rb**, respectively. This leads to uncontrolled cell cycle progression and genomic instability. **2. Why the other options are incorrect:** * **Epstein-Barr virus (EBV):** While EBV is indeed an oncogenic virus (associated with Burkitt lymphoma and Nasopharyngeal carcinoma), in the context of standard multiple-choice questions where only one "best" answer is sought, HPV is often the classic prototype for "human tumor viruses" due to its direct causal link to major epithelial cancers. *Note: If this were a multiple-select question, EBV would also be correct.* * **HIV:** HIV is a lentivirus that causes immunodeficiency. While it increases the risk of cancers (like Kaposi sarcoma) by suppressing the immune system, it is not considered a direct "tumor virus" because it does not transform cells via oncogenes. * **Varicella-zoster virus (VZV):** VZV causes chickenpox and shingles; it has no known oncogenic potential. **High-Yield NEET-PG Pearls:** * **DNA Oncogenic Viruses:** HPV, EBV, Hepatitis B (HBV), Human Herpesvirus 8 (HHV-8), and Merkel Cell Polyomavirus. * **RNA Oncogenic Viruses:** Hepatitis C (HCV) and Human T-cell Lymphotropic Virus-1 (HTLV-1). * **Mechanism Tip:** Remember **"6-53, 7-Rb"** (E6 acts on p53; E7 acts on Rb) to quickly recall HPV pathogenesis.

Q: Inclusion bodies are not seen in which of the following viral infections?

Epstein-Barr virus (EBV). Inclusion bodies are aggregates of viral proteins or nucleic acids within a cell that are visible under a light microscope. While most members of the *Herpesviridae* family produce characteristic inclusions, **Epstein-Barr Virus (EBV)** is a notable exception. ### **Why EBV is the Correct Answer** EBV primarily infects B-lymphocytes and epithelial cells. Unlike other herpesviruses, EBV does not typically produce visible intracellular inclusion bodies during its replicative cycle. Instead, the hallmark of EBV infection (Infectious Mononucleosis) is the presence of **Atypical Lymphocytes (Downey cells)**—which are activated T-cells reacting to the infected B-cells, not viral inclusions themselves. ### **Analysis of Incorrect Options** * **Cytomegalovirus (CMV):** Characterized by large, basophilic intranuclear inclusions surrounded by a clear halo, giving the classic **"Owl’s eye" appearance**. * **Herpes Simplex Virus (HSV):** Produces eosinophilic intranuclear inclusions known as **Cowdry Type A bodies** (also seen in Varicella-Zoster). * **Rabies Virus:** A classic example of intracytoplasmic inclusions called **Negri bodies**, typically found in the Purkinje cells of the cerebellum and pyramidal cells of the hippocampus. ### **High-Yield Clinical Pearls for NEET-PG** * **Intranuclear Inclusions:** DNA viruses (except Poxvirus). Examples: Cowdry A (HSV), Cowdry B (Polio), Owl's eye (CMV). * **Intracytoplasmic Inclusions:** RNA viruses (except Influenza and Measles). Examples: Negri bodies (Rabies), Guarnieri bodies (Smallpox), Henderson-Patterson bodies (Molluscum contagiosum). * **Both Intranuclear & Intracytoplasmic:** Measles (Warthin-Finkeldey cells). * **Mnemonic:** EBV is "Empty" of inclusions but "Extra" (Atypical) lymphocytes.

Q: Which of the following influenza virus types is NOT currently circulating in the world?

H5N1. ### Explanation The correct answer is **C. H5N1**. **1. Why H5N1 is the correct answer:** In the context of human epidemiology, "circulating" refers to viruses that undergo regular, sustained human-to-human transmission (seasonal flu). **H5N1** is an **Avian Influenza (Bird Flu)** virus. While it causes sporadic, severe infections in humans through direct contact with infected poultry, it has **not** yet acquired the ability for sustained human-to-human transmission. Therefore, it is not considered a "circulating" human influenza subtype. **2. Analysis of Incorrect Options:** * **A. H1N1:** This is a subtype of Influenza A. The **A(H1N1)pdm09** strain has been circulating globally since the 2009 pandemic and is a standard component of the seasonal trivalent/quadrivalent vaccines. * **B. H3N2:** This is the other major subtype of Influenza A currently circulating in humans. It often causes more severe seasonal outbreaks in the elderly compared to H1N1. * **C. Influenza B:** Unlike Influenza A, Type B is almost exclusively a human pathogen and does not have subtypes (only lineages like Victoria and Yamagata). It circulates globally every year. **3. High-Yield Clinical Pearls for NEET-PG:** * **Antigenic Shift:** Major genetic changes (reassortment) leading to **Pandemics**. Only occurs in **Influenza A**. * **Antigenic Drift:** Minor point mutations leading to **Epidemics**. Occurs in both **Influenza A and B**. * **Nomenclature:** Hemagglutinin (H) is for attachment; Neuraminidase (N) is for viral release. * **Drug of Choice:** **Oseltamivir** (Neuraminidase inhibitor) is the preferred treatment for both circulating and avian strains. * **Current Human Circulation:** Currently, only **Influenza A (H1N1 and H3N2)** and **Influenza B** circulate regularly among humans.

Q: HPV types 6 and 11 are associated with genital warts. What is their oncogenic risk?

Low. **Explanation:** Human Papillomavirus (HPV) is a double-stranded DNA virus that exhibits tissue tropism for squamous epithelium. HPV types are classified into **Low-risk** and **High-risk** based on their potential to cause malignant transformation (oncogenicity). **Why Option B is Correct:** HPV types **6 and 11** are the most common causes of **Condyloma Acuminatum (Genital Warts)**. These types are classified as **Low-risk** because they primarily cause benign proliferative lesions. While they lead to significant morbidity due to their infectious nature and recurrence, they rarely integrate their DNA into the host genome, which is a prerequisite for malignant progression. **Analysis of Incorrect Options:** * **Option A (High):** High-risk HPV types include **16, 18, 31, 33, and 45**. These are strongly associated with Cervical Intraepithelial Neoplasia (CIN), cervical cancer, and oropharyngeal cancers due to the action of E6 and E7 oncoproteins which inhibit p53 and Rb tumor suppressor proteins, respectively. * **Option C (Nil):** While the risk is low, it is not "nil." In rare clinical scenarios, such as **Buschke-Löwenstein tumors** (giant condyloma acuminatum), these types can show locally aggressive behavior. * **Option D (Variable):** The oncogenic potential is not variable; it is a fixed characteristic of the specific viral genotype. **High-Yield Clinical Pearls for NEET-PG:** * **Most common HPV types in Genital Warts:** 6 and 11. * **Most common HPV types in Cervical Cancer:** 16 and 18. * **HPV 1 & 2:** Associated with Palmoplantar warts (Verruca vulgaris). * **HPV 5 & 8:** Associated with **Epidermodysplasia Verruciformis** and increased risk of Squamous Cell Carcinoma (SCC). * **Histopathology Hallmark:** **Koilocytes** (cells with perinuclear halo and wrinkled "raisinoid" nuclei).

Q: A patient has the following laboratory results for Hepatitis B virus infection: HBsAg Negative, AntiHBsAg Negative, IgM antiHBC Positive, IgG anti HBC Negative. What do these test results indicate?

Window period. ### Explanation The laboratory profile provided indicates the **Window Period** of a Hepatitis B virus (HBV) infection. **1. Why "Window Period" is correct:** The window period is the clinical interval during which **HBsAg** (the first marker to appear) has disappeared from the blood, but **Anti-HBs** (the neutralizing antibody) has not yet reached detectable levels. During this "gap," the only reliable marker of an acute infection is **IgM anti-HBc** (antibody against the core antigen). * **HBsAg (-):** Surface antigen is cleared. * **Anti-HBs (-):** Protective antibodies haven't appeared yet. * **IgM anti-HBc (+):** Confirms a recent/acute infection. **2. Why other options are incorrect:** * **Chronic Infection:** Would be characterized by the persistence of **HBsAg** for >6 months and the presence of **IgG anti-HBc**, not IgM. * **Immunization (Vaccination):** Only **Anti-HBs** would be positive. Since the vaccine contains only the surface protein, core antibodies (Anti-HBc) will always be negative. * **Previous Infection (Recovery):** Both **Anti-HBs** and **IgG anti-HBc** would be positive, indicating the patient has cleared the virus and developed immunity. **3. NEET-PG High-Yield Pearls:** * **IgM anti-HBc** is the **sole marker** of infection during the window period. * **HBsAg** is the first marker to appear (at 4–6 weeks) and indicates infectivity. * **Anti-HBs** signifies immunity (via recovery or vaccination). * **HBeAg** is a marker of active viral replication and high infectivity. * **Anti-HBc** (Total) is the best marker to screen for previous exposure, as it remains positive for life.

Question 1

Which of the following viruses causes an acute febrile rash and produces disease in immunocompetent children but has been associated with transient aplastic crises in persons with sickle cell disease?

Accepted Answer

Parvovirus B19

Answer

Rubella

Answer

Varicella-zoster virus

Answer

Measles

Question 2

Varicella-Zoster virus is not associated with which of the following?

Accepted Answer

Centrifugal rash

Answer

Latent infection

Answer

Chicken pox

Answer

Thrombocytopenia

Question 3

A newborn is infected in utero with an enveloped virus containing double-stranded DNA. The child develops petechiae, hepatosplenomegaly, and jaundice. Brain calcifications are detected on computed tomography (CT). With which of the following viruses is the newborn most likely infected?

Accepted Answer

Cytomegalovirus

Answer

Hepatitis B

Answer

Hepatitis C

Answer

Hepatitis D

Question 4

Epstein-Barr virus (EBV) is responsible for all of the following conditions except?

Accepted Answer

Hepatoma

Answer

Nasopharyngeal carcinoma

Answer

Burkitt's lymphoma

Answer

Infectious mononucleosis

Question 5

All of the following statements are true regarding human T cell leukemia virus 1 except?

Accepted Answer

It has tropism for CD8+ T cells

Answer

It causes adult T cell lymphoma/leukemia

Answer

It has a long latent period of about 40 to 60 years

Answer

Leukemia develops in only 3 to 5% of infected individuals

Question 6

Which one of the following viruses is considered a human tumor virus?

Accepted Answer

Papillomavirus

Answer

Epstein-Barr virus (EBV)

Answer

Human Immunodeficiency Virus (HIV)

Answer

Varicella-zoster virus (VZV)

Question 7

Inclusion bodies are not seen in which of the following viral infections?

Accepted Answer

Epstein-Barr virus (EBV)

Answer

Cytomegalovirus (CMV)

Answer

Herpes simplex virus (HSV)

Answer

Rabies virus

Question 8

Which of the following influenza virus types is NOT currently circulating in the world?

Accepted Answer

H5N1

Answer

H1N1

Answer

H3N2

Answer

Influenza B virus

Question 9

HPV types 6 and 11 are associated with genital warts. What is their oncogenic risk?

Accepted Answer

Low

Answer

High

Answer

Nil

Answer

Variable

Question 10

A patient has the following laboratory results for Hepatitis B virus infection: HBsAg Negative, AntiHBsAg Negative, IgM antiHBC Positive, IgG anti HBC Negative. What do these test results indicate?

Accepted Answer

Window period

Answer

Chronic infection

Answer

Immunization

Answer

Previous infection

Virology — MCQs

Virology — MCQs

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