Virology — MCQs
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Rubella is caused by
A neonate was found to have cataract, deafness and cardiac defects. Which group of viruses was the mother infected with?
A patient with HIV presents with extensive anogenital warts. Which HPV types are most commonly associated with malignant transformation in this setting?
What is not true regarding Zika Virus?
Which virus is NOT associated with human cancer?
Asymptomatic hepatitis B is common in 2-3% of the normal population, but there is increased risk of progression to hepatocellular carcinoma. Why?
SD plasma destroys lipid-enveloped viruses. On SD plasma transfusion, which of the following infections is the likely possibility?
Which organism is most associated with neonatal meningitis and skin rash?
In the absence of proper viral transport media, which of the following might be used as an alternative for tissue preservation in virology studies?
Which of the following mechanisms is characteristic of HIV as a retrovirus after it enters the host cell?
Virology Indian Medical PG Practice Questions and MCQs
Question 1291: Rubella is caused by
- A. Paramyxovirus
- B. Orthomyxovirus
- C. Togavirus (Correct Answer)
- D. Flavivirus
Explanation: ***Correct Answer: Togavirus*** - Rubella virus is classified under the genus *Rubivirus* within the family **Togaviridae** - Togaviruses are **enveloped, positive-sense, single-stranded RNA viruses** - Rubella causes German measles, characterized by mild fever and maculopapular rash - Important for congenital rubella syndrome when infection occurs during pregnancy *Incorrect: Paramyxovirus* - This family includes viruses like **measles (rubeola)** and **mumps** - Paramyxoviruses are enveloped, negative-sense, single-stranded RNA viruses - Different structural and genetic characteristics from rubella virus *Incorrect: Orthomyxovirus* - This family primarily consists of **influenza viruses** (types A, B, and C) - Orthomyxoviruses are enveloped, **negative-sense, segmented** RNA viruses - The segmented genome distinguishes them from rubella virus *Incorrect: Flavivirus* - This family includes **dengue virus**, **yellow fever virus**, and **Zika virus** - While flaviviruses are also enveloped, positive-sense, single-stranded RNA viruses, they belong to the family *Flaviviridae*, not Togaviridae - Different envelope proteins and replication strategies distinguish them from rubella virus
Question 1292: A neonate was found to have cataract, deafness and cardiac defects. Which group of viruses was the mother infected with?
- A. Togaviridae family (includes Rubella virus) (Correct Answer)
- B. Flaviviridae family (includes Zika virus)
- C. Bunyaviridae family (includes Rift Valley fever virus)
- D. Arenaviridae family (includes Lassa fever virus)
Explanation: ***Togaviridae family (includes Rubella virus)*** - The classic triad of **congenital rubella syndrome (CRS)** includes **cataracts**, **deafness**, and **cardiac defects** (e.g., patent ductus arteriosus, pulmonary artery stenosis). - Rubella virus is a member of the **Togaviridae family** and causes significant fetal damage if the mother is infected during the first trimester. *Flaviviridae family (includes Zika virus)* - While congenital Zika syndrome can cause severe birth defects, it is primarily associated with **microcephaly**, intracranial calcifications, and ocular abnormalities, not typically the classic rubella triad. - **Deafness** and **linear cataracts** are not characteristic features of congenital Zika infection. *Bunyaviridae family (includes Rift Valley fever virus)* - Rift Valley fever virus is primarily transmitted by mosquitoes and causes **febrile illness** in humans and livestock, with potential for **hemorrhagic fever** or **encephalitis**. - It is not known to cause congenital abnormalities resembling cataracts, deafness, and cardiac defects in neonates. *Arenaviridae family (includes Lassa fever virus)* - Lassa fever virus causes a severe **hemorrhagic fever** in humans, primarily through contact with infected rodents or person-to-person transmission. - It is not associated with congenital malformations such as cataracts, deafness, and cardiac defects.
Question 1293: A patient with HIV presents with extensive anogenital warts. Which HPV types are most commonly associated with malignant transformation in this setting?
- A. Types 42 and 43
- B. Types 31 and 33
- C. Types 16 and 18 (Correct Answer)
- D. Types 6 and 11
Explanation: ***Types 16 and 18*** - **HPV types 16 and 18** are considered **high-risk** and are responsible for the majority of HPV-related cancers, including cervical, anal, and oropharyngeal cancers. - In HIV-positive individuals, the risk of malignant transformation from HPV infection is significantly increased due to **immunocompromise**. *Types 42 and 43* - **HPV types 42 and 43** are classified as **low-risk** HPV types. - They are primarily associated with **benign anogenital warts** and rarely cause malignant transformation. *Types 31 and 33* - **HPV types 31 and 33** are also considered **high-risk** types and can cause malignant transformation. - However, **types 16 and 18** are more frequently associated with HPV-related cancers than types 31 and 33. *Types 6 and 11* - **HPV types 6 and 11** are **low-risk** types and are the primary cause of **genital warts (condyloma acuminata)**. - While they can cause extensive warts, they have a very low potential for malignant transformation.
Question 1294: What is not true regarding Zika Virus?
- A. Belong to family flaviviridae
- B. Possibly can cause microcephaly
- C. Transmission happens by Mosquitoes
- D. Not transmitted from mother to newborn (Correct Answer)
Explanation: ***Not transmitted from mother to newborn*** ✓ - This is the **correct answer** because this statement is **FALSE**. - Zika virus **CAN be transmitted** from a pregnant mother to her unborn child (vertical transmission), leading to severe birth defects. - **Vertical transmission** from mother to fetus is a well-documented and concerning route of Zika virus spread, particularly associated with congenital Zika syndrome. *Belong to family flaviviridae* - This statement is **TRUE**, so it is not the correct answer. - The Zika virus is indeed part of the **Flaviviridae family**, which also includes dengue, yellow fever, West Nile, and Japanese encephalitis viruses. - This classification is based on its structure as a positive-sense single-stranded **RNA virus**. *Possibly can cause microcephaly* - This statement is **TRUE**, so it is not the correct answer. - Zika virus infection during pregnancy is strongly linked to **microcephaly** and other severe congenital abnormalities (congenital Zika syndrome). - This neurological complication is the most concerning outcome of **prenatal Zika exposure**. *Transmission happens by Mosquitoes* - This statement is **TRUE**, so it is not the correct answer. - The primary mode of transmission for Zika virus is through the bite of infected **Aedes species mosquitoes**, particularly *Aedes aegypti* and *Aedes albopictus*. - These mosquitoes are also vectors for dengue, chikungunya, and yellow fever. Note: Zika can also be transmitted sexually and through blood transfusion.
Question 1295: Which virus is NOT associated with human cancer?
- A. HPV
- B. Measles virus (Correct Answer)
- C. HHV-8
- D. EBV
Explanation: ***Measles virus*** - The **measles virus** (rubeola) is primarily known for causing acute febrile illness with a characteristic rash and is not recognized as an **oncogenic virus** in humans. - While it can cause significant morbidity and mortality, particularly in unvaccinated populations, its mode of action does not involve **cellular transformation** or sustained **oncogene expression**. *HPV* - **Human Papillomavirus (HPV)**, particularly high-risk types like HPV-16 and HPV-18, is a well-established cause of **cervical cancer**, as well as other anogenital and oropharyngeal cancers. - HPV oncogenes, **E6** and **E7**, interfere with tumor suppressor proteins like p53 and Rb, promoting uncontrolled cell growth. *HHV-8* - **Human Herpesvirus 8 (HHV-8)**, also known as Kaposi's sarcoma-associated herpesvirus (KSHV), is the causative agent of **Kaposi's sarcoma**, a vascular tumor. - HHV-8 is also associated with primary effusion lymphoma and multicentric Castleman's disease due to its **latency-associated nuclear antigen (LANA)** and other viral oncogenes. *EBV* - **Epstein-Barr Virus (EBV)** is strongly linked to several human cancers, including **Burkitt's lymphoma**, **nasopharyngeal carcinoma**, and Hodgkin's lymphoma. - EBV transforms B lymphocytes through the expression of latency genes such as **LMP1** and **EBNA2**, which modulate cell growth and survival pathways.
Question 1296: Asymptomatic hepatitis B is common in 2-3% of the normal population, but there is increased risk of progression to hepatocellular carcinoma. Why?
- A. Integration of viral DNA with host DNA (Correct Answer)
- B. High rate of proliferation of virus
- C. Inability to induce inflammation to remove the organism
- D. High level of transaminases
Explanation: ***Integration of viral DNA with host DNA*** - **Hepatitis B virus (HBV)** is a DNA virus that can integrate its DNA into the host hepatocyte genome, leading to **genomic instability** and potentially activating proto-oncogenes or disrupting tumor suppressor genes. - This integration, along with chronic inflammation and repair, is a key mechanism driving the progression to **hepatocellular carcinoma (HCC)** even in asymptomatic carriers. *High rate of proliferation of virus* - While active viral replication (high viral load) is a risk factor for liver damage and HCC, the *rate of proliferation* itself isn't the primary direct cause of carcinogenesis in asymptomatic carriers. - The direct mechanism leading to malignancy is more closely linked to how the virus interacts with the host genome rather than just its abundance. *Inability to induce inflammation to remove the organism* - An inability to clear the virus and a persistent **immune response** actually contribute to chronic inflammation, which is a significant factor in HCC development. However, this is not the most direct reason for the **oncogenic potential** of HBV itself. - While a robust immune response can cause liver damage, the *lack* of one doesn't directly explain the carcinogenic potential; rather, it leads to persistence and chronic disease. *High level of transaminases* - **Elevated transaminase levels** (like ALT and AST) are indicators of hepatocyte damage and inflammation, not a direct cause of liver cancer. - While chronic elevation suggests ongoing liver injury and increased risk, this is a marker of disease activity, not the fundamental mechanism of oncogenesis.
Question 1297: SD plasma destroys lipid-enveloped viruses. On SD plasma transfusion, which of the following infections is the likely possibility?
- A. HBV
- B. HCV
- C. HIV
- D. HAV (Correct Answer)
Explanation: ***HAV*** - **Single-stranded non-enveloped RNA virus** of the Picornaviridae family, which means it lacks a **lipid envelope**. - As SD plasma therapy **destroys lipid-enveloped viruses,** HAV would likely persist and cause infection. *HBV* - **HBV** (Hepatitis B Virus) is a **lipid-enveloped DNA virus**. - SD plasma processing effectively **inactivates enveloped viruses** like HBV, making transfusion-associated infection unlikely. *HCV* - **HCV** (Hepatitis C Virus) is a **lipid-enveloped RNA virus**. - Like other enveloped viruses, HCV would be **inactivated by SD plasma processing**, thus reducing the risk of transmission. *HIV* - **HIV** (Human Immunodeficiency Virus) is a **lipid-enveloped RNA virus**. - **SD plasma treatment** is highly effective in inactivating HIV due to its **lipid envelope**, making transmission unlikely through this product.
Question 1298: Which organism is most associated with neonatal meningitis and skin rash?
- A. VZV
- B. Group B Streptococcus (GBS)
- C. HSV-2 (Correct Answer)
- D. Enterovirus 71
Explanation: ***HSV-2*** - **Neonatal herpes simplex virus (HSV)** infection, often caused by HSV-2 acquired during vaginal delivery, can manifest with **meningitis** and characteristic **skin vesicles** or a rash. - The rash typically presents as clustered **vesicles on an erythematous base** and can be widespread, making it a key diagnostic clue alongside neurological symptoms. *VZV* - **Varicella-zoster virus (VZV)** can cause neonatal varicella, which presents with a rash but **meningitis** is a much less common complication, typically associated with more severe disseminated disease. - The rash of neonatal varicella usually appears as **macules, papules, vesicles, and scabs** in various stages of healing, rather than the clustered vesicles seen in HSV. *Group B Streptococcus (GBS)* - **GBS** is a leading cause of **neonatal meningitis** and sepsis, but it typically does **not cause a skin rash** in affected infants. - While GBS can cause systemic signs of infection and neurological symptoms, cutaneous manifestations are not characteristic. *Enterovirus 71* - **Enterovirus 71** is known to cause hand, foot, and mouth disease, which includes a **rash** and can, in severe cases, cause **meningitis** or encephalitis. - However, the rash is typically maculopapular or vesicular on the palms, soles, and buttocks, and this association is less common for neonatal meningitis with widespread skin findings compared to HSV.
Question 1299: In the absence of proper viral transport media, which of the following might be used as an alternative for tissue preservation in virology studies?
- A. 50% glycerine (Correct Answer)
- B. Phosphate-buffered saline
- C. Formalin
- D. Skimmed milk
Explanation: ***50% glycerine*** - **Glycerine (glycerol)** acts as a cryoprotectant, preventing ice crystal formation and preserving **viral infectivity** by maintaining cellular integrity during storage. - It is a well-recognized alternative to **viral transport media (VTM)** for tissue preservation, especially for transport of specimens to virology laboratories when VTM is unavailable. - Commonly used at **50% concentration in buffered saline** for preserving viral specimens for culture. *Skimmed milk* - **Skimmed milk** has been used historically as a viral transport medium due to its protein content which can help stabilize some viruses. - However, it is **less reliable** than glycerol-based solutions and may support bacterial growth, limiting its utility for extended preservation. - Not commonly recommended in modern virology practice due to better alternatives. *Phosphate-buffered saline* - **Phosphate-buffered saline (PBS)** is a balanced salt solution that maintains pH and osmolarity, but it lacks the necessary components to stabilize viruses over time. - **PBS** does not contain cryoprotectants or protein stabilizers, making it unsuitable for long-term viral preservation, though it may be used for very short-term transport. *Formalin* - **Formalin** is a fixative used for tissue preservation in histopathology, which denatures proteins and nucleic acids, thereby **inactivating viruses**. - It permanently alters viral structures and renders them unsuitable for viability studies, culture, or most molecular diagnostics requiring intact viral particles.
Question 1300: Which of the following mechanisms is characteristic of HIV as a retrovirus after it enters the host cell?
- A. It integrates into the host genome after entry.
- B. It uses reverse transcriptase after entry to convert RNA to DNA. (Correct Answer)
- C. It binds to CD4 via gp120.
- D. It uses CCR5 co-receptor for entry into host cells.
Explanation: ***It uses reverse transcriptase after entry to convert RNA to DNA.*** - After HIV enters a host cell, its **single-stranded RNA genome** is converted into **double-stranded DNA** by the enzyme **reverse transcriptase**. - This is the **defining characteristic** of retroviruses like HIV, distinguishing them from other viruses. - This reverse transcription step is essential before the viral DNA can integrate into the host genome. *It integrates into the host genome after entry.* - While integration is crucial for HIV's lifecycle, this occurs **after reverse transcription** and is not unique to retroviruses. - Many other viruses (e.g., herpesviruses, adenoviruses) can also integrate into host genomes without being retroviruses. *It binds to CD4 via gp120.* - This describes the **entry mechanism**, which occurs **before** the virus enters the cell, not after entry. - The question specifically asks about mechanisms after cellular entry. *It uses CCR5 co-receptor for entry into host cells.* - Like CD4 binding, CCR5 co-receptor use is part of the **entry process**, not a post-entry mechanism. - Additionally, not all HIV strains use CCR5; some use CXCR4 (X4-tropic strains).
Practice by Chapter
Virus Structure and Classification
Practice Questions
Viral Replication
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Pathogenesis of Viral Infections
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DNA Viruses: Herpesviruses
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DNA Viruses: Poxviruses and Adenoviruses
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Hepatitis Viruses
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RNA Viruses: Orthomyxoviruses
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RNA Viruses: Paramyxoviruses
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Enteroviruses and Rhinoviruses
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Arboviruses
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HIV and Retroviruses
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Oncogenic Viruses
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