Virology Practice Questions

Q: What is the causative agent for a lesion on the penis?

Human Papillomavirus (HPV). ***Human Papillomavirus (HPV)*** - HPV, particularly types 6 and 11, causes **condyloma acuminata** (genital warts), presenting as **cauliflower-like lesions** on the penis and other genital areas. - These lesions are **painless**, **flesh-colored**, and can appear as single or multiple growths, making HPV the most common cause of benign penile lesions. *Treponema pallidum* - Causes **primary syphilis** with a **painless, indurated chancre** that appears as a single, well-demarcated ulcer rather than warty growths. - The chancre has **rolled edges** and a **clean base**, distinctly different from the papillomatous appearance of condyloma acuminata. *Epstein-Barr Virus (EBV)* - Primarily causes **infectious mononucleosis** with symptoms like fever, sore throat, and **lymphadenopathy**. - Does **not typically cause penile lesions** and is associated with **nasopharyngeal carcinoma** and **Burkitt lymphoma**, not genital manifestations. *Human Herpesvirus 6 (HHV-6)* - Causes **roseola infantum** (sixth disease) in children, presenting with high fever followed by a **maculopapular rash** on the trunk. - Does **not cause penile lesions** and is not associated with sexually transmitted genital manifestations.

Q: What change does HPV cause in the cervical epithelium?

Immortalization of epithelial cells. **Explanation:** Human Papillomavirus (HPV), particularly high-risk types 16 and 18, is a potent oncogenic virus. The core mechanism behind its pathogenicity lies in the integration of the viral genome into the host cell DNA, leading to the overexpression of two key oncoproteins: **E6 and E7**. * **E6** binds to and degrades the **p53** tumor suppressor protein (via ubiquitin ligase). * **E7** binds to and inactivates the **Retinoblastoma (Rb)** protein, releasing the E2F transcription factor. The loss of these "guardians of the genome" prevents cell cycle arrest and DNA repair, leading to uncontrolled proliferation and the **immortalization of epithelial cells**. This transformation is the hallmark of progression from dysplasia to cervical carcinoma. **Analysis of Incorrect Options:** * **A & B (Apoptosis/Necrosis):** HPV aims to keep the host cell alive to utilize its replication machinery. E6 specifically inhibits apoptosis by degrading p53; therefore, the virus prevents rather than induces cell death. * **D (Stimulation of telomerase):** While E6 *can* indirectly activate telomerase to maintain telomere length, "Immortalization" (Option C) is the broader, more definitive pathological description of the change HPV causes in the cervical epithelium. In the context of NEET-PG, immortalization via p53/Rb inhibition is the primary recognized mechanism. **High-Yield Facts for NEET-PG:** * **Koilocytes:** Pathognomonic finding in HPV (cells with perinuclear halo and wrinkled "raisinoid" nuclei). * **Vaccination:** Quadrivalent vaccine (Gardasil) targets types 6, 11, 16, and 18. * **Screening:** Pap smear looks for cytological changes; HPV DNA testing is more sensitive for high-risk types.

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

Has a live attenuated vaccine. **Explanation:** The correct answer is **B**, as there is currently **no vaccine available** for Hepatitis C Virus (HCV). Developing a vaccine is challenging due to the virus's high genetic variability and the existence of multiple genotypes. * **Why Option B is correct:** Unlike Hepatitis A (inactivated) or Hepatitis B (recombinant), HCV lacks a vaccine. Prevention relies on screening blood products and harm reduction. * **Why Option A is incorrect:** HCV is the leading cause of chronic viral hepatitis worldwide. Approximately 75–85% of individuals infected with HCV develop a **chronic infection**, which is a much higher rate than Hepatitis B (where <5% of adults become chronic). * **Why Option C is incorrect:** HCV is primarily a **parenterally transmitted** virus. Before universal screening of blood donors, blood transfusion was a major route of transmission. Today, IV drug use is the most common risk factor. * **Why Option D is incorrect:** HCV is a member of the **Flaviviridae** family (genus *Hepacivirus*). It is an enveloped, positive-sense, single-stranded RNA virus. **High-Yield Clinical Pearls for NEET-PG:** * **"HCV is for Chronic":** It is the most common cause of post-transfusion hepatitis and a leading indication for liver transplantation. * **Diagnosis:** Screening is done via **Anti-HCV antibodies** (ELISA), but confirmation of active infection requires **HCV-RNA** (PCR). * **Treatment:** Chronic HCV is now highly curable using **Direct-Acting Antivirals (DAAs)** like Sofosbuvir. * **Extrahepatic manifestations:** Associated with Mixed Cryoglobulinemia, Membranoproliferative Glomerulonephritis (MPGN), and Porphyria Cutanea Tarda.

Q: What is the most common cause of acute aseptic meningitis in children?

Enterovirus. **Explanation:** **Enteroviruses** (specifically Coxsackievirus A and B, and Echoviruses) are the most common cause of acute aseptic meningitis in children, accounting for **>80-90% of cases** where a pathogen is identified. They typically follow a seasonal pattern, peaking in late summer and early autumn. The virus enters via the fecal-oral or respiratory route, replicates in the lymphoid tissue of the GI tract, and spreads hematogenously to the central nervous system. **Analysis of Incorrect Options:** * **Arboviruses (Option A):** While significant causes of meningoencephalitis (e.g., Japanese Encephalitis in specific endemic regions), they are less common overall than Enteroviruses and often present with more severe parenchymal involvement (encephalitis). * **Respiratory Syncytial Virus (Option B):** RSV is a primary cause of lower respiratory tract infections (bronchiolitis and pneumonia) in infants. It rarely involves the CNS. * **Herpes Family (Option D):** HSV-2 is a common cause of aseptic meningitis in adults, and HSV-1 is the leading cause of sporadic fatal encephalitis. While they cause CNS infections in neonates and children, they do not match the high prevalence of Enteroviruses. **High-Yield Clinical Pearls for NEET-PG:** * **CSF Findings in Aseptic Meningitis:** Normal glucose, normal to slightly elevated protein, and lymphocytic pleocytosis (though neutrophils may predominate in the first 24 hours). * **Diagnosis:** PCR of the CSF is the gold standard for Enteroviral meningitis due to its high sensitivity. * **Prognosis:** Generally excellent with supportive care, unlike bacterial meningitis. * **Hand-Foot-Mouth Disease:** Often co-exists or precedes meningitis caused by Coxsackievirus A16 or Enterovirus 71.

Q: Which of the following hepatitis viruses is non-enveloped?

Hepatitis A virus (HAV). **Explanation:** The classification of hepatitis viruses into enveloped or non-enveloped is a high-yield concept in medical microbiology. Hepatitis viruses that are transmitted via the **fecal-oral route** are typically **non-enveloped**, as they must survive the harsh acidic environment of the gastrointestinal tract. Conversely, those transmitted via blood or body fluids are generally **enveloped**. **1. Why Hepatitis A (HAV) is correct:** HAV belongs to the *Picornaviridae* family. It is a small, **non-enveloped**, single-stranded RNA virus. Its lack of an envelope makes it highly resistant to degradation by bile and gastric acid, facilitating its transmission through contaminated food and water. **Hepatitis E virus (HEV)** is the only other major hepatitis virus that is also non-enveloped. **2. Why the other options are incorrect:** * **Hepatitis B (HBV):** A member of the *Hepadnaviridae* family. It is a DNA virus that possesses a complex lipid envelope containing the HBsAg (surface antigen). * **Hepatitis C (HCV):** A member of the *Flaviviridae* family. It is an enveloped RNA virus. The envelope makes it fragile and dependent on direct blood-to-blood contact for transmission. * **Hepatitis D (HDV):** Known as a "defective" virus, it requires the HBsAg envelope from HBV to become infectious. Thus, it is an enveloped virus. **Clinical Pearls for NEET-PG:** * **Mnemonic:** "The **Vowels** (A and E) go through the **Bowel** (Fecal-oral) and have **No** (Non-enveloped) shell." * **HAV** is the most common cause of acute viral hepatitis in children worldwide. * **HEV** is associated with high mortality (up to 20%) in pregnant women, particularly in the third trimester. * All hepatitis viruses are RNA viruses except **HBV**, which is a **DNA virus**.

Q: Human metapneumovirus is structurally similar to which of the following viruses?

Respiratory syncytial virus. ### Explanation **Correct Answer: B. Respiratory syncytial virus (RSV)** **Why it is correct:** Human metapneumovirus (hMPV) and Respiratory syncytial virus (RSV) both belong to the family **Paramyxoviridae**. Specifically, hMPV is a member of the genus *Metapneumovirus*, while RSV belongs to the genus *Orthopneumovirus* (formerly both were in the subfamily *Pneumovirinae*). Structurally, both are pleomorphic, enveloped viruses containing a **non-segmented, negative-sense, single-stranded RNA** genome. They share similar clinical presentations, primarily causing bronchiolitis and pneumonia in infants and the elderly. **Why the other options are incorrect:** * **A. Influenza virus:** Belongs to the **Orthomyxoviridae** family. Its primary structural difference is a **segmented genome** (8 segments), which allows for antigenic shift. * **C. Measles virus:** While it is in the Paramyxoviridae family (genus *Morbillivirus*), it is structurally and clinically distinct from the pneumoviruses. Measles is characterized by systemic infection, Koplik spots, and a maculopapular rash, rather than being restricted primarily to the respiratory epithelium. * **D. Rubella virus:** Belongs to the **Matonaviridae** family (formerly Togaviridae). It is a positive-sense, single-stranded RNA virus and is much smaller than the paramyxoviruses. **High-Yield Clinical Pearls for NEET-PG:** * **hMPV Discovery:** It was first identified in 2001; it is the second most common cause of lower respiratory tract infections in children after RSV. * **Surface Proteins:** Unlike other Paramyxoviruses, hMPV and RSV **lack Hemagglutinin (H) and Neuraminidase (N)** activities on their attachment proteins. * **Diagnosis:** RT-PCR is the gold standard for hMPV as it is difficult to isolate in standard cell cultures. * **Seasonality:** Similar to RSV, hMPV peaks during late winter and spring.

Q: What is the most important marker in diagnosing acute Hepatitis B?

IgM Anti-HBc. **Explanation:** The diagnosis of acute Hepatitis B relies on identifying markers that appear during the initial phase of infection. **IgM Anti-HBc** is the most important marker because it is the first antibody to appear and is specifically indicative of a **recent/acute infection** (typically within the last 6 months). **Why IgM Anti-HBc is the correct answer:** It is the only reliable marker during the **"Window Period"**—the interval when HBsAg has disappeared but Anti-HBs has not yet become detectable. Its presence confirms acute replication even when other surface markers are negative. **Analysis of incorrect options:** * **IgG Anti-HBc:** This indicates a past infection or chronic state. It persists for life and does not differentiate between an ongoing chronic infection and a recovered state. * **Anti-HBs:** This antibody signifies **immunity**, either through recovery from a natural infection or via vaccination. It appears only after the acute phase has resolved. * **HBsAg:** While it is the first marker to appear in the blood (indicating the presence of the virus), it cannot distinguish between an **acute** infection and a **chronic carrier** state. **High-Yield Clinical Pearls for NEET-PG:** * **First marker to appear:** HBsAg. * **First antibody to appear:** IgM Anti-HBc. * **Marker of Infectivity:** HBeAg (indicates high viral replication). * **Marker of Recovery/Immunity:** Anti-HBs. * **Vaccination Profile:** Only Anti-HBs is positive; all other markers (including Anti-HBc) are negative. * **Window Period Marker:** IgM Anti-HBc is the sole diagnostic tool.

Q: Mad Cow disease (Spongiform disease) occurs due to which of the following?

Prions (specifically, abnormal prion proteins, not viruses). **Explanation:** **Mad Cow Disease**, medically known as **Bovine Spongiform Encephalopathy (BSE)**, is caused by **Prions**. Prions are unique infectious agents because they lack nucleic acids (DNA or RNA). They are misfolded proteins ($PrP^{Sc}$) that induce normal cellular prion proteins ($PrP^C$) in the host’s brain to also misfold into the pathological isoform. This leads to neuronal loss and a characteristic "spongiform" (sponge-like) appearance of the brain tissue. **Analysis of Options:** * **Option A (Correct):** Prions are the established causative agents of Transmissible Spongiform Encephalopathies (TSEs) like BSE in cattle and Creutzfeldt-Jakob Disease (CJD) in humans. * **Option B (Arena Virus):** These are RNA viruses (e.g., Lassa fever, LCMV) that typically cause hemorrhagic fevers or meningitis, not spongiform degeneration. * **Option C (Kuru Virus):** This is a **misnomer**. While Kuru is a spongiform disease, it is caused by **prions** (transmitted via ritualistic cannibalism), not a virus. * **Option D (Parvo Virus):** B19 virus is a DNA virus known for causing Erythema Infectiosum (Fifth disease), aplastic crisis, and hydrops fetalis. **High-Yield Clinical Pearls for NEET-PG:** * **Resistance:** Prions are highly resistant to standard sterilization methods (autoclaving, UV, formalin). Recommended decontamination involves **1N NaOH** or **Sodium Hypochlorite** for 1 hour. * **Human Variant:** Consumption of BSE-infected beef is linked to **variant CJD (vCJD)** in humans. * **Diagnosis:** Characterized by the absence of an inflammatory response and the presence of **14-3-3 protein** in the CSF. * **Amyloid Plaques:** Histology shows extracellular accumulation of prion protein aggregates.

Q: Epstein-Barr virus (EBV) is associated with which of the following conditions, EXCEPT?

Verrucous lymphoma. ### **Explanation** The correct answer is **C. Verrucous lymphoma**. **1. Why Verrucous Lymphoma is the correct answer:** There is no clinical entity known as "Verrucous lymphoma." The term "Verrucous" typically refers to **Verrucous Carcinoma** (a low-grade variant of squamous cell carcinoma), which is primarily associated with **Human Papillomavirus (HPV)** types 6 and 11, not EBV. Therefore, it is the "except" option in this list. **2. Analysis of Incorrect Options (EBV-associated conditions):** * **Nasopharyngeal Carcinoma (Option A):** EBV has a strong causal link with the undifferentiated type (Type III) of nasopharyngeal carcinoma, particularly prevalent in Southern China and Southeast Asia. * **Burkitt’s Lymphoma (Option B):** EBV is associated with the **Endemic (African)** form of Burkitt’s lymphoma, characterized by the $t(8;14)$ translocation involving the *c-myc* oncogene. * **Hodgkin’s Lymphoma (Option D):** EBV is found in approximately 40–50% of Hodgkin’s cases, most commonly the **Mixed Cellularity** subtype. **3. NEET-PG High-Yield Clinical Pearls:** * **Virus Family:** EBV is Human Herpesvirus 4 (HHV-4), a gamma-herpesvirus. * **Cell Tropism:** It infects B-cells via the **CD21 receptor** (also known as CR2). * **Diagnosis:** Look for **Atypical Lymphocytes (Downey cells)** on peripheral smear and a positive **Monospot test** (Heterophile antibodies). * **Other EBV Associations:** * Infectious Mononucleosis (Glandular fever). * Oral Hairy Leukoplakia (seen in HIV/AIDS). * Post-transplant lymphoproliferative disorder (PTLD). * Gastric Carcinoma (subset of cases).

Q: A 3-month-old child was admitted with pneumonia. The microscopy shows the following image. Choose the correct organism.

Influenza. ***Influenza*** - The image displays a virus with two key surface glycoproteins: **Hemagglutinin (HA)** and **Neuraminidase (NA)**. These proteins are the defining structural features of the Influenza virus and are crucial for its entry into and exit from host cells. - Influenza virus is a well-known cause of respiratory illnesses, including severe **pneumonia**, particularly in high-risk groups such as infants, the elderly, and immunocompromised individuals. *Rotavirus* - Rotavirus is the leading cause of severe **gastroenteritis** (diarrhea and vomiting) in infants and young children; it is not a primary cause of pneumonia. - It is a **non-enveloped** virus with a distinct wheel-like appearance (hence the name "rota"), which is structurally different from the enveloped virus shown in the diagram. *Hepatitis virus* - Hepatitis viruses (A, B, C, etc.) are hepatotropic, meaning they primarily infect and cause inflammation of the **liver (hepatitis)**, and are not associated with respiratory infections like pneumonia. - Their viral structures and surface antigens are different; for example, Hepatitis B virus has **HBsAg** on its surface, not HA and NA. *Respiratory syncytial virus* - While RSV is a very common cause of **pneumonia** and **bronchiolitis** in infants, its viral structure differs from the one depicted. - RSV belongs to the *Paramyxoviridae* family and has **Fusion (F)** and **Attachment (G)** proteins on its surface, not Hemagglutinin and Neuraminidase.

Question 1

What is the causative agent for a lesion on the penis?

Accepted Answer

Human Papillomavirus (HPV)

Answer

Treponema pallidum

Answer

Epstein-Barr Virus (EBV)

Answer

Human Herpesvirus 6 (HHV-6)

Question 2

What change does HPV cause in the cervical epithelium?

Accepted Answer

Immortalization of epithelial cells

Answer

Induction of apoptosis

Answer

Induction of necrosis

Answer

Stimulation of telomerase

Question 3

Which of the following is NOT true about hepatitis C virus?

Accepted Answer

Has a live attenuated vaccine

Answer

Most common cause of chronic infection

Answer

Spread by blood transfusion

Answer

Is a flavivirus

Question 4

What is the most common cause of acute aseptic meningitis in children?

Accepted Answer

Enterovirus

Answer

Arbovirus

Answer

Respiratory syncytial virus

Answer

Herpes family

Question 5

Which of the following hepatitis viruses is non-enveloped?

Accepted Answer

Hepatitis A virus (HAV)

Answer

Hepatitis B virus (HBV)

Answer

Hepatitis C virus (HCV)

Answer

Hepatitis D virus (HDV)

Question 6

Human metapneumovirus is structurally similar to which of the following viruses?

Accepted Answer

Respiratory syncytial virus

Answer

Influenza virus

Answer

Measles virus

Answer

Rubella virus

Question 7

What is the most important marker in diagnosing acute Hepatitis B?

Accepted Answer

IgM Anti-HBc

Answer

IgG Anti-HBc

Answer

Anti HBs

Answer

HBsAg

Question 8

Mad Cow disease (Spongiform disease) occurs due to which of the following?

Accepted Answer

Prions (specifically, abnormal prion proteins, not viruses)

Answer

Arena Virus

Answer

Kuru Virus

Answer

Parvo Virus

Question 9

Epstein-Barr virus (EBV) is associated with which of the following conditions, EXCEPT?

Accepted Answer

Verrucous lymphoma

Answer

Nasopharyngeal carcinoma

Answer

Burkitt's lymphoma

Answer

Hodgkin's lymphoma

Question 10

A 3-month-old child was admitted with pneumonia. The microscopy shows the following image. Choose the correct organism.

Accepted Answer

Influenza

Answer

Rotavirus

Answer

Hepatitis virus

Answer

Respiratory syncytial virus

Virology — MCQs

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