Virology Practice Questions

Q: Which of the Hepatitis B Virus serological markers indicates the earliest evidence of Hepatitis B infection?

HBsAg. ### Explanation **Correct Option: D. HBsAg** Hepatitis B Surface Antigen (HBsAg) is the **first serological marker** to appear in the blood after infection. It typically becomes detectable 2 to 8 weeks before the onset of clinical symptoms and biochemical evidence (elevated ALT/AST). Its presence indicates that the individual is currently infected (either acute or chronic) and is potentially infectious. **Analysis of Incorrect Options:** * **A. Anti-HBs:** This antibody appears only after the disappearance of HBsAg or following successful vaccination. It signifies **immunity** and recovery, appearing much later in the disease course. * **B. Anti-HBc:** This is the first **antibody** to appear (specifically the IgM isotype). While it is an early marker of the host's immune response, it appears after HBsAg has already been circulating. * **C. HBeAg:** This marker indicates active viral replication and high infectivity. While it appears early, it usually surfaces shortly **after** HBsAg. **NEET-PG High-Yield Pearls:** * **Window Period:** The interval during which HBsAg has disappeared but Anti-HBs has not yet appeared. During this phase, **IgM Anti-HBc** is the only diagnostic marker of acute infection. * **Chronic Infection:** Defined by the persistence of HBsAg in the serum for **more than 6 months**. * **Infectivity Marker:** HBeAg and HBV-DNA levels are the best indicators of high viral load and transmissibility. * **Vaccination:** A person vaccinated against HBV will be positive for **Anti-HBs only** (negative for Anti-HBc).

Q: Which virus can cause hemorrhage?

Adenovirus. **Explanation:** The correct answer is **Adenovirus**. Adenovirus is a double-stranded DNA virus known for its diverse tissue tropism. Specifically, **Adenovirus serotypes 11 and 21** are the most common causes of **Acute Hemorrhagic Cystitis**, a condition characterized by sudden onset hematuria (blood in urine), dysuria, and frequency, primarily seen in children (more common in boys) and immunocompromised patients. **Analysis of Options:** * **Adenovirus (Correct):** Beyond respiratory infections and conjunctivitis (Pink eye), it is a classic cause of viral-induced hemorrhage in the urinary bladder mucosa. * **Parvovirus (Incorrect):** Parvovirus B19 primarily targets erythrocyte precursors in the bone marrow. It causes Erythema Infectiosum (Fifth disease), aplastic crisis in sickle cell patients, and hydrops fetalis, but is not typically associated with hemorrhage. * **HPV (Incorrect):** Human Papillomavirus is associated with benign warts and mucosal malignancies (Cervical/Anal cancer) via epithelial proliferation, not acute hemorrhagic manifestations. * **Coronavirus (Incorrect):** While severe COVID-19 can lead to coagulopathies and microvascular thrombosis, the virus itself is not a primary cause of direct tissue hemorrhage in the same clinical context as Adenovirus. **High-Yield Clinical Pearls for NEET-PG:** * **Hemorrhagic Cystitis:** If the question specifies a post-transplant patient, consider **BK Virus** (Polyomavirus) or Adenovirus. * **Pharyngoconjunctival Fever:** Caused by Adenovirus serotypes 3 and 7 (Triad: Fever, Pharyngitis, Conjunctivitis). * **Epidemic Keratoconjunctivitis (Shipyard eye):** Caused by Adenovirus serotypes 8, 19, and 37. * **Intussusception:** Adenovirus is a known trigger for lymphoid hyperplasia (Peyer's patches), leading to intussusception in children.

Q: Ribavirin, a synthetic nucleoside structurally related to guanosine, has been successfully used in therapy against which of the following viruses?

Respiratory syncytial virus. **Explanation:** **Ribavirin** is a synthetic guanosine analogue that exerts its antiviral effect by interfering with the replication of viral RNA. It inhibits the enzyme **IMP dehydrogenase**, leading to the depletion of intracellular GTP pools, and interferes with the capping of viral mRNA. 1. **Why Option A is Correct:** Ribavirin is primarily indicated for the treatment of **Respiratory Syncytial Virus (RSV)** infections, particularly in severe cases involving hospitalized infants and children. It is administered via a small-particle aerosol (nebulized form). It is also used orally in combination with Interferon-alpha for **Hepatitis C** (Genotype 1 and 4) and is the drug of choice for **Lassa fever**. 2. **Why Other Options are Incorrect:** * **B. Herpes simplex virus:** Treated with **Acyclovir**, Valacyclovir, or Famciclovir, which are deoxyguanosine analogues that specifically inhibit viral DNA polymerase. * **C. Hepatitis B virus:** Managed with reverse transcriptase inhibitors like **Entecavir** or **Tenofovir**, or Interferon-alpha. Ribavirin has no significant activity against HBV. * **D. Group A coxsackievirus:** There is currently no specific FDA-approved antiviral therapy for Coxsackievirus; management is primarily supportive. **High-Yield Clinical Pearls for NEET-PG:** * **Teratogenicity:** Ribavirin is strictly contraindicated in pregnancy (Category X). Both male and female patients must use contraception for 6 months after treatment. * **Dose-dependent Hemolytic Anemia:** This is the most common and characteristic systemic side effect of oral Ribavirin. * **Spectrum:** It is a broad-spectrum antiviral effective against both DNA and RNA viruses, but its clinical utility is limited by toxicity.

Q: Colorado tick fever is the only known human infection caused by which of the following?

Coltivirus. **Explanation:** **Colorado Tick Fever (CTF)** is a viral zoonotic disease transmitted by the bite of the Rocky Mountain wood tick (*Dermacentor andersoni*). It is caused by the **Coltivirus**, which belongs to the family **Reoviridae**. 1. **Why Coltivirus is correct:** Coltiviruses are characterized by a genome consisting of 12 segments of double-stranded RNA (dsRNA). In humans, Colorado Tick Fever is the only significant clinical infection caused by this genus [1]. The virus infects erythrocyte precursor cells, allowing it to persist in the bloodstream for several weeks, protected from the immune system. 2. **Why other options are incorrect:** * **Reovirus:** While Coltivirus is in the Reoviridae family, the genus *Orthoreovirus* (often just called Reovirus) typically causes mild, often asymptomatic respiratory or gastrointestinal illnesses in humans, not CTF. * **Rotavirus:** Also a member of Reoviridae, it is the leading cause of severe dehydrating diarrhea in infants and young children worldwide, transmitted via the fecal-oral route [1]. * **Coronavirus:** These are enveloped, positive-sense single-stranded RNA viruses (family Coronaviridae) responsible for respiratory infections ranging from the common cold to SARS and COVID-19 [1]. **High-Yield Clinical Pearls for NEET-PG:** * **Vector:** *Dermacentor andersoni* (Rocky Mountain wood tick). * **Clinical Presentation:** Characterized by a **"saddleback" fever** (biphasic fever pattern), chills, headache, and myalgia. * **Diagnosis:** Suggested by leukopenia (low WBC) and confirmed by PCR or virus isolation. * **Key Distinction:** Unlike Rocky Mountain Spotted Fever (caused by *Rickettsia rickettsii*), CTF is viral and does not respond to antibiotics.

Q: Miyagawa body is characteristically seen in which of the following conditions?

Lymphogranuloma venereum (LGV). **Explanation:** **Miyagawa bodies** (also known as elementary bodies) are the characteristic intracellular inclusion bodies seen in **Lymphogranuloma venereum (LGV)**, which is caused by *Chlamydia trachomatis* serotypes L1, L2, and L3. 1. **Why LGV is correct:** *Chlamydia* are obligate intracellular bacteria with a unique life cycle involving two forms: the **Elementary Body (EB)** and the **Reticulate Body (RB)**. In LGV, these EBs aggregate within the cytoplasm of infected host cells (macrophages and epithelial cells) to form large, basophilic inclusion bodies known as Miyagawa bodies. These are diagnostic when visualized under Giemsa or iodine stains. 2. **Why other options are incorrect:** * **Kala-azar (Visceral Leishmaniasis):** Characterized by **LD bodies** (Leishman-Donovan bodies), which are the amastigote stage of *Leishmania donovani* found within macrophages. * **Syphilis:** Caused by *Treponema pallidum*. It does not form inclusion bodies; diagnosis relies on dark-ground microscopy or serology (VDRL/TPHA). * **Granuloma inguinale (Donovanosis):** Caused by *Klebsiella granulomatis*. It is characterized by **Donovan bodies**, which are safety-pin shaped organisms seen within large mononuclear cells. **High-Yield Clinical Pearls for NEET-PG:** * **LGV Clinical Triad:** Primary painless vesicle, painful inguinal lymphadenopathy (**Groove sign**), and proctocolitis. * **Frei’s Test:** A delayed hypersensitivity skin test previously used for LGV (now largely replaced by NAAT). * **Halberstaedter-Prowazek bodies:** Inclusion bodies seen in *Chlamydia trachomatis* serotypes A, B, and C (Trachoma). * **Levinthal-Cole-Lillie (LCL) bodies:** Inclusion bodies seen in *Psittacosis*.

Q: A 32-year-old man presents to the emergency room with a severe headache. Nuchal rigidity is found on physical examination. Lumbar puncture demonstrates cerebrospinal fluid with markedly increased lymphocytes and no other increased cell populations. Which of the following agents is the most likely cause of his symptoms?

Herpes virus. ### Explanation The clinical presentation of headache and nuchal rigidity indicates **meningitis**. The key to solving this case lies in the CSF analysis: **markedly increased lymphocytes** with no other cell types (like neutrophils) suggests **Aseptic (Viral) Meningitis**. **1. Why Herpes Virus is Correct:** Viral infections are the most common cause of lymphocytic pleocytosis in the CSF. While Enteroviruses are the most frequent cause of viral meningitis overall, **Herpes Simplex Virus (HSV)**—specifically HSV-2—is a significant cause of aseptic meningitis in adults. In viral meningitis, CSF typically shows normal glucose, normal to slightly elevated protein, and a predominance of lymphocytes. **2. Why the Other Options are Incorrect:** * **A. Escherichia coli & B. Haemophilus influenzae:** These are causes of **Acute Pyogenic (Bacterial) Meningitis**. The CSF profile would show a predominance of **neutrophils** (polymorphonuclear leukocytes), significantly decreased glucose, and markedly elevated protein. * **D. Mycobacterium tuberculosis:** While TB meningitis causes lymphocytic pleocytosis, it is typically associated with a **"cobweb" appearance** of CSF, very high protein levels, and **significantly decreased glucose**. The clinical course is also usually more subacute/chronic rather than an emergency presentation. **3. NEET-PG High-Yield Pearls:** * **HSV-1** is the most common cause of sporadic **Viral Encephalitis** (targeting the temporal lobes). * **HSV-2** is more commonly associated with **Viral Meningitis** (Mollaret’s meningitis). * **CSF Findings Summary:** * *Bacterial:* ↑ Neutrophils, ↓ Glucose, ↑↑ Protein. * *Viral:* ↑ Lymphocytes, Normal Glucose, Normal/↑ Protein. * *Tubercular:* ↑ Lymphocytes, ↓ Glucose, ↑ Protein (Fibrin web).

Q: Which virus is a common cause of diarrheal diseases in infants?

Rotavirus. **Explanation:** **1. Why Rotavirus is Correct:** Rotavirus (a Reovirus) is the **most common cause of severe, dehydrating diarrhea in infants and young children (6–24 months)** worldwide. It primarily infects the mature enterocytes of the small intestine. The pathophysiology involves the **NSP4 enterotoxin**, which induces a secretory diarrhea by increasing intracellular calcium and disrupting SGLT-1 mediated glucose absorption. In the NEET-PG context, remember it follows a "winter seasonality" in temperate climates and is characterized by a "wheel-like" appearance on electron microscopy. **2. Analysis of Incorrect Options:** * **B. Norwalk virus (Norovirus):** While it is the leading cause of viral gastroenteritis outbreaks across all age groups, it is classically associated with **adults**, cruise ships, schools, and shellfish consumption. * **C. Adenovirus:** Specifically Serotypes **40 and 41** (Subgroup F) cause diarrhea in children. While significant, they are less common than Rotavirus and typically cause a more prolonged, less severe illness. * **D. Hepatadenovirus:** This is a misnomer or refers to *Hepadnaviridae* (like Hepatitis B), which affects the liver, not the gastrointestinal tract to cause diarrhea. **3. High-Yield Clinical Pearls for NEET-PG:** * **Morphology:** Double-stranded RNA (dsRNA), segmented (11 segments), non-enveloped, icosahedral. * **Diagnosis:** Latex agglutination or ELISA for VP6 antigen in stool. * **Vaccines:** Live attenuated oral vaccines (**Rotarix** - monovalent; **RotaTeq** - pentavalent) are part of the Universal Immunization Programme (UIP) in India. * **Complication:** A rare but classic association with Rotavirus vaccines is **intussusception**.

Question 1

Which of the following statements is FALSE regarding Negri bodies?

Accepted Answer

They contain rabies virus antigen.

Answer

They are pathognomonic of rabies.

Answer

They are found in the brain.

Answer

They are cytoplasmic inclusion bodies.

Question 2

Which of the Hepatitis B Virus serological markers indicates the earliest evidence of Hepatitis B infection?

Accepted Answer

HBsAg

Answer

Anti-HBs

Answer

Anti-HBc

Answer

HBeAg

Question 3

Which virus can cause hemorrhage?

Accepted Answer

Adenovirus

Answer

Parvovirus

Answer

HPV

Answer

Coronavirus

Question 4

A 35-year-old man developed headache, nausea, vomiting, and sore throat 8 weeks after returning from a trip abroad. He eventually refused to drink water and had episodes of profuse salivation, difficulty in breathing, and hallucinations. Two days after the patient died of cardiac arrest, it was learned that he had been bitten by a dog while on his trip. Which of the following treatments, if given immediately after the dog bite, could have helped prevent this disease?

Accepted Answer

Rabies immune globulin plus rabies vaccine

Answer

Broad-spectrum antibiotics

Answer

High-dose acyclovir

Answer

IV ribavirin

Question 5

Ribavirin, a synthetic nucleoside structurally related to guanosine, has been successfully used in therapy against which of the following viruses?

Accepted Answer

Respiratory syncytial virus

Answer

Herpes simplex virus

Answer

Hepatitis B virus

Answer

Group A coxsackievirus

Question 6

Colorado tick fever is the only known human infection caused by which of the following?

Accepted Answer

Coltivirus

Answer

Reovirus

Answer

Rotavirus

Answer

Coronavirus

Question 7

Miyagawa body is characteristically seen in which of the following conditions?

Accepted Answer

Lymphogranuloma venereum (LGV)

Answer

Kala azar

Answer

Syphilis

Answer

Granuloma inguinale

Question 8

A 32-year-old man presents to the emergency room with a severe headache. Nuchal rigidity is found on physical examination. Lumbar puncture demonstrates cerebrospinal fluid with markedly increased lymphocytes and no other increased cell populations. Which of the following agents is the most likely cause of his symptoms?

Accepted Answer

Herpes virus

Answer

Escherichia coli

Answer

Haemophilus influenzae

Answer

Mycobacterium tuberculosis

Question 9

Which virus spreads by both hematogenous and neural routes?

Accepted Answer

Poliovirus

Answer

Rabies virus

Answer

Varicella zoster virus

Answer

Epstein-Barr virus

Question 10

Which virus is a common cause of diarrheal diseases in infants?

Accepted Answer

Rotavirus

Answer

Norwalk virus

Answer

Adenovirus

Answer

Hepatadenovirus

Virology — MCQs

Virology — MCQs

On this page

Practice by Chapter

Want unlimited practice?