Virology Practice Questions

Q: Infection with which of the following agents is particularly dangerous for anemic patients?

Parvovirus. **Explanation:** **1. Why Parvovirus B19 is the Correct Answer:** Parvovirus B19 is uniquely dangerous for anemic patients because it has a specific tropism for **erythroid progenitor cells**. The virus enters these cells via the **P-antigen** (globoside) receptor and replicates within them, leading to direct cytotoxicity and the temporary cessation of erythropoiesis. In healthy individuals, this brief pause in red blood cell (RBC) production is clinically silent. However, in patients with high RBC turnover (e.g., **Sickle Cell Anemia, Hereditary Spherocytosis, Thalassemia**), the bone marrow cannot compensate for the loss. This results in a life-threatening **Aplastic Crisis**, characterized by a sudden drop in hemoglobin and a dangerously low reticulocyte count. **2. Why Other Options are Incorrect:** * **Adenovirus:** Primarily causes respiratory infections, conjunctivitis (pink eye), and hemorrhagic cystitis. It does not target erythroid precursors. * **Cytomegalovirus (CMV):** A member of the Herpesviridae family, it typically causes infectious mononucleosis-like symptoms or severe systemic disease in immunocompromised hosts (retinitis, colitis), but not selective bone marrow suppression of RBCs. * **Herpes Simplex Virus (HSV):** Primarily associated with mucocutaneous lesions (cold sores, genital herpes) and encephalitis; it does not impact erythropoiesis. **3. NEET-PG High-Yield Clinical Pearls:** * **Erythema Infectiosum (Fifth Disease):** Classic presentation in children featuring a "slapped-cheek" rash. * **Hydrops Fetalis:** If a pregnant woman is infected, the virus can cross the placenta, causing severe fetal anemia, high-output cardiac failure, and fetal death. * **Diagnosis:** Look for **"Giant Pronormoblasts"** in the bone marrow and a **low reticulocyte count** (distinguishes aplastic crisis from hemolytic crisis). * **Receptor:** P-antigen (individuals lacking P-antigen are resistant to Parvovirus B19).

Q: A nurse has been found to be seropositive for both HbsAg and HBeAg. She is suffering from which of the following conditions?

Acute Hepatitis B infection. ### Explanation The presence of **HBsAg** (Hepatitis B surface Antigen) indicates that the patient is currently infected with the Hepatitis B virus [1]. The presence of **HBeAg** (Hepatitis B envelope Antigen) is a marker of active viral replication and high infectivity. **Why Acute Hepatitis B is the correct answer:** In the clinical context of a healthcare worker (like a nurse) presenting with these markers, it typically represents an **Acute Hepatitis B infection**. During the early phase of acute infection, HBsAg appears first, followed closely by HBeAg [1]. While HBeAg can also be present in the "Immune Tolerant" or "Reactive" phases of chronic infection, in standard NEET-PG questions, the combination of HBsAg and HBeAg without further qualifiers (like duration >6 months) is the classic laboratory profile for a highly infectious acute case. **Analysis of Incorrect Options:** * **Option A:** HBeAg stands for "envelope" antigen of HBV, not Hepatitis E. Hepatitis E is a separate RNA virus diagnosed via Anti-HEV IgM. * **Option C:** Chronic infection is defined by the persistence of HBsAg for **more than 6 months** [1]. Without a longitudinal history, acute infection is the primary clinical assumption. * **Option D:** In a past/resolved infection, HBsAg is cleared and **Anti-HBs antibodies** are present [1]. HBeAg would also be absent. --- ### High-Yield Clinical Pearls for NEET-PG * **HBsAg:** First marker to appear; indicates current infection (acute or chronic) [1]. * **HBeAg:** Indicates **high viral load**, active replication, and maximum infectivity. * **Anti-HBc IgM:** The **best marker for Acute HBV** (especially during the "Window Period" when HBsAg and Anti-HBs are both negative) [1]. * **Anti-HBc IgG:** Indicates "Remote" infection; it persists for life. * **Anti-HBs:** Indicates **immunity** (either from recovery or vaccination) [1]. If it is the *only* positive marker, it indicates vaccination.

Q: Which of the following is the characteristic site for the detection of Varicella-zoster virus (VZV) in active infection?

Skin. Explanation: **Varicella-zoster virus (VZV)**, a member of the *Alphaherpesvirinae* subfamily, is the causative agent of chickenpox (primary infection) and herpes zoster (reactivation) [1], [3]. The virus is highly **epitheliotropic**, meaning it has a specific predilection for infecting and replicating within skin cells [1]. 1. **Why Skin is Correct:** During active infection, VZV travels from the dorsal root ganglia to the skin via sensory nerves. It replicates in the epidermis, leading to the characteristic "dewdrop on a rose petal" vesicular rash [1], [4]. The fluid within these vesicles contains a high viral load, making the **skin (vesicle fluid or scrapings)** the primary and most reliable site for detection via PCR, Tzanck smear, or viral culture [2]. 2. **Why Other Options are Incorrect:** * **Cervical tissue:** This is the characteristic site for Human Papillomavirus (HPV) or Herpes Simplex Virus-2 (HSV-2), not VZV. * **Synovial fluid:** While some viruses like Parvovirus B19 or Rubella can cause arthritis, VZV is rarely isolated from joint fluid. * **Blood:** Although a transient viremia occurs during the incubation period, the viral titer in the blood is low and fleeting compared to the high concentration found in skin lesions [1]. **NEET-PG High-Yield Pearls:** * **Tzanck Smear:** A classic bedside test showing **multinucleated giant cells** with **Cowdry Type A** intranuclear inclusion bodies (seen in VZV, HSV-1, and HSV-2) [2]. * **Latency:** VZV remains latent in the **dorsal root ganglia** or cranial nerve ganglia [1]. * **Dermatomal Distribution:** Reactivation (Shingles) typically follows a single unilateral dermatome [4]. * **Gold Standard:** While Tzanck is fast, **PCR** of skin lesion swabs is now the gold standard for definitive diagnosis [2].

Q: Coxsackie B virus causes all except?

Herpangina. **Explanation:** The correct answer is **Herpangina** because it is primarily caused by **Coxsackie A virus**, not Coxsackie B. **1. Why Herpangina is the correct answer:** Herpangina is a febrile illness characterized by vesicular and ulcerative lesions on the posterior pharynx (soft palate, tonsils, and uvula). It is classically associated with **Coxsackie A viruses** (specifically types 1–10, 16, and 22). While both Group A and B are Enteroviruses, Group A typically targets the skin and mucous membranes, whereas Group B tends to target internal organs like the heart, pleura, and pancreas. **2. Analysis of Incorrect Options:** * **Aseptic Meningitis:** Both Coxsackie A and B are leading causes of viral (aseptic) meningitis. It is a common manifestation of Group B infections. * **Myocarditis:** Coxsackie B is the **most common viral cause** of acute myocarditis and pericarditis. It can lead to dilated cardiomyopathy. * **Bornholm Disease:** Also known as "Epidemic Pleurodynia" or the "Devil’s Grip," this condition is characterized by sudden, lancinating chest and abdominal pain due to inflammation of the intercostal muscles. It is almost exclusively caused by **Coxsackie B**. **High-Yield Clinical Pearls for NEET-PG:** * **Coxsackie A:** Think "Sores" (Herpangina, Hand-Foot-Mouth Disease). * **Coxsackie B:** Think "Body" (Myocarditis, Bornholm disease/Pleurodynia, Hepatitis, and even Type 1 Diabetes linkage via pancreatic damage). * **Hand-Foot-Mouth Disease (HFMD):** Most commonly caused by Coxsackie **A16** and Enterovirus 71. * **Rule of Thumb:** If the disease involves the heart or pleura, the answer is almost always Coxsackie B.

Q: Which type of poliovirus is responsible for most epidemics of poliomyelitis?

Type I virus. **Explanation:** Poliovirus is a member of the *Picornaviridae* family (genus *Enterovirus*) and exists in three distinct serotypes: Type 1 (Brunhilde), Type 2 (Lansing), and Type 3 (Leon). **Why Type I is Correct:** **Type I virus** is the most common cause of paralytic poliomyelitis and is responsible for the vast majority of epidemics. It is the most virulent and stable of the three types. Historically, Type I has been the hardest to eradicate from endemic regions due to its high transmissibility and propensity to cause large-scale outbreaks. **Analysis of Incorrect Options:** * **Type II virus:** This was the first serotype to be officially declared eradicated globally (in 2015). While it was highly immunogenic, it was less frequently associated with major epidemics compared to Type I. Most current Type 2 cases are "vaccine-derived" (cVDPV2) rather than wild-type. * **Type III virus:** This type is the least common cause of epidemics. It is, however, the most common cause of **Vaccine-Associated Paralytic Poliomyelitis (VAPP)** in some regions. Wild Poliovirus Type 3 was declared eradicated in 2019. * **Combination of Type II and III:** Epidemics are typically driven by a single dominant strain (historically Type I). A combination of II and III does not reflect the epidemiological reality of wild poliovirus transmission. **High-Yield NEET-PG Pearls:** * **Most common serotype in epidemics:** Type I. * **Most common cause of VAPP:** Type III (followed by Type II). * **Eradication Status:** Wild Poliovirus (WPV) Type 2 and Type 3 are eradicated; only WPV Type 1 remains endemic (primarily in Afghanistan and Pakistan). * **Specimen of choice:** Stool (highest viral shed). * **Culture:** Primary monkey kidney cell lines (shows characteristic "crenation" or rounding of cells).

Q: Which of the following is a primary cell culture?

Chick fibroblast. **Explanation:** Cell cultures are classified into three types based on their origin, chromosomal characteristics, and the number of times they can be subcultured. **1. Why Chick Fibroblast is Correct:** **Chick embryo fibroblast** is a **Primary Cell Culture**. These are derived directly from normal animal or human tissues (e.g., rhesus monkey kidney, human amnion, or chick embryo) by mechanical or enzymatic dissociation. * **Key Feature:** They consist of normal cells with a diploid number of chromosomes. * **Limitation:** They can be subcultured only once or twice before they die out. They are highly useful for the primary isolation of viruses and vaccine production. **2. Analysis of Incorrect Options:** * **B (HeLa) & C (HEp-2):** These are **Continuous Cell Lines** (also known as Immortal Cell Lines). They are derived from cancerous tissues and can be subcultured indefinitely. * **HeLa** is derived from a human cervical carcinoma. * **HEp-2** is derived from a human epithelioma of the larynx. * **D (HL-8):** This is a distractor; however, similar designations like **HL-60** refer to continuous leukemia cell lines. Continuous lines are heteroploid (abnormal chromosome number). **3. Clinical Pearls for NEET-PG:** * **Diplod Cell Strains:** (e.g., **WI-38, MRC-5**) are derived from human fetal lung tissues. They maintain a diploid karyotype and can be subcultured about 50 times. They are the preferred substrate for producing human viral vaccines (e.g., Rubella, Rabies). * **Vero cells:** Derived from African green monkey kidney; these are a common continuous cell line used in microbiology. * **Cytopathic Effect (CPE):** The structural changes in host cells caused by viral invasion, used to identify viruses in these cultures.

Q: Hepatitis B virus (HBV) is associated with all of the following except?

Hepatic adenoma. **Explanation:** The correct answer is **C. Hepatic adenoma**. **1. Why Hepatic Adenoma is the correct answer:** Hepatic adenoma is a **benign** liver tumor primarily associated with **oral contraceptive pill (OCP) use**, anabolic steroid use, or glycogen storage diseases. It is not caused by viral infections. Hepatitis B Virus (HBV) is a known oncogenic virus that integrates into the host genome, leading to malignant transformation rather than benign adenomatous growth. **2. Analysis of Incorrect Options:** * **Hepatic Cancer (Hepatocellular Carcinoma - HCC):** HBV is a major risk factor for HCC. The HBx protein acts as a transcriptional transactivator that disrupts cell cycle control and inhibits p53 (a tumor suppressor gene), directly promoting malignancy. * **Chronic Hepatitis:** Approximately 5–10% of adults and up to 90% of infected neonates fail to clear the surface antigen (HBsAg) within 6 months, leading to chronic hepatitis. * **Cirrhosis:** Chronic inflammation and immune-mediated destruction of hepatocytes lead to extensive fibrosis and regenerative nodules, culminating in cirrhosis. HBV is one of the leading causes of cirrhosis worldwide. **3. NEET-PG High-Yield Pearls:** * **HBV Genome:** It is a partially double-stranded circular DNA virus (Hepadnaviridae). * **Oncogenesis:** HBV can cause HCC **without** preceding cirrhosis (unlike HCV, where cirrhosis is usually a prerequisite). * **Extrahepatic Manifestations:** HBV is strongly associated with **Polyarteritis Nodosa (PAN)** and Membranous Glomerulonephritis. * **Ground Glass Hepatocytes:** A classic histological finding in chronic HBV infection due to the accumulation of HBsAg in the endoplasmic reticulum.

Question 1

Infection with which of the following agents is particularly dangerous for anemic patients?

Accepted Answer

Parvovirus

Answer

Adenovirus

Answer

Cytomegalovirus

Answer

Herpes simplex virus

Question 2

A 27-year-old man develops malaise, fatigue, and loss of appetite three weeks after a meal. He notes passing dark urine. On physical examination, he has mild scleral icterus and right upper quadrant tenderness. Laboratory studies show serum AST of 62 U/L and ALT of 58 U/L. The total bilirubin concentration is 3.9 mg/dL, and the direct bilirubin concentration is 2.8 mg/dL. His symptoms abate over the next 3 weeks. The cause of his illness is most likely related to contaminated food. Which of the following serologic test results is most likely to be positive in this patient?

Accepted Answer

Anti-HAV

Answer

Anti-HBc

Answer

Anti-HBs

Answer

Anti-HCV

Question 3

Hantavirus is an emerging pathogen that is best described by which of the following statements?

Accepted Answer

Influenza-like symptoms are followed rapidly by acute respiratory failure

Answer

Hemolysis is common in infected patients

Answer

It is acquired by inhalation of aerosols of the urine and feces of infected rodents

Answer

Transmission from human to human is common

Question 4

A nurse has been found to be seropositive for both HbsAg and HBeAg. She is suffering from which of the following conditions?

Accepted Answer

Acute Hepatitis B infection

Answer

Concurrent Hepatitis B and Hepatitis E infection

Answer

Chronic Hepatitis B infection

Answer

Past Hepatitis B infection

Question 5

Which of the following is the characteristic site for the detection of Varicella-zoster virus (VZV) in active infection?

Accepted Answer

Skin

Answer

Cervical tissue

Answer

Synovial fluid

Answer

Blood

Question 6

Coxsackie B virus causes all except?

Accepted Answer

Herpangina

Answer

Aseptic meningitis

Answer

Myocarditis

Answer

Bornholm disease

Question 7

Which type of poliovirus is responsible for most epidemics of poliomyelitis?

Accepted Answer

Type I virus

Answer

Type II virus

Answer

Type III virus

Answer

Combination of Type II and Type III viruses

Question 8

Which of the following is a primary cell culture?

Accepted Answer

Chick fibroblast

Answer

Hela

Answer

HEP-2

Answer

HL-8

Question 9

What is the reason why most patients suffering from recurrent herpes labialis rarely give a history of having the acute form of herpetic gingivostomatitis?

Accepted Answer

The primary infection was subclinical

Answer

Etiological agents differ

Answer

The acute form occurs only in severely immunocompromised individuals

Answer

The patient has received antibodies during intrauterine life and the antibodies have persisted

Question 10

Hepatitis B virus (HBV) is associated with all of the following except?

Accepted Answer

Hepatic adenoma

Answer

Hepatic cancer

Answer

Chronic hepatitis

Answer

Cirrhosis

Virology — MCQs

Virology — MCQs

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