Virology Practice Questions

Q: A child presents with fever and redness of a cheek. What is the causative organism for this condition?

Parvovirus B-19. ### Explanation The clinical presentation of fever followed by a characteristic redness of the cheek (often described as a **"slapped-cheek" appearance**) is the hallmark of **Erythema Infectiosum**, also known as **Fifth Disease**. **1. Why Parvovirus B-19 is correct:** Parvovirus B-19 is a DNA virus that infects erythroid progenitor cells. In children, it typically presents with a mild prodromal fever followed by a bright red exanthem on the cheeks (sparing the nasolabial folds). As the facial rash fades, a secondary **"lace-like" or reticular rash** often appears on the trunk and extremities. The rash is immune-mediated and usually appears once the child is no longer contagious. **2. Why the other options are incorrect:** * **Herpes virus:** HSV-1 typically causes gingivostomatitis or herpetic whitlow. While it causes skin lesions, they are vesicular (fluid-filled) rather than a diffuse erythematous "slapped-cheek" rash. * **Adenovirus:** Commonly causes pharyngoconjunctival fever (fever, sore throat, and conjunctivitis). While it can cause a nonspecific rash, it does not present with the classic malar erythema of Fifth disease. * **Rubella:** Also known as German Measles, it presents with a maculopapular rash that starts on the face and spreads downward (cephalocaudal progression) along with characteristic **Forchheimer spots** on the soft palate and retroauricular lymphadenopathy. **Clinical Pearls for NEET-PG:** * **Aplastic Crisis:** Parvovirus B-19 can cause a life-threatening cessation of red blood cell production in patients with high RBC turnover (e.g., **Sickle Cell Anemia**, Hereditary Spherocytosis). * **Pregnancy:** Infection in pregnancy can lead to **Hydrops Fetalis** due to severe fetal anemia. * **Adults:** Often presents with arthralgia or symmetric arthritis rather than a rash. * **Receptor:** The virus enters cells via the **P-antigen** (globoside) on erythrocytes.

Q: A 32-year-old woman seeking to become pregnant visits her physician for a pre-pregnancy examination. Routine prenatal laboratory testing demonstrates the following profile: HBsAg (-), anti-HBsAg (+), anti-HBcAg (-), anti-HBeAg (-), and HBV DNA (-). Which of the following likely represents the status of the patient?

Immunized against hepatitis B. ### Explanation The patient’s serological profile indicates immunity acquired through **vaccination**. **1. Why the Correct Answer is Right:** The presence of **anti-HBsAg (+)** in the absence of other markers is the hallmark of successful immunization. * **HBsAg (-):** Indicates no active infection [1]. * **Anti-HBsAg (+):** Indicates protective immunity. * **Anti-HBcAg (-):** This is the "crucial differentiator." Anti-HBc (Antibody to Core antigen) is only produced in response to an actual viral infection (natural infection). Since vaccines contain only the recombinant surface protein (HBsAg) and no core components, a vaccinated person will be **Anti-HBc negative** [1]. **2. Why the Other Options are Wrong:** * **Option A (Carrier):** A chronic carrier would be **HBsAg (+)** for more than 6 months and **Anti-HBc (+)** (IgG) [1]. * **Option C (Window Period):** During the "window period," HBsAg has disappeared but Anti-HBs has not yet appeared. The only marker typically positive is **Anti-HBc IgM** [1]. * **Option D (Highly Transmissible):** High infectivity is characterized by the presence of **HBsAg (+)** and **HBeAg (+)**, along with high levels of **HBV DNA**. **3. NEET-PG High-Yield Pearls:** * **Natural Infection (Recovered):** HBsAg (-), **Anti-HBc (+)**, Anti-HBs (+) [1]. * **Vaccinated:** HBsAg (-), **Anti-HBc (-)**, Anti-HBs (+). * **HBeAg:** Represents active viral replication and high infectivity. * **Anti-HBs Titer:** A level of **≥10 mIU/mL** after a 3-dose vaccine series is considered protective. * **Isolated Anti-HBc (+):** Can represent a "resolved" infection where Anti-HBs has waned, a "window period," or a false positive.

Q: AIDS was first diagnosed in patients suffering from which of the following conditions?

Pneumocystis carinii pneumonia. **Explanation:** The correct answer is **Pneumocystis carinii pneumonia (PCP)**. The medical recognition of AIDS began in **June 1981**, when the CDC’s *Morbidity and Mortality Weekly Report (MMWR)* described five cases of previously healthy young men in Los Angeles who developed pneumonia caused by *Pneumocystis carinii* (now renamed *Pneumocystis jirovecii*). This was highly unusual as PCP is an opportunistic infection that typically only affects severely immunocompromised individuals. Shortly thereafter, a cluster of **Kaposi Sarcoma** cases was also reported, leading to the identification of the syndrome initially termed "GRID" (Gay-Related Immune Deficiency) before being renamed AIDS in 1982. **Analysis of Options:** * **B (Correct):** PCP was the very first opportunistic infection reported in the 1981 MMWR report that alerted the medical community to the epidemic. * **C (Incorrect):** While Kaposi Sarcoma (caused by HHV-8) was reported very shortly after the initial PCP cases (July 1981), it was the second major condition associated with the outbreak. * **A & D (Incorrect):** While *Cryptococcus neoformans* and *Tuberculosis* are major AIDS-defining illnesses, they were not the index conditions that led to the initial discovery of the disease. **High-Yield Clinical Pearls for NEET-PG:** * **Causative Agent:** HIV is a retrovirus (Lentivirus family) that targets **CD4+ T-cells**. * **Pneumocystis jirovecii:** It is now classified as a **fungus**, not a protozoan. The drug of choice is **Trimethoprim-Sulfamethoxazole (TMP-SMX)**. * **Diagnosis:** The gold standard for HIV screening is **ELISA**, and the confirmatory test (historically) is **Western Blot**, though current protocols favor the **4th Gen p24 antigen/antibody combo assay**. * **CD4 Count:** PCP typically occurs when the CD4 count falls below **200 cells/mm³**.

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.

Question 1

A child presents with fever and redness of a cheek. What is the causative organism for this condition?

Accepted Answer

Parvovirus B-19

Answer

Herpes virus

Answer

Adenovirus

Answer

Rubella

Question 2

A 32-year-old woman seeking to become pregnant visits her physician for a pre-pregnancy examination. Routine prenatal laboratory testing demonstrates the following profile: HBsAg (-), anti-HBsAg (+), anti-HBcAg (-), anti-HBeAg (-), and HBV DNA (-). Which of the following likely represents the status of the patient?

Accepted Answer

Immunized against hepatitis B

Answer

Hepatitis B carrier

Answer

Infected and within the window period

Answer

Infected with hepatitis B and highly transmissible

Question 3

AIDS was first diagnosed in patients suffering from which of the following conditions?

Accepted Answer

Pneumocystis carinii pneumonia

Answer

Cryptococcus neoformans meningitis

Answer

Kaposi sarcoma

Answer

Tuberculosis

Question 4

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 5

What is the primary oncogene expression of HPV?

Accepted Answer

E6E7

Answer

E1E2

Answer

E1E3

Answer

E3E5

Question 6

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 7

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 8

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 9

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 10

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

Virology — MCQs

Virology — MCQs

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