Virology Practice Questions

Q: What is the primary oncogene expression of HPV?

E6E7. **Explanation:** Human Papillomavirus (HPV), particularly high-risk types 16 and 18, causes malignant transformation primarily through the expression of two early genes: **E6 and E7**. These are considered the primary oncogenes because they neutralize host tumor suppressor proteins. * **E6 Protein:** Binds to the **p53** tumor suppressor protein, leading to its ubiquitination and subsequent degradation via the proteasome. This prevents p53-mediated apoptosis and cell cycle arrest. * **E7 Protein:** Binds to the hypophosphorylated (active) form of the **Retinoblastoma (Rb)** protein. This releases the **E2F transcription factor**, which promotes the transition of the cell from the G1 to the S phase, leading to uncontrolled proliferation. **Analysis of Incorrect Options:** * **E1 & E2:** These are involved in viral DNA replication and transcriptional regulation. Loss of E2 (due to viral integration into the host genome) actually leads to the *overexpression* of E6 and E7. * **E3 & E5:** E3 is not a major functional gene in HPV. E5 has some oncogenic potential (interacting with growth factor receptors), but it is not the "primary" driver compared to E6/E7. **High-Yield Clinical Pearls for NEET-PG:** * **HPV 16 & 18:** Responsible for ~70% of Cervical Cancer cases. * **HPV 6 & 11:** Low-risk types causing Genital Warts (Condyloma acuminatum). * **Integration:** Malignancy occurs when the circular HPV genome breaks at the **E2 ORF** and integrates into the host DNA, removing the "brake" on E6/E7 expression. * **Screening:** Koilocytes (cells with perinuclear halo and wrinkled nuclei) on a Pap smear are pathognomonic for HPV infection.

Q: Which of the following Ebola virus strains is considered non-pathogenic to humans?

Reston. **Explanation:** The **Ebola virus** belongs to the family *Filoviridae*. There are six identified species within the genus *Ebolavirus*, but their pathogenicity in humans varies significantly. **Why Reston is the correct answer:** The **Reston virus (RESTV)** is unique because, while it can cause severe and fatal Hemorrhagic Fever in non-human primates (monkeys) and can infect pigs, it is **non-pathogenic to humans**. Although humans can seroconvert (develop antibodies) after exposure, there have been no documented cases of clinical illness or death in humans to date. It was first discovered in 1989 in laboratory monkeys imported from the Philippines to Reston, Virginia. **Analysis of incorrect options:** * **A. Zaire ebolavirus:** The most virulent and well-known strain. It is responsible for the largest outbreaks, including the 2014–2016 West Africa epidemic, with mortality rates as high as 90%. * **C. Cote d'Ivoire (Taï Forest virus):** Known to cause human disease. The first case was a scientist who performed an autopsy on a wild chimpanzee; it causes severe respiratory and hemorrhagic symptoms. * **D. Bundibugyo ebolavirus:** Identified in 2007 in Uganda. It is pathogenic to humans, though it typically has a lower case-fatality rate (approx. 25-40%) compared to the Zaire strain. **High-Yield NEET-PG Pearls:** * **Transmission:** Primarily through direct contact with infected blood, secretions, or organs (zoonotic source: Fruit bats are the natural reservoir). * **Structure:** Negative-sense, single-stranded, enveloped RNA virus with a characteristic **filamentous/shepherd’s crook** appearance. * **Diagnosis:** Gold standard is **RT-PCR**; ELISA for antigen detection is also used. * **Vaccine:** The **rVSV-ZEBOV** vaccine is highly effective against the Zaire strain.

Q: Coxsackie A virus does not cause which of the following conditions?

Laryngotracheobronchitis. **Explanation:** The correct answer is **Laryngotracheobronchitis (C)**. Laryngotracheobronchitis, commonly known as **Croup**, is most frequently caused by the **Parainfluenza virus (Type 1 and 2)**. It is characterized by subglottic edema leading to a "barking" cough and inspiratory stridor. Coxsackie viruses are not typical causative agents for this respiratory syndrome. **Analysis of other options:** * **Herpangina (A):** This is a classic manifestation of **Coxsackie A** (specifically types 1–10, 16, and 22). It presents with high fever, sore throat, and vesiculopapular lesions on the posterior pharynx (soft palate and tonsillar pillars). * **Hand, Foot, and Mouth Disease (B):** Primarily caused by **Coxsackie A16** (and Enterovirus 71). It presents with vesicular eruptions on the palms, soles, and oral mucosa. * **Aseptic Meningitis (D):** Both Coxsackie A and B are leading causes of viral (aseptic) meningitis. While Coxsackie B is more common, several serotypes of Coxsackie A are frequently implicated. **High-Yield Clinical Pearls for NEET-PG:** * **Coxsackie A vs. B:** Remember the mnemonic **"A for Appendages/Apertures"** (Skin/HFM, Mouth/Herpangina) and **"B for Body"** (Heart/Myocarditis, Pleura/Bornholm disease, Pancreas/Diabetes). * **Bornholm Disease:** Also known as "Devil’s Grip" (Pleurodynia), it is caused by **Coxsackie B**. * **Myocarditis/Pericarditis:** Coxsackie B is the most common viral cause of acute myocarditis. * **Seasonality:** Enteroviruses (including Coxsackie) typically peak during the **summer and fall** months.

Q: Epstein-Barr virus is associated with all the following conditions EXCEPT:

Laennec's cirrhosis. **Explanation:** **Epstein-Barr Virus (EBV)**, a member of the *Herpesviridae* family (HHV-4), is a ubiquitous virus primarily known for causing Infectious Mononucleosis. It is associated with a wide spectrum of clinical conditions, ranging from benign lymphoproliferative disorders to malignancies and neurological complications. **Why Laennec’s Cirrhosis is the correct answer:** Laennec’s cirrhosis is a historical term for **Alcoholic Cirrhosis**, characterized by micronodular scarring of the liver due to chronic alcohol abuse. It is a metabolic and toxic consequence of ethanol consumption, not an infectious process. EBV does not cause chronic cirrhosis or permanent fibrotic liver remodeling. **Analysis of Incorrect Options:** * **Hepatitis:** EBV is a "non-hepatotropic" virus that frequently causes mild, self-limiting hepatitis as part of the Infectious Mononucleosis syndrome. It typically presents with transiently elevated transaminases and hepatomegaly. * **Bell’s Palsy:** EBV is a recognized viral trigger for facial nerve (CN VII) paralysis. It is often cited alongside HSV-1 and VZV as a cause of lower motor neuron facial palsy. * **Guillain-Barré Syndrome (GBS):** EBV is one of the classic viral triggers for GBS (an acute inflammatory demyelinating polyneuropathy), following the molecular mimicry mechanism. **High-Yield Clinical Pearls for NEET-PG:** * **Malignancies:** EBV is strongly linked to Burkitt’s Lymphoma (t 8;14), Nasopharyngeal Carcinoma, Hodgkin’s Lymphoma (Mixed cellularity), and Oral Hairy Leukoplakia (in HIV). * **Diagnosis:** Look for **Atypical Lymphocytes (Downey cells)** on peripheral smear and a positive **Paul-Bunnell Test** (Heterophile antibodies). * **Receptor:** EBV binds to the **CD21** receptor (CR2) on B-cells.

Q: Herpes viruses acquire their envelope from which cellular membrane?

Nuclear membrane. **Explanation:** The **Herpesviridae** family is unique among DNA viruses because of its specific replication and assembly process. Unlike most enveloped viruses that acquire their lipid bilayer from the plasma membrane, Herpes viruses undergo **primary budding through the inner nuclear membrane.** 1. **Why Option A is Correct:** After the viral DNA replicates and nucleocapsids are assembled inside the host cell nucleus, they must exit to the cytoplasm. The nucleocapsid buds through the inner nuclear membrane into the perinuclear space, acquiring its initial envelope. While this envelope undergoes a complex "de-envelopment and re-envelopment" process at the Golgi apparatus for final maturation, the **primary source** of the herpesvirus envelope is the **nuclear membrane**. 2. **Why Other Options are Incorrect:** * **Option B (Nucleolar membrane):** The nucleolus is a non-membrane-bound structure within the nucleus responsible for ribosome synthesis; it does not provide envelopes for viruses. * **Option C (Cytoplasmic/Plasma membrane):** Most other enveloped viruses (like Orthomyxoviruses or Retroviruses) acquire their envelope from the plasma membrane as they exit the cell. Herpes viruses are the classic exception to this rule. **NEET-PG High-Yield Pearls:** * **Tzanck Smear:** Look for multinucleated giant cells and **Cowdry Type A** intranuclear inclusion bodies (Lipschütz bodies) in HSV and VZV infections. * **Site of Latency:** HSV-1 (Trigeminal ganglion), HSV-2 (Sacral ganglion), VZV (Dorsal root ganglion), EBV (B-cells). * **Rule of Thumb:** All DNA viruses replicate in the nucleus **except Poxvirus** (replicates in the cytoplasm). All RNA viruses replicate in the cytoplasm **except Influenza and HIV/Retrovirus** (replicate in the nucleus).

Q: What is the primary receptor for Epstein-Barr virus (EBV)?

Complement receptor 2 (CR2). **Explanation:** The **Epstein-Barr Virus (EBV)**, a member of the *Herpesviridae* family (HHV-4), specifically targets B lymphocytes. The primary mechanism of entry involves the viral envelope glycoprotein **gp350/220** binding to the **Complement Receptor 2 (CR2)**, also known as **CD21**, located on the surface of B cells. This interaction is the classic example of viral tropism in medical microbiology. **Analysis of Options:** * **Option B (Correct):** CR2 (CD21) is the definitive receptor for EBV. It is normally involved in B-cell activation by binding to the C3d component of the complement system. EBV "mimics" this ligand to gain entry. * **Option A:** **CR1 (CD35)** is a receptor for C3b/C4b found on erythrocytes and leukocytes; it does not facilitate EBV entry. * **Option C & D:** **CD19 and CD20** are definitive B-cell markers used in clinical practice (e.g., Rituximab targets CD20), but they do not serve as the primary attachment point for EBV. **High-Yield Clinical Pearls for NEET-PG:** * **Receptor Synonym:** Always remember **CR2 = CD21**. A common mnemonic is *"EBV drinks at the Bar (B-cell) at age 21 (CD21)."* * **Secondary Receptor:** While CD21 is for attachment, EBV uses **MHC Class II** molecules as a co-receptor for membrane fusion. * **Atypical Lymphocytes:** In Infectious Mononucleosis, the "atypical cells" seen on a peripheral smear are **activated CD8+ T-cells** (Downey cells) reacting against the infected B-cells, not the infected B-cells themselves. * **Associated Malignancies:** EBV is strongly linked to Burkitt Lymphoma (t8;14), Nasopharyngeal Carcinoma, and Hodgkin Lymphoma.

Q: What is the serological pattern observed for acute Hepatitis B with active viral replication?

HBsAg, HBeAg, IgM Anti-HBc. **Explanation:** The serological diagnosis of Hepatitis B (HBV) depends on identifying specific antigens and antibodies that appear at different stages of the infection. **Why Option A is Correct:** In **Acute Hepatitis B**, the first marker to appear is **HBsAg** (Hepatitis B Surface Antigen), indicating active infection. The presence of **HBeAg** (Hepatitis B e-Antigen) is a hallmark of **active viral replication** and high infectivity. Crucially, the differentiation between acute and chronic infection relies on the core antibody: **IgM anti-HBc** is the definitive marker for acute infection (it is the only marker present during the "window period" when HBsAg and Anti-HBs are both negative). **Analysis of Incorrect Options:** * **Option B:** HBsAg with **IgG anti-HBc** indicates **Chronic Hepatitis B**. IgG replaces IgM after approximately 6 months. * **Option C:** HBeAg alone is never used for diagnosis; it is a supplemental marker for replication and must be interpreted alongside HBsAg. * **Option D:** HBsAg alone indicates infection but does not specify the stage (acute vs. chronic) or the status of viral replication. **High-Yield NEET-PG Pearls:** 1. **Window Period:** The interval between the disappearance of HBsAg and the appearance of Anti-HBs. The diagnostic marker here is **IgM anti-HBc**. 2. **Best marker for infectivity:** HBeAg (or HBV-DNA levels). 3. **Marker of Immunity:** **Anti-HBs** (following vaccination or recovery). 4. **Chronic Carrier:** Defined by the persistence of HBsAg for >6 months. 5. **First marker to appear:** HBsAg.

Question 1

A 29-year-old male is found to be HBsAg positive with highly increased SCOT levels but HBeAg negative. Which of the following is true about the status of the patient?

Accepted Answer

Precore mutant

Answer

Core-promoter mutant

Answer

Wild type mutant

Answer

Surface mutant

Question 2

What is the primary oncogene expression of HPV?

Accepted Answer

E6E7

Answer

E1E2

Answer

E1E3

Answer

E3E5

Question 3

A person had an episode of dengue serotype 1, followed by an infection with serotype 2 two years later. What is the likely effect of the second episode?

Accepted Answer

Increased chances of developing Dengue Hemorrhagic Fever (DHF).

Answer

Mild dengue fever due to the presence of neutralizing antibodies.

Answer

No chances of developing DHF.

Answer

No effect on the present illness.

Question 4

A 34-year-old male patient visits a physician with complaints of fatigue, weight loss, night sweats, and "swollen glands." The physician also observes that he has an oral yeast infection. Which of the following tests would most likely reveal the cause of his problems?

Accepted Answer

An HIV ELISA test

Answer

A test for CD8 lymphocytes

Answer

A human T-lymphotropic virus type I (HTLV-I) test

Answer

A test for infectious mononucleosis

Question 5

Which of the following Ebola virus strains is considered non-pathogenic to humans?

Accepted Answer

Reston

Answer

Zaire

Answer

Cote d'Ivoire

Answer

Bundibugyo

Question 6

Coxsackie A virus does not cause which of the following conditions?

Accepted Answer

Laryngotracheobronchitis

Answer

Herpangina

Answer

Hand, foot and mouth disease (HFM)

Answer

Aseptic meningitis

Question 7

Epstein-Barr virus is associated with all the following conditions EXCEPT:

Accepted Answer

Laennec's cirrhosis

Answer

Bell's palsy

Answer

Hepatitis

Answer

Guillain-Barré syndrome

Question 8

Herpes viruses acquire their envelope from which cellular membrane?

Accepted Answer

Nuclear membrane

Answer

Nucleolar membrane

Answer

Cytoplasmic membrane

Answer

None of the above

Question 9

What is the primary receptor for Epstein-Barr virus (EBV)?

Accepted Answer

Complement receptor 2 (CR2)

Answer

Complement receptor 1 (CR1)

Answer

CD20

Answer

CD19

Question 10

What is the serological pattern observed for acute Hepatitis B with active viral replication?

Accepted Answer

HBsAg, HBeAg, IgM Anti-HBc

Answer

HBsAg, IgG Anti-HBc

Answer

HBeAg

Answer

HBsAg

Virology — MCQs

Virology — MCQs

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