Virology Practice Questions

Q: Owl's eye appearance inclusion bodies can be demonstrated in the diagnosis of which human herpesvirus (HHV) infection?

HHV-5 (Cytomegalovirus). **Explanation:** The correct answer is **HHV-5 (Cytomegalovirus)**. **Why HHV-5 is correct:** Cytomegalovirus (CMV) infection is characterized by the formation of massive cellular enlargement (cytomegaly). The hallmark histopathological finding is the presence of large, **basophilic intranuclear inclusion bodies** surrounded by a clear halo, extending to the nuclear membrane. This specific morphology resembles an **"Owl’s eye."** These inclusions represent areas of active viral replication and are typically seen in epithelial cells of the renal tubules, bile ducts, or salivary glands. **Why other options are incorrect:** * **HHV-1 (Herpes Simplex Virus-1):** Characterized by **Cowdry Type A** inclusions (eosinophilic intranuclear inclusions) and multinucleated giant cells (Tzanck smear), but not the "Owl's eye" appearance. * **HHV-6 (Roseolovirus):** Primarily causes Roseola Infantum (Exanthem Subitum). While it infects T-cells, it does not produce the classic "Owl's eye" inclusions. * **HHV-4 (Epstein-Barr Virus):** Associated with infectious mononucleosis and various malignancies. The diagnostic hallmark is **atypical lymphocytes (Downey cells)** in the peripheral blood, not intranuclear inclusions. Note: "Owl's eye" nuclei are seen in Reed-Sternberg cells of Hodgkin Lymphoma (associated with EBV), but these are nucleoli, not viral inclusion bodies. **High-Yield Clinical Pearls for NEET-PG:** * **CMV** is the most common cause of congenital malformation (presents with periventricular calcifications and microcephaly). * In HIV patients, CMV is a major cause of **retinitis** ("pizza-pie" appearance) and **colitis**. * **Drug of choice:** Ganciclovir (Valganciclovir for prophylaxis). * **Culture:** CMV grows best in human fibroblast cell lines (demonstrating "shell vial" entry).

Q: Which virus families possess double-stranded DNA in four different isomers?

Herpesviruses. **Explanation:** The correct answer is **Herpesviruses**. This is a high-yield molecular biology concept frequently tested in NEET-PG. **Why Herpesviruses?** The genome of Herpesviruses (such as HSV and CMV) consists of a linear, double-stranded DNA molecule. This genome is organized into two components: **Unique Long (UL)** and **Unique Short (US)** regions. Each of these regions is flanked by inverted repeat sequences. Because these segments can invert their orientation independently of one another, the genome can exist in **four different structural isomers** (topoisomers). This genomic flexibility is a hallmark of the *Herpesviridae* family. **Analysis of Incorrect Options:** * **Poxviruses (Option A):** While they are dsDNA viruses, their genome is a single, continuous linear molecule with covalently closed ends (hairpin loops). They do not undergo the specific segmental inversion required to form four isomers. * **Rabiesviruses (Option B):** These belong to the *Rhabdoviridae* family and possess a **negative-sense, single-stranded RNA (-ssRNA)** genome, not DNA. * **Orthomyxoviruses (Option D):** These (e.g., Influenza) possess a **segmented, negative-sense, single-stranded RNA** genome. While they have segments, they do not have dsDNA isomers. **High-Yield Clinical Pearls for NEET-PG:** * **Herpesvirus Structure:** They are the only viruses that possess an **envelope**, a **tegument** (space between capsid and envelope), and a dsDNA genome. * **Replication:** Unlike most DNA viruses that replicate in the nucleus, **Poxviruses** are the exception—they replicate in the **cytoplasm** because they carry their own DNA-dependent RNA polymerase. * **Isomer Significance:** The four isomers of Herpesviruses are functionally equivalent; all four are infectious and capable of producing progeny.

Q: Which of the following statements about hepatitis G virus is false?

It responds to lamivudine therapy.. **Explanation:** The Hepatitis G Virus (HGV), also known as **GB virus C (GBV-C)**, is a member of the *Flaviviridae* family. The correct answer is **D** because HGV is an **RNA virus**, and **Lamivudine** is a nucleoside analog that inhibits reverse transcriptase, primarily used for DNA viruses like Hepatitis B (HBV) or retroviruses like HIV. It has no therapeutic role in HGV infection. **Analysis of Options:** * **Option A:** HGV was independently discovered and named GB virus C (after surgeon G. Barker). Both terms are used interchangeably in medical literature. * **Option B:** It is a positive-sense, single-stranded **RNA virus**. Its primary mode of transmission is parenteral (blood-borne), similar to HCV and HBV. * **Option C:** Due to shared transmission routes (IV drug use, blood transfusions), HGV is frequently found as a co-infection with **HCV** (up to 10-20% of cases) and HIV. **High-Yield Clinical Pearls for NEET-PG:** 1. **Pathogenicity:** Despite its name, HGV is generally considered **non-pathogenic**. It does not cause acute or chronic hepatitis, nor does it worsen the clinical course of HCV or HBV. 2. **HIV Benefit:** A high-yield fact is that HGV/GBV-C co-infection in **HIV patients** is associated with **slower disease progression** and improved survival rates, possibly due to interference with HIV entry into CD4 cells. 3. **Diagnosis:** It is diagnosed via **RT-PCR** for HGV RNA; there is no routine serological test used in clinical practice.

Q: What is the term for the virus that causes rabies in humans?

Street virus. **Explanation:** The classification of the Rabies virus into "Street" and "Fixed" strains is a fundamental concept in virology, primarily based on their source and biological behavior. **1. Why "Street Virus" is correct:** The term **Street virus** refers to the rabies virus as it exists in nature, isolated from naturally infected animals (like dogs, bats, or cats) or humans. It is characterized by a long and variable incubation period (usually 1–3 months) and the consistent production of **Negri bodies** (intracytoplasmic inclusion bodies) in the brain tissue. This is the strain responsible for causing clinical rabies in humans. **2. Why the other options are incorrect:** * **Fixed Virus (Option C):** This is a street virus that has been modified by serial passage through the brains of laboratory animals (usually rabbits). This process "fixes" the incubation period to a short, predictable duration (4–6 days). Crucially, fixed viruses are **not** found in nature, do not produce Negri bodies, and are used primarily for vaccine production. * **Wild Virus (Option A):** While "wild" is a general term used for viruses found in nature (like wild-type Polio), it is not the specific technical nomenclature used in Rabies virology to differentiate between natural and laboratory strains. **High-Yield Clinical Pearls for NEET-PG:** * **Negri Bodies:** Pathognomonic for rabies; most commonly found in the **Hippocampus (Ammon’s horn)** and **Cerebellum (Purkinje cells)**. They are absent in infections caused by the Fixed virus. * **Genome:** Negative-sense, single-stranded RNA (ssRNA), bullet-shaped symmetry (Rhabdoviridae). * **Prophylaxis:** Post-exposure prophylaxis (PEP) includes wound cleaning, Rabies vaccine (Active), and Rabies Immunoglobulin (Passive). * **Antigenicity:** Both Street and Fixed viruses share the same surface G-protein antigens, which is why vaccines made from fixed strains protect against street virus exposure.

Q: Giant cell (Hecht's) pneumonia is due to which of the following?

Measles virus. **Explanation:** **Giant cell pneumonia (Hecht’s pneumonia)** is a severe, often fatal interstitial pneumonia caused by the **Measles virus** (Rubeola). It typically occurs in immunocompromised individuals (e.g., those with leukemia, HIV, or severe malnutrition) who fail to develop the characteristic maculopapular rash due to impaired T-cell mediated immunity. 1. **Why Measles is correct:** The hallmark of Measles infection is the formation of **Warthin-Finkeldey giant cells**—large multinucleated cells with eosinophilic intranuclear and intracytoplasmic inclusion bodies. In the lungs, these cells lead to progressive alveolar damage, known as Hecht’s pneumonia. 2. **Why other options are incorrect:** * **CMV:** Causes interstitial pneumonia in transplant recipients, characterized by "Owl’s eye" intranuclear inclusions, but not Hecht’s giant cell pneumonia. * **Malaria:** Can cause Acute Respiratory Distress Syndrome (ARDS) in severe cases (especially *P. falciparum*), but does not produce giant cell pathology. * **Pneumocystis carinii (jirovecii):** Causes PCP pneumonia in HIV patients, characterized by a "crushed ping-pong ball" appearance on silver stain and "foamy" alveolar exudates, not multinucleated giant cells. **High-Yield Clinical Pearls for NEET-PG:** * **Warthin-Finkeldey cells:** Pathognomonic for Measles; found in lymphoid tissue and lungs. * **Koplik’s spots:** Small white spots on buccal mucosa (opposite lower 2nd molars); the earliest clinical sign of Measles. * **Vitamin A:** Supplementation reduces morbidity and mortality in children with Measles. * **SSPE (Subacute Sclerosing Panencephalitis):** A late neurological complication caused by a persistent mutant measles virus.

Q: Which of the following viruses has negative-sense RNA?

Rabies. **Explanation:** The classification of RNA viruses based on their genomic polarity is a high-yield topic for NEET-PG. RNA viruses are categorized as **Positive-sense (+ssRNA)**, which can be directly translated into proteins by host ribosomes, or **Negative-sense (-ssRNA)**, which must first be transcribed into positive-sense mRNA by a viral RNA-dependent RNA polymerase (RdRp). **Correct Answer: A. Rabies** Rabies virus belongs to the **Rhabdoviridae** family. All Rhabdoviruses possess a single-stranded, negative-sense RNA genome. Because the genome cannot be directly translated, the virion must carry its own RdRp enzyme to initiate the infection cycle within the host cell. **Incorrect Options:** * **B. Reovirus:** These are unique because they possess **double-stranded RNA (dsRNA)**. They are the only medically important dsRNA viruses (e.g., Rotavirus). * **C. Coronavirus:** These are **positive-sense (+ssRNA)** viruses. They have the largest genomes among RNA viruses and are enveloped with a helical nucleocapsid. * **D. Calicivirus:** These are **positive-sense (+ssRNA)**, non-enveloped viruses (e.g., Norovirus). **High-Yield Clinical Pearls for NEET-PG:** * **Mnemonic for Negative-sense RNA viruses:** "**P**aired **O**ld **B**unny **F**ights **R**eally **A**musing **M**onsters" (**P**aramyxo, **O**rthomyxo, **B**unya, **F**ilo, **R**habdo, **A**rena, **M**yxo). * **Rabies Key Features:** Bullet-shaped morphology, Negri bodies (intracytoplasmic inclusions in Hippocampus/Purkinje cells), and centripetal spread via retrograde axonal transport. * All negative-sense RNA viruses are **enveloped** and carry their own **RNA polymerase**.

Q: Guarnieri's body is seen in which of the following conditions?

Smallpox. **Explanation:** **Guarnieri bodies** are the hallmark histopathological finding in **Smallpox** (Variola virus) and Vaccinia virus infections. These are **intracytoplasmic, eosinophilic inclusion bodies** that represent "viral factories" where DNA replication and assembly occur. Since Poxviruses are unique among DNA viruses because they replicate entirely within the cytoplasm rather than the nucleus, they leave these distinct cytoplasmic imprints. **Analysis of Options:** * **Smallpox (Correct):** Guarnieri bodies are specific to the Poxvirus family. They are found in the epithelial cells of the skin in Smallpox patients. * **Chickenpox (Incorrect):** Caused by the Varicella-Zoster Virus (a Herpesvirus). It produces **Cowdry Type A** inclusion bodies, which are **intranuclear** and eosinophilic, often associated with multinucleated giant cells (Tzanck cells). * **Rubella (Incorrect):** A Togavirus that typically does not produce characteristic diagnostic inclusion bodies like Pox or Herpes viruses. * **Measles (Incorrect):** Caused by a Paramyxovirus. It is characterized by **Warthin-Finkeldey giant cells** and produces both **intracytoplasmic and intranuclear** inclusion bodies (Cowdry type A). **High-Yield NEET-PG Pearls:** * **Poxvirus:** Largest DNA virus; replicates in the **cytoplasm** (exception to the rule). * **Molluscum Contagiosum:** Another Poxvirus that shows **Henderson-Patterson bodies** (large, eosinophilic cytoplasmic inclusions). * **Negri Bodies:** Intracytoplasmic inclusions seen in **Rabies** (Hippocampus/Purkinje cells). * **Owl’s Eye Appearance:** Intranuclear inclusions seen in **CMV**. * **Torres Bodies:** Acidophilic cytoplasmic inclusions seen in **Yellow Fever**.

Q: Which of the following viruses has double-stranded nucleic acid in its genome?

Poxviruses and Reoviruses. ### Explanation The classification of viruses based on their genomic structure is a high-yield topic for NEET-PG. Most DNA viruses are double-stranded (dsDNA), while most RNA viruses are single-stranded (ssRNA). However, there are notable exceptions that are frequently tested. **1. Why Option C is Correct:** * **Poxviruses:** These are the largest and most complex **dsDNA** viruses. Unlike most DNA viruses that replicate in the nucleus, Poxviruses replicate in the cytoplasm because they carry their own DNA-dependent RNA polymerase. * **Reoviruses:** This family (including *Rotavirus*) is the primary exception to the rule for RNA viruses, as they possess a **segmented dsRNA** genome. **2. Why Other Options are Incorrect:** * **Parvoviruses (Options A & B):** These are the smallest DNA viruses and are unique because they have a **ssDNA** genome (the "exception" to the dsDNA rule for DNA viruses). * **Orthomyxoviruses (Options A & D):** This family (including *Influenza*) consists of **ssRNA** viruses with a segmented genome. **3. High-Yield Clinical Pearls for NEET-PG:** * **DNA Exceptions:** All DNA viruses are dsDNA **except Parvoviridae** (ssDNA). All DNA viruses are icosahedral **except Poxviridae** (complex/brick-shaped). * **RNA Exceptions:** All RNA viruses are ssRNA **except Reoviridae** (dsRNA). * **Segmented Genomes:** Remember the mnemonic **BOAR** (Bunyavirus, Orthomyxovirus, Arenavirus, Reovirus). These viruses can undergo genetic reassortment, leading to antigenic shifts. * **Replication Site:** All DNA viruses replicate in the nucleus **except Poxvirus**. All RNA viruses replicate in the cytoplasm **except Influenza and Retroviruses**.

Question 1

Owl's eye appearance inclusion bodies can be demonstrated in the diagnosis of which human herpesvirus (HHV) infection?

Accepted Answer

HHV-5 (Cytomegalovirus)

Answer

HHV-1

Answer

HHV-6

Answer

HHV-4 (Epstein-Barr virus)

Question 2

Which virus families possess double-stranded DNA in four different isomers?

Accepted Answer

Herpesviruses

Answer

Poxviruses

Answer

Rabiesviruses

Answer

Orthomyxoviruses

Question 3

Which of the following statements about hepatitis G virus is false?

Accepted Answer

It responds to lamivudine therapy.

Answer

It is also called GB virus.

Answer

It is a blood-borne RNA virus.

Answer

It is mostly found co-infecting with hepatitis C virus.

Question 4

Which of the following statements regarding HIV infection is true?

Accepted Answer

Following needle stick injury, infectivity is reduced by the administration of nucleoside analogues.

Answer

CD4 counts are the best predictors of disease progression.

Answer

Infected T cells survive for a month in infected patients.

Answer

In the latent phase, HIV has minimal replication.

Question 5

What is the term for the virus that causes rabies in humans?

Accepted Answer

Street virus

Answer

Wild virus

Answer

Fixed virus

Answer

All of the above

Question 6

Giant cell (Hecht's) pneumonia is due to which of the following?

Accepted Answer

Measles virus

Answer

Cytomegalovirus (CMV)

Answer

Malaria parasite

Answer

Pneumocystis carinii

Question 7

A 23-year-old woman develops vesicular lesions on an erythematous base on her vulvar area. She has tender lymphadenopathy and dysuria. Which of the following is the most likely causative organism?

Accepted Answer

herpes simplex virus type 2 (HSV-2)

Answer

cytomegalovirus (CMV)

Answer

gonococcus

Answer

Treponema pallidum

Question 8

Which of the following viruses has negative-sense RNA?

Accepted Answer

Rabies

Answer

Reovirus

Answer

Coronavirus

Answer

Calicivirus

Question 9

Guarnieri's body is seen in which of the following conditions?

Accepted Answer

Smallpox

Answer

Chickenpox

Answer

Rubella

Answer

Measles

Question 10

Which of the following viruses has double-stranded nucleic acid in its genome?

Accepted Answer

Poxviruses and Reoviruses

Answer

Orthomyxoviruses and Parvoviruses

Answer

Poxviruses and Parvoviruses

Answer

Orthomyxoviruses and Reoviruses

Virology — MCQs

Virology — MCQs

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