Virology Practice Questions

Q: Epstein-Barr virus (EBV) causes which of the following conditions?

Pancreatic carcinoma. **Explanation:** The question asks to identify which condition is **NOT** typically associated with Epstein-Barr Virus (EBV), as Pancreatic carcinoma is the "odd one out" in this clinical context. **1. Why Pancreatic Carcinoma is the Correct Answer (The Exception):** Epstein-Barr Virus (EBV), a γ-herpesvirus (HHV-4), is known for its strong association with various B-cell and epithelial malignancies. However, **Pancreatic carcinoma** has no established causal link with EBV. Pancreatic cancer is primarily associated with smoking, chronic pancreatitis, and mutations in the KRAS, CDKN2A, TP53, and SMAD4 genes, rather than viral oncogenesis. **2. Analysis of Incorrect Options (Associations with EBV):** * **Glandular Fever (Infectious Mononucleosis):** This is the primary clinical manifestation of EBV infection, characterized by the triad of fever, pharyngitis, and lymphadenopathy. It is diagnosed via the Paul-Bunnell test (heterophile antibodies). * **Burkitt’s Lymphoma:** EBV is strongly linked to the African (endemic) variant of Burkitt’s lymphoma, characterized by the **t(8;14)** translocation involving the c-myc oncogene. * **Nasopharyngeal Carcinoma:** This is an epithelial tumor highly prevalent in Southern China, where EBV DNA is consistently found within the tumor cells. **3. High-Yield Clinical Pearls for NEET-PG:** * **Receptor:** EBV binds to the **CD21** receptor (CR2) on B-cells and the MHC class II molecule. * **Hematology:** Peripheral smear shows **Atypical Lymphocytes (Downey cells)**, which are actually activated T-cells (CD8+) reacting against infected B-cells. * **Other Associations:** Oral Hairy Leukoplakia (in HIV patients), Hodgkin’s Lymphoma (Mixed cellularity subtype), and Gastric Carcinoma (approx. 10% of cases). * **Diagnosis:** Monospot test is the screening test of choice; VCA-IgM (Viral Capsid Antigen) indicates acute infection.

Q: All of the following are caused by RNA viruses, EXCEPT:

Fifth disease. **Explanation:** The core concept tested here is the classification of viruses based on their genetic material. **Correct Answer: D. Fifth Disease** Fifth disease (also known as Erythema Infectiosum) is caused by **Parvovirus B19**. Parvovirus is a **DNA virus**. Specifically, it is unique for being a **non-enveloped, single-stranded DNA (ssDNA)** virus. In the NEET-PG context, remembering that "Parvo" is the only medically significant ssDNA virus is a high-yield fact. **Why the other options are incorrect:** * **A. HIV:** This is a Retrovirus. It contains two copies of single-stranded **RNA** (ssRNA) and uses reverse transcriptase to integrate into the host genome. * **B. Dengue:** Caused by the Dengue virus, which belongs to the *Flaviviridae* family. All Flaviviruses are enveloped, positive-sense **ssRNA** viruses. * **C. Herpangina:** Despite the name sounding like "Herpes" (which is DNA), Herpangina is caused by **Coxsackievirus A**, a member of the *Picornaviridae* family. All Picornaviruses are non-enveloped **ssRNA** viruses. **Clinical Pearls for NEET-PG:** 1. **Fifth Disease Presentation:** Characterized by the "slapped-cheek" rash and can cause aplastic crisis in patients with sickle cell anemia or hereditary spherocytosis. 2. **DNA Virus Mnemonic:** Remember **"HHAPPPPy"** viruses (Herpes, Hepadna, Adeno, Papilloma, Polyoma, Pox, Parvo). All are double-stranded except Parvo (ssDNA). 3. **Herpangina vs. Herpes:** Herpangina (Coxsackie) typically causes vesicles on the **posterior** pharynx/soft palate, whereas Herpetic Gingivostomatitis (HSV-1) involves the **anterior** mouth and gums.

Q: Which one of the following is a double-stranded RNA virus?

Reovirus. **Explanation:** The correct answer is **Reovirus**. In virology, the majority of RNA viruses are single-stranded (ssRNA). **Reoviruses** (which include **Rotavirus**) are the notable exception, characterized by a **segmented, double-stranded RNA (dsRNA)** genome and a double-layered icosahedral capsid. **Why the other options are incorrect:** * **Hepatitis A (Picornavirus):** This is a non-enveloped, **positive-sense single-stranded RNA (+ssRNA)** virus. It is primarily transmitted via the fecal-oral route. * **Hepatitis E (Hepevirus):** Similar to Hepatitis A, it is a non-enveloped **+ssRNA** virus. It is significant in pregnancy due to the high risk of fulminant hepatic failure. * **Coronavirus:** These are enveloped, **+ssRNA** viruses. They possess the largest genomes among RNA viruses and are known for their characteristic "club-shaped" surface projections (peplomers). **High-Yield Clinical Pearls for NEET-PG:** 1. **Mnemonic for dsRNA:** Remember **"REO"** – **R**espiratory **E**nteric **O**rphan. 2. **Rotavirus:** A member of the Reoviridae family, it is the most common cause of severe infantile diarrhea worldwide. It features **11 segments** of dsRNA. 3. **Wheel-like appearance:** Under electron microscopy, Rotavirus exhibits a characteristic "wheel-and-spoke" appearance (Latin *rota* means wheel). 4. **Segmented Genomes:** Other segmented RNA viruses include **B**unyavirus, **O**rthomyxovirus (Influenza), and **A**renavirus (Mnemonic: **BOAR**). Only Reovirus among these is double-stranded.

Q: Which of the following is a marker of acute hepatitis B infection?

DNA polymerase. **Explanation:** The presence of **DNA polymerase** is a direct indicator of active viral replication. In Hepatitis B (HBV), DNA polymerase is found within the core of the virus; its detection in the serum occurs during the early phase of acute infection, coinciding with the peak of viral load and infectivity. While HBsAg is the most common screening marker, DNA polymerase (and HBV DNA) serves as a highly specific marker for the replicative phase of acute hepatitis. **Analysis of Options:** * **Hepatitis core antigen (HBcAg):** This is a "sequestrated" antigen. It is found inside the hepatocyte but **does not circulate freely in the blood**. Therefore, it cannot be used as a serum marker for diagnosis. * **Anti-HBs:** These are protective antibodies that appear after the disappearance of HBsAg. They indicate **recovery and immunity** (either from past infection or vaccination), not an acute infection. * **IgG to core antigen (Anti-HBc IgG):** This marker indicates a **past or chronic infection**. In acute infection, the predominant antibody to the core antigen is of the **IgM** class. **Clinical Pearls for NEET-PG:** * **First marker to appear:** HBsAg. * **Marker of infectivity:** HBeAg and HBV DNA (DNA polymerase). * **Window Period marker:** Anti-HBc IgM (HBsAg and Anti-HBs are both negative). * **Best indicator of vaccination:** Anti-HBs (with all other markers negative). * **Only marker present in all phases of infection (except vaccination):** Anti-HBc (Total).

Q: What is the sequence of genetic material replication followed by a retrovirus upon entering a host cell?

RNA to DNA to RNA. **Explanation:** The hallmark of a **Retrovirus** (e.g., HIV, HTLV) is its ability to reverse the normal flow of genetic information (Central Dogma). 1. **Why Option A is Correct:** Upon entering the host cell, the retrovirus releases its single-stranded positive-sense **RNA** genome. The viral enzyme **Reverse Transcriptase** (RNA-dependent DNA polymerase) converts this RNA into double-stranded **DNA**. This DNA (provirus) integrates into the host genome. Finally, the host’s cellular machinery transcribes this integrated DNA back into new viral **RNA** (genomic RNA and mRNA for protein synthesis). Thus, the sequence is **RNA → DNA → RNA**. 2. **Why Other Options are Incorrect:** * **Option B (RNA to DNA):** This is only the first half of the cycle (Reverse Transcription). Without the final step of transcribing DNA back to RNA, new virions cannot be assembled. * **Option C (DNA to RNA):** This is the standard "Central Dogma" followed by DNA viruses (e.g., Herpesvirus) and host cells, not retroviruses. * **Option D (DNA to RNA to DNA):** This is the replication cycle of **Hepadnaviruses** (e.g., Hepatitis B). They contain a DNA genome, use an RNA intermediate (pre-genome), and use reverse transcriptase to go back to DNA. **High-Yield Clinical Pearls for NEET-PG:** * **Reverse Transcriptase** has three activities: RNA-dependent DNA polymerase, RNase H (degrades the original RNA template), and DNA-dependent DNA polymerase. * **Integrase** is the enzyme responsible for incorporating viral DNA into the host chromosome. * **Hepatitis B** is the only DNA virus that utilizes reverse transcriptase, but its sequence is DNA → RNA → DNA.

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.

Question 1

Epstein-Barr virus (EBV) causes which of the following conditions?

Accepted Answer

Pancreatic carcinoma

Answer

Glandular fever

Answer

Burkitt's lymphoma

Answer

Nasopharyngeal carcinoma

Question 2

All of the following are caused by RNA viruses, EXCEPT:

Accepted Answer

Fifth disease

Answer

HIV

Answer

Dengue

Answer

Herpangina

Question 3

An elderly male presents with fever, cough, and shortness of breath for 2 weeks. He has a history of chronic bronchitis and diabetes, and recent travel to Wuhan City, China. What is the symmetry of the causative virus?

Accepted Answer

Enveloped helical symmetry

Answer

Naked helical symmetry

Answer

Complex symmetry

Answer

Icosahedral symmetry

Question 4

Which one of the following is a double-stranded RNA virus?

Accepted Answer

Reovirus

Answer

Hepatitis A

Answer

Hepatitis E

Answer

Coronavirus

Question 5

Which of the following is a marker of acute hepatitis B infection?

Accepted Answer

DNA polymerase

Answer

Hepatitis core antigen

Answer

Anti HBs

Answer

IgG to core antigen

Question 6

What is the sequence of genetic material replication followed by a retrovirus upon entering a host cell?

Accepted Answer

RNA to DNA to RNA

Answer

RNA to DNA

Answer

DNA to RNA

Answer

DNA to RNA to DNA

Question 7

All the following statements are true for the viral genome in HIV, except?

Accepted Answer

They consist of DNA dependent DNA polymerase activity

Answer

They are diploid

Answer

They consist of three major genes-gag, pol and env characteristic of all retroviruses

Answer

They are the most complex of human retroviruses

Question 8

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 9

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 10

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

Virology — MCQs

Virology — MCQs

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