Virology Practice Questions

Q: Verrucous carcinoma of the penis is caused by which type of Human Papillomavirus (HPV)?

HPV 11. **Explanation:** **Verrucous carcinoma of the penis**, also known as **Buschke-Löwenstein tumor**, is a rare, well-differentiated variant of squamous cell carcinoma. Unlike typical penile cancer, it is locally aggressive and can grow to a massive size but rarely metastasizes. 1. **Why HPV 11 is correct:** Verrucous carcinoma is strongly associated with **low-risk HPV types 6 and 11**. These types are traditionally linked to benign genital warts (Condyloma acuminata). Verrucous carcinoma is often considered a giant, exophytic version of these warts that exhibits local invasion but lacks the cytological malignancy seen in high-risk infections. 2. **Why the other options are incorrect:** * **HPV 16 & 18:** These are **high-risk HPV types**. They are the primary causative agents for typical (non-verrucous) Squamous Cell Carcinoma of the penis, as well as cervical and anal cancers. They produce E6 and E7 oncoproteins which inhibit p53 and Rb tumor suppressor genes. * **HPV 32:** This type is specifically associated with **Heck’s disease** (Focal Epithelial Hyperplasia), which manifests as multiple white-to-pink papules in the oral cavity, not penile malignancies. **High-Yield Clinical Pearls for NEET-PG:** * **Morphology:** Presents as a "cauliflower-like" fungating mass. * **Histology:** Characterized by a "pushing" deep margin rather than an infiltrating one. It lacks koilocytosis (which is seen in condylomas). * **Management:** Wide local excision is the treatment of choice. **Radiotherapy is contraindicated** as it may trigger anaplastic transformation and increase metastatic potential. * **Prognosis:** Excellent if surgically excised, due to the low risk of lymph node involvement.

Q: All of the following are true regarding R5 strain of HIV except?

Predominates in late stages of HIV. ### Explanation The HIV-1 virus enters host cells by binding to the CD4 receptor and a specific co-receptor (chemokine receptor). Based on co-receptor usage, HIV strains are classified into **R5 (M-tropic)** and **X4 (T-tropic)**. **Why Option B is the Correct Answer (The False Statement):** R5 strains utilize the **CCR5** co-receptor and are the **predominant strains during the early stages** of infection (acute phase and asymptomatic period). They are responsible for the initial establishment of infection. In contrast, **X4 strains** (which use the CXCR4 co-receptor) typically emerge in the **late stages** of the disease, correlating with a rapid decline in CD4+ T-cell counts and progression to AIDS. **Analysis of Other Options:** * **Option A:** R5 strains specifically utilize the **CCR5** co-receptor, which is found on macrophages, dendritic cells, and memory T-cells. * **Option C:** R5 strains are the primary strains involved in **mucosal transmission**. They are more efficiently transmitted sexually compared to X4 strains, even if the donor has both types (the "gatekeeper" effect). * **Option D:** Microglial cells in the central nervous system express CD4 and CCR5; therefore, R5 strains are the primary neurotropic variants that infect these cells, potentially leading to HIV-associated neurocognitive disorders. ### High-Yield Pearls for NEET-PG: * **Maraviroc:** A CCR5 antagonist (entry inhibitor) that is only effective against R5-tropic HIV. A "Tropism Assay" must be performed before starting this drug. * **CCR5-Δ32 Mutation:** A 32-base pair deletion in the CCR5 gene. Individuals homozygous for this mutation are virtually resistant to R5-tropic HIV infection. * **Mnemonic:** **R5** = **M**acrophage-tropic (Early); **X4** = **T**-cell-tropic (Late).

Q: Which type of Human Papillomavirus (HPV) is considered low risk?

Type-6. ### Explanation Human Papillomavirus (HPV) is a double-stranded DNA virus that infects epithelial cells. It is categorized into **Low-risk** and **High-risk** types based on its association with malignancy. **Why Type-6 is Correct:** **HPV Type-6** (along with Type-11) is classified as **Low-risk**. These types primarily cause benign proliferative lesions such as **Condyloma acuminatum** (anogenital warts) and **Laryngeal papillomatosis**. They rarely integrate their DNA into the host genome, meaning they do not typically lead to squamous cell carcinoma. **Analysis of Incorrect Options:** * **Type-16 (Option A):** This is the most oncogenic high-risk type globally. It is responsible for approximately 50-60% of cervical cancers and is also strongly associated with oropharyngeal and anal cancers. * **Type-18 (Option C):** The second most common high-risk type, accounting for about 10-15% of cervical cancers. It is particularly associated with cervical **adenocarcinoma**. * **Type-31 (Option D):** A high-risk type that, along with types 33, 45, 52, and 58, is a significant contributor to cervical intraepithelial neoplasia (CIN) and invasive cancer. **High-Yield Clinical Pearls for NEET-PG:** * **Oncogenesis:** High-risk types (16, 18) produce oncoproteins **E6** (inhibits **p53**) and **E7** (inhibits **pRb**), leading to uncontrolled cell cycle progression. * **Cytopathology:** The hallmark of HPV infection on a Pap smear is the **Koilocyte** (a cell with a perinuclear halo and wrinkled "raisinoid" nucleus). * **Vaccination:** The **9-valent vaccine (Gardasil 9)** covers low-risk types 6, 11 and high-risk types 16, 18, 31, 33, 45, 52, and 58.

Q: Human immunodeficiency virus (HIV) has been isolated from many body fluids. Which of the following is a major source of transmission?

Semen. **Explanation:** The transmission of Human Immunodeficiency Virus (HIV) depends on the **viral load** (concentration of the virus) within a specific body fluid and the presence of infected CD4+ T-cells or macrophages. **Why Semen is Correct:** HIV is found in high concentrations in **semen** and **vaginal secretions**, both as free virus particles and within infected mononuclear cells. Sexual transmission (predominantly via semen) remains the most common mode of HIV spread globally. Other major high-risk fluids include blood, breast milk, and cerebrospinal fluid. **Why Other Options are Incorrect:** * **Tears, Sweat, and Urine:** While HIV has been isolated in trace amounts from these fluids in research settings, the viral concentration is **insignificantly low** to pose a risk of transmission. These are considered non-infectious fluids unless they are visibly contaminated with blood. **High-Yield Clinical Pearls for NEET-PG:** * **Risk of Transmission:** The highest risk of transmission per act is via **blood transfusion** (approx. 90%), followed by vertical transmission (mother-to-child) and receptive anal intercourse. * **Window Period:** The time between infection and the appearance of detectable antibodies (usually 2–8 weeks). During this time, the person is highly infectious despite a negative ELISA. * **Target Cells:** HIV primarily infects cells expressing the **CD4 receptor** and co-receptors **CCR5** (macrophages/early infection) or **CXCR4** (T-cells/late infection). * **Screening vs. Confirmation:** ELISA is the standard screening test (high sensitivity), while **Western Blot** was traditionally the confirmatory test (high specificity). However, current NACO guidelines emphasize the use of three different rapid antibody tests for diagnosis.

Q: Which geographical region is predominantly associated with HIV C subtype?

India. **Explanation:** The distribution of Human Immunodeficiency Virus (HIV) is characterized by significant genetic diversity, with **HIV-1 Group M** being responsible for the global pandemic. This group is further divided into several subtypes (clades). **1. Why India is Correct:** **Subtype C** is the most prevalent subtype of HIV-1 worldwide, accounting for nearly half of all global infections. It is the predominant strain in **India**, South Africa, and Ethiopia. In India, Subtype C is responsible for over 90% of HIV infections, making it a high-yield fact for community medicine and microbiology. **2. Analysis of Incorrect Options:** * **Europe and America (Options B & C):** These regions are predominantly associated with **Subtype B**. Most early research and clinical trials were conducted on this subtype, although other subtypes are now increasing due to migration. * **Thailand (Option D):** Southeast Asia, particularly Thailand, is uniquely associated with the **CRF01_AE** (a circulating recombinant form) and Subtype B. **High-Yield Clinical Pearls for NEET-PG:** * **Most common HIV type globally:** HIV-1. * **Most common HIV-1 Subtype globally and in India:** Subtype C. * **HIV-2 prevalence:** Primarily restricted to West Africa; in India, it is most commonly seen in Maharashtra and parts of Southern India. * **Transmission:** While Subtype B is often associated with MSM (men who have sex with men) in Western countries, Subtype C in India is primarily spread through **heterosexual transmission**. * **Diagnosis:** The "Window Period" for modern 4th generation ELISA (p24 antigen + antibody) is typically 14–21 days.

Q: All of the following are true about Ebola virus except?

Belongs to the Filoviridae family. **Explanation:** The question asks for the "Except" statement, but based on virological facts, **Option B is actually a true statement.** Ebola virus indeed belongs to the **Filoviridae** family. In the context of this question, if Option B is marked as the "correct answer" (the false statement), it is likely a typographical error in the question source, as all four options provided are technically correct descriptions of the Ebola virus. **Breakdown of Options:** * **Option A (True):** The incubation period for Ebola Virus Disease (EVD) typically ranges from **2 to 21 days**. This is a critical timeframe for quarantine and monitoring of suspected cases. * **Option B (True):** Ebola, along with Marburg virus, belongs to the **Filoviridae** family. They are enveloped, non-segmented, negative-sense RNA viruses. * **Option C (True):** Under Electron Microscopy (EM), Filoviruses exhibit a highly pleomorphic, **thread-like (filamentous)** appearance. They often fold into structures resembling a **'shepherd’s crook'**, the letter '6', or a 'U'. * **Option D (True):** **RT-PCR** (Reverse Transcription Polymerase Chain Reaction) is the **investigation of choice** for acute diagnosis, as it can detect the viral RNA in blood or body fluids shortly after symptom onset. **High-Yield Clinical Pearls for NEET-PG:** * **Transmission:** Primarily through direct contact with infected blood, secretions, or organs (including fruit bats, the natural reservoir). * **Pathogenesis:** Causes severe hemorrhagic fever by infecting endothelial cells and causing a "cytokine storm." * **Biosafety Level:** Ebola requires **BSL-4** containment (the highest level). * **Vaccine:** The **rVSV-ZEBOV** vaccine is used for prevention during outbreaks.

Q: A 24-hour history of fever in an infant is followed by the appearance of a maculopapular rash and erythema on the face. What other condition can be caused by the organism responsible for these symptoms?

Pure red cell aplasia. **Explanation:** The clinical presentation of fever followed by a facial maculopapular rash (classically described as a **"slapped-cheek" appearance**) in an infant is diagnostic of **Erythema Infectiosum (Fifth Disease)**. This condition is caused by **Parvovirus B19**, a small, non-enveloped DNA virus. **Why the correct answer is right:** Parvovirus B19 specifically targets and infects **erythroid progenitor cells** in the bone marrow by binding to the **P-antigen** (globoside). In healthy individuals, this causes a transient drop in hemoglobin. However, in patients with underlying hemolytic anemias (like Sickle Cell Disease) or immunocompromised states, it can lead to a cessation of red blood cell production, resulting in a **Transient Aplastic Crisis** or **Pure Red Cell Aplasia (PRCA)**. **Analysis of Incorrect Options:** * **A & D (Leukemias):** Acute myeloid leukemia and Hairy cell leukemia are neoplastic proliferations of leukocytes. Parvovirus B19 is not oncogenic and does not cause these malignancies. * **B (Cytomegalovirus):** While CMV is a common viral infection in infants, it typically presents with hepatosplenomegaly, jaundice, or mononucleosis-like symptoms, rather than the classic "slapped-cheek" rash. **High-Yield NEET-PG Pearls:** * **Receptor:** P-antigen (Globoside) on RBCs. * **Pregnancy:** Infection during pregnancy can lead to **Hydrops Fetalis** due to severe fetal anemia and high-output heart failure. * **Adults:** Often presents as symmetrical **arthralgia/arthritis** (mimicking Rheumatoid Arthritis). * **Morphology:** Look for **"Giant Pronormoblasts"** with viral inclusions in the bone marrow.

Q: Which virus is the leading cause of the croup syndrome in young children and, when infecting mammalian cells in culture, will hemadsorb red blood cells?

Parainfluenza virus. **Explanation:** The correct answer is **Parainfluenza virus (PIV)**. This virus belongs to the *Paramyxoviridae* family and is the most common cause of **Croup (Laryngotracheobronchitis)** in children aged 6 months to 3 years. **Why it is correct:** 1. **Clinical Presentation:** PIV (specifically Type 1 and 2) causes subglottic edema, leading to the classic triad of barking cough, inspiratory stridor, and hoarseness. 2. **Hemadsorption:** PIV possesses a **Hemagglutinin-Neuraminidase (HN) protein** on its envelope. When the virus infects a cell culture, these viral proteins are expressed on the host cell membrane. If red blood cells (RBCs) are added to the culture, they adhere to the surface of the infected cells—a phenomenon known as **hemadsorption**. This is a key diagnostic laboratory feature for Paramyxoviruses and Orthomyxoviruses. **Why other options are incorrect:** * **Group B Coxsackievirus:** Primarily associated with pleurodynia (Bornholm disease), myocarditis, and herpangina; it does not cause croup or exhibit hemadsorption. * **Rotavirus:** The leading cause of severe dehydrating diarrhea in infants; it is a non-enveloped Reovirus. * **Adenovirus:** While it can cause respiratory infections (pharyngoconjunctival fever), it is a DNA virus that does not typically cause croup and does not hemadsorb. **High-Yield NEET-PG Pearls:** * **Steeple Sign:** X-ray finding in Croup showing subglottic narrowing. * **Genome:** PIV is a pleomorphic, enveloped, negative-sense ssRNA virus. * **Syncytia formation:** Like other Paramyxoviruses, PIV induces cell-to-cell fusion (multinucleated giant cells) via its Fusion (F) protein.

Q: Which of the following cells are affected by HIV?

T helper cells and macrophages. **Explanation:** The Human Immunodeficiency Virus (HIV) primarily targets cells that express the **CD4 receptor** on their surface. The HIV envelope glycoprotein **gp120** binds specifically to the CD4 molecule to initiate entry. * **Why Option B is Correct:** While **T-helper (CD4+) lymphocytes** are the primary targets and their depletion leads to profound immunosuppression, HIV also infects **macrophages, monocytes, and dendritic cells**. These cells also express CD4 receptors (albeit at lower levels than T-cells) and various co-receptors (CCR5). Macrophages are particularly important as they are resistant to the cytopathic effects of the virus, acting as a **reservoir** for HIV and transporting it to the central nervous system (CNS). * **Why other options are incorrect:** * **Option A:** HIV does not *only* affect T-helper cells; excluding macrophages ignores a critical part of the viral pathogenesis and its persistence in the body. * **Option C & D:** Natural Killer (NK) cells and B lymphocytes do not typically express the CD4 receptor. While B-cell function is often deranged in AIDS (leading to polyclonal hypergammaglobulinemia), this is a secondary effect of the loss of T-helper cell regulation, not a result of direct viral infection. **High-Yield Clinical Pearls for NEET-PG:** * **Co-receptors:** HIV requires co-receptors for entry: **CCR5** (predominant in early infection/macrophage-tropic) and **CXCR4** (seen in late-stage infection/T-cell-tropic). * **Homozygous mutation of CCR5 (CCR5-Δ32)** provides immunity against HIV infection. * **Follicular Dendritic Cells** in the lymph nodes serve as major reservoirs for HIV. * **Microglial cells** are the primary targets of HIV in the brain, leading to HIV-associated dementia.

Question 1

Verrucous carcinoma of the penis is caused by which type of Human Papillomavirus (HPV)?

Accepted Answer

HPV 11

Answer

HPV 16

Answer

HPV 18

Answer

HPV 32

Question 2

All of the following are true regarding R5 strain of HIV except?

Accepted Answer

Predominates in late stages of HIV

Answer

Utilizes CCR5 co-receptor

Answer

Transmits HIV efficiently

Answer

Infects microglial cells

Question 3

Which type of Human Papillomavirus (HPV) is considered low risk?

Accepted Answer

Type-6

Answer

Type-16

Answer

Type-18

Answer

Type-31

Question 4

Human immunodeficiency virus (HIV) has been isolated from many body fluids. Which of the following is a major source of transmission?

Accepted Answer

Semen

Answer

Tears

Answer

Sweat

Answer

Urine

Question 5

Which of the following statements regarding viral replication and diseases is FALSE?

Accepted Answer

DNA viruses include Adenovirus, Human papilloma virus, Parvovirus B-19, BK and JC polyomavirus, and Poliovirus.

Answer

The general stages of viral replication include penetration, uncoating, macromolecular synthesis (transcription, protein synthesis, replication), assembly, and release by budding and lysis.

Answer

Ganciclovir is used for Cytomegalovirus (CMV) infections and acts on viral DNA.

Answer

Viruses that can cause congenital and neonatal disease include HSV-2, Echovirus, CMV, Parvovirus B19, VZV, HIV, and Hepatitis viruses.

Question 6

Which geographical region is predominantly associated with HIV C subtype?

Accepted Answer

India

Answer

Europe

Answer

America

Answer

Thailand

Question 7

All of the following are true about Ebola virus except?

Accepted Answer

Belongs to the Filoviridae family

Answer

Incubation period is 2-21 days

Answer

Under electron microscopy, virions show a characteristic 'shepherd's crook' or 'thread-like' morphology

Answer

Investigation of choice is RT-PCR

Question 8

A 24-hour history of fever in an infant is followed by the appearance of a maculopapular rash and erythema on the face. What other condition can be caused by the organism responsible for these symptoms?

Accepted Answer

Pure red cell aplasia

Answer

Acute myeloid leukemia

Answer

Cytomegalovirus infection

Answer

Hairy cell leukemia

Question 9

Which virus is the leading cause of the croup syndrome in young children and, when infecting mammalian cells in culture, will hemadsorb red blood cells?

Accepted Answer

Parainfluenza virus

Answer

Group B coxsackievirus

Answer

Rotavirus

Answer

Adenovirus

Question 10

Which of the following cells are affected by HIV?

Accepted Answer

T helper cells and macrophages

Answer

Only T helper cells

Answer

NK cells

Answer

B lymphocytes

Virology — MCQs

Virology — MCQs

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