Virology Practice Questions

Q: Which of the following is the causative agent of rubella?

Caused by RNA virus of Togavirus family. ***Caused by RNA virus of Togavirus family*** - Rubella, also known as German measles, is caused by a **single-stranded RNA virus** belonging to the **Togaviridae family** (specifically the *Rubivirus* genus). - This classification is important for understanding its replication, transmission, and immune response. *There is no known carrier state for postnatally acquired rubella* - This statement is not the causative agent of rubella; it describes a characteristic of the disease's epidemiology. - While prolonged shedding can occur, a true chronic **carrier state** like that seen in certain other viral infections is not characteristic of rubella. *Rubella vaccine is live attenuated with strain RA 27/3* - This describes the **rubella vaccine**, not the causative agent itself. - The **RA 27/3 strain** refers to the specific attenuated (weakened) virus used in the vaccine to induce active immunity. *Risk of transmission and severity maximum in 1st trimester of pregnancy* - This statement describes a crucial clinical aspect of rubella infection in pregnant women, specifically concerning **congenital rubella syndrome (CRS)**, but it does not identify the causative agent. - The risk of **fetal infection** and severe birth defects is highest when the mother contracts rubella during the **first trimester** of pregnancy.

Q: Which of the following viruses is NOT known to be associated with human cancers?

Parvovirus B-19. ***Parvovirus B-19*** - Parvovirus B-19 is primarily associated with **fifth disease** in children and causes symptoms like rash and anemia, not cancer. - Unlike the other viruses listed, it has no established link to **human malignancies** [2]. *Papilloma virus* - Certain strains of **human papillomavirus (HPV)** are known to cause **cervical** and other cancers, making it a significant carcinogen [1][2]. - HPV is associated with the development of **kinetic lesions** that can progress to cancer. *Hepatitis B virus* - Hepatitis B virus is a well-established cause of **hepatocellular carcinoma** due to chronic liver inflammation and cirrhosis [2][3]. - It can lead to **viral oncogenesis** through integration into the host genome [3]. *Epstein Barr virus* - Epstein Barr virus (EBV) is linked to several cancers, including **Burkitt lymphoma** and **nasopharyngeal carcinoma** [2][4]. - It plays a role in immune evasion leading to **B-cell transformation**, which can result in malignancy [4]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, pp. 334-335. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. (Basic Pathology) introduces the student to key general principles of pathology, both as a medical science and as a clinical activity with a vital role in patient care. Part 2 (Disease Mechanisms) provides fundamental knowledge about the cellular and molecular processes involved in diseases, providing the rationale for their treatment. Part 3 (Systematic Pathology) deals in detail with specific diseases, with emphasis on the clinically important aspects., pp. 219-220. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, pp. 336-337. [4] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, pp. 335-336.

Q: What is the primary disease associated with Enterovirus 71?

Hand, foot, and mouth disease. ***Hand, foot, and mouth disease*** - **Enterovirus 71** is a major causative agent of **hand, foot, and mouth disease (HFMD)**, especially in severe cases involving neurological complications. - HFMD is characterized by **fever**, **oral lesions**, and a **rash** on the hands and feet, particularly common in young children. *Hepatitis E* - **Hepatitis E** is caused by the **Hepatitis E virus (HEV)**, a distinct RNA virus, not an enterovirus. - It primarily causes **acute viral hepatitis**, particularly transmitted via the fecal-oral route. *Hepatitis G* - **Hepatitis G virus (HGV)**, also known as **GBV-C**, is a flavivirus, which is distinct from enteroviruses. - Its clinical significance and role in causing hepatitis are still debated, and it's not a primary cause of symptomatic liver disease. *Hepatitis C* - **Hepatitis C** is caused by the **Hepatitis C virus (HCV)**, an RNA virus belonging to the *Flaviviridae* family, genetically distinct from enteroviruses. - HCV is a major cause of **chronic hepatitis**, cirrhosis, and hepatocellular carcinoma.

Q: Which test is primarily used for the quantification of viral infectivity?

Plaque assay. ***Plaque assay*** - The **plaque assay** directly measures the number of **infectious viral particles** in a sample, expressed as plaque-forming units (PFU) per milliliter. - It involves inoculating host cells with serially diluted virus, leading to localized areas of cell lysis or destruction called **plaques**, which are then counted. *Cytopathic effect* - **Cytopathic effect (CPE)** refers to the visual changes induced in host cells by viral infection, such as cell rounding, lysis, or syncytia formation. - While it indicates an infection is occurring, it does not reliably **quantify** the number of infectious viral particles. *Haemagglutination* - **Hemagglutination assay** measures the ability of certain viruses to agglutinate red blood cells due to binding of viral proteins to receptors on the cell surface. - This method quantifies the **total number of viral particles** (infectious or non-infectious) that possess hemagglutinating activity, not specifically their infectivity. *Electron microscopy* - **Electron microscopy** allows for direct visualization of virus particles and their morphological characteristics. - It can determine the **total number of physical viral particles** in a sample but cannot distinguish between infectious and non-infectious particles.

Q: Fifth disease is caused by which virus?

Parvovirus B19. ***Parvovirus B19*** - **Parvovirus B19** is the sole member of the *Erythrovirus* genus known to cause disease in humans, primarily responsible for **Fifth disease**, also known as **erythema infectiosum**. - This virus targets and replicates in **erythroid progenitor cells**, leading to a characteristic rash and, in some cases, transient aplastic crisis. *Human Papillomavirus (HPV)* - HPV is known to cause **warts** and is a major risk factor for various cancers, including **cervical cancer**, not Fifth disease. - It infects epithelial cells and leads to proliferative lesions, with over 100 different types identified. *Hepatitis Virus* - Hepatitis viruses (e.g., A, B, C, D, E) primarily cause **inflammation of the liver** and are associated with acute or chronic liver disease. - They are not associated with the characteristic rash or symptoms of Fifth disease. *Cytomegalovirus (CMV)* - CMV is a common virus that usually causes **asymptomatic infection** but can lead to severe disease in immunocompromised individuals or newborns. - It is known for causing **congenital infections** and opportunistic infections in transplant recipients, not Fifth disease.

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

Zika virus does not cause microcephaly. ***Zika virus does not cause microcephaly*** - This statement is false because **Zika virus** is well-known for causing **microcephaly** and other severe birth defects in infants whose mothers were infected during pregnancy. - The association between maternal Zika infection and fetal microcephaly has been extensively documented and is one of the most critical public health concerns related to the virus. *Transmitted by Aedes mosquito* - This statement is true; **Aedes aegypti** and **Aedes albopictus** mosquitoes are the primary vectors responsible for transmitting the Zika virus to humans. - These mosquitoes are also known to transmit other arboviruses like **dengue** and **chikungunya**. *Zika is Flavi virus* - This statement is true; Zika virus belongs to the **Flaviridae family** and the *Flavivirus genus*, which also includes dengue, yellow fever, and West Nile viruses. - Members of this family are typically **single-stranded RNA viruses** with an enveloped capsid. *Zika virus cannot be transmitted through breast milk* - This statement is true; while Zika virus RNA has been detected in breast milk, there is currently **no confirmed evidence** of transmission to infants through breastfeeding. - Current guidelines from health organizations generally recommend that mothers in Zika-affected areas continue to breastfeed due to the benefits of breastfeeding outweighing the theoretical risk.

Q: Which of the following serves as the cellular receptor for Epstein-Barr Virus (EBV)?

CD 21. ***CD 21*** - **CD21**, also known as the **complement receptor 2 (CR2)**, is the primary cellular receptor for Epstein-Barr Virus (EBV). - EBV predominantly infects **B lymphocytes** by binding to CD21, allowing viral entry. *CD 20* - **CD20** is a transmembrane protein found on **B-lymphocytes**, but it is **not** the receptor for EBV. - It is often targeted in cancer therapy for B-cell lymphomas (e.g., with **Rituximab**). *CD 22* - **CD22** is an inhibitory co-receptor on B-lymphocytes that **regulates B-cell activation**. - While present on B-cells, it does **not** serve as the entry receptor for EBV. *CD 23* - **CD23** is the **low-affinity IgE receptor (FcεRII)**, found on activated B cells, macrophages, and other immune cells. - It is **not** the receptor used by EBV for cellular entry; rather, it is involved in **IgE-mediated immune responses**.

Q: Dengue fever is caused by:

Flavivirus. ***Flavivirus*** - Dengue fever is caused by the **dengue virus**, which belongs to the **Flaviviridae family** (genus Flavivirus). - There are **four serotypes** of dengue virus (DENV-1, DENV-2, DENV-3, DENV-4), all of which can cause dengue fever. - Flaviviruses are **RNA viruses** transmitted by **arthropod vectors** (primarily *Aedes aegypti* and *Aedes albopictus* mosquitoes). - Other important flaviviruses include **Yellow fever virus**, **Zika virus**, **West Nile virus**, and **Japanese encephalitis virus**. *Orthomyxo virus* - This family includes the **influenza viruses** (influenza A, B, C, D) which cause seasonal flu and pandemic influenza. - They are **segmented RNA viruses** transmitted via **respiratory droplets**, not arthropod vectors. - Characterized by surface proteins **hemagglutinin (H)** and **neuraminidase (N)**. *Paramyxo virus* - This family includes viruses causing **measles**, **mumps**, **parainfluenza**, and **respiratory syncytial virus (RSV)**. - These are **non-segmented negative-sense RNA viruses** transmitted through **respiratory secretions** and close contact. - Not transmitted by arthropod vectors. *Bunya virus* - The **Bunyaviridae family** (now reclassified into multiple families) includes various arboviruses like **Crimean-Congo hemorrhagic fever virus** and **Rift Valley fever virus**. - Also includes **hantaviruses** transmitted by rodents (not arthropods). - While some bunyaviruses cause hemorrhagic fevers, dengue virus specifically belongs to the **Flaviviridae family**, not Bunyaviridae.

Q: Virus lacking hemagglutinin and neuraminidase but having a prominent membrane fusion (F) protein as its major surface glycoprotein is?

Respiratory Syncytial Virus (RSV). ***Respiratory Syncytial Virus (RSV)*** - RSV is characterized by the presence of a **prominent fusion (F) protein** as its major surface glycoprotein, which mediates membrane fusion and viral entry into host cells. - Unlike influenza viruses, RSV **lacks hemagglutinin and neuraminidase proteins**. - The **F protein is the primary virulence factor** and target for antibody-mediated immunity. *Cytomegalovirus (CMV)* - CMV is a **herpesvirus** that does not possess hemagglutinin or neuraminidase. - Its entry mechanism involves **multiple glycoproteins** (gB, gH, gL) that work together for fusion, rather than a single prominent F protein like RSV. *Herpes Simplex Virus (HSV)* - HSV is another **herpesvirus** that utilizes **various glycoproteins** (gB, gD, gH, gL) working in concert for binding and membrane fusion. - It **lacks hemagglutinin and neuraminidase** but does not have a single prominent fusion protein. *Epstein-Barr Virus (EBV)* - EBV, a member of the **herpesvirus family**, also does not have hemagglutinin or neuraminidase. - Its entry involves **specific glycoproteins** (gH, gL, gp42, gB) that are responsible for receptor binding and membrane fusion in a coordinated manner.

Question 1

Which of the following is the causative agent of rubella?

Accepted Answer

Caused by RNA virus of Togavirus family

Answer

Risk of transmission and severity maximum in 1st trimester of pregnancy

Answer

Rubella vaccine is live attenuated with strain RA 27/3

Answer

There is no known carrier state for postnatally acquired rubella

Question 2

Which of the following statements about influenza is true?

Accepted Answer

Type-A virus can cause pandemics

Answer

Incubation period is 18-72 hours

Answer

Type-A virus is associated with Reye's syndrome when aspirin is used

Answer

Most infections are subclinical or mild

Question 3

Which of the following viruses is NOT known to be associated with human cancers?

Accepted Answer

Parvovirus B-19

Answer

Hepatitis B virus

Answer

Human Papillomavirus

Answer

Epstein-Barr virus

Question 4

What is the primary disease associated with Enterovirus 71?

Accepted Answer

Hand, foot, and mouth disease

Answer

Hepatitis E

Answer

Hepatitis G

Answer

Hepatitis C

Question 5

Which test is primarily used for the quantification of viral infectivity?

Accepted Answer

Plaque assay

Answer

Haemagglutination

Answer

Cytopathic effect

Answer

Electron microscopy

Question 6

Fifth disease is caused by which virus?

Accepted Answer

Parvovirus B19

Answer

Human Papillomavirus (HPV)

Answer

Hepatitis Virus

Answer

Cytomegalovirus (CMV)

Question 7

Which of the following statements about Zika virus is false?

Accepted Answer

Zika virus does not cause microcephaly

Answer

Transmitted by Aedes mosquito

Answer

Zika is Flavi virus

Answer

Zika virus cannot be transmitted through breast milk

Question 8

Which of the following serves as the cellular receptor for Epstein-Barr Virus (EBV)?

Accepted Answer

CD 21

Answer

CD 22

Answer

CD 20

Answer

CD 23

Question 9

Dengue fever is caused by:

Accepted Answer

Flavivirus

Answer

Orthomyxo virus

Answer

Paramyxo virus

Answer

Bunya virus

Question 10

Virus lacking hemagglutinin and neuraminidase but having a prominent membrane fusion (F) protein as its major surface glycoprotein is?

Accepted Answer

Respiratory Syncytial Virus (RSV)

Answer

Herpes Simplex Virus (HSV)

Answer

Cytomegalovirus (CMV)

Answer

Epstein-Barr Virus (EBV)

Virology — MCQs

Virology — MCQs

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