Virology Practice Questions

Q: Which paramyxovirus lacks hemagglutinin and neuraminidase but has fusion (F) and attachment (G) proteins?

RSV. ***RSV*** - **Respiratory Syncytial Virus (RSV)** is unique among paramyxoviruses because it **lacks hemagglutinin and neuraminidase** proteins. - Instead, it primarily relies on its **fusion (F) protein** for cell entry and syncytia formation, and an **attachment (G) protein** for binding to host cells. *CMV* - **Cytomegalovirus (CMV)** is a **herpesvirus**, not a paramyxovirus, and therefore has a different array of envelope glycoproteins (gB, gH, gL, gO) essential for cell entry and immune evasion. - It does not possess hemagglutinin, neuraminidase, or the specific F and G proteins characteristic of paramyxoviruses. *HSV* - **Herpes Simplex Virus (HSV)** is also a **herpesvirus**, distinct from paramyxoviruses in its genomic structure and envelope protein composition. - Its envelope contains various glycoproteins, such as **gB, gC, gD, gE, gH, and gL**, which mediate attachment, entry, and cell-to-cell spread, none of which are hemagglutinin, neuraminidase, or the specific F and G proteins mentioned. *Epstein-Barr virus* - **Epstein-Barr virus (EBV)** is another **herpesvirus**, possessing multiple envelope glycoproteins (e.g., gp350/220, gp42, gH, gL) that facilitate its specific entry mechanisms into B lymphocytes and epithelial cells. - Like other herpesviruses, EBV **lacks hemagglutinin and neuraminidase** and does not encode the F and G proteins seen in paramyxoviruses.

Q: Which of the following statements about Hepatitis C virus characteristics is correct?

Antibody to HCV may not be seen in the acute stage. ***Correct: Antibody to HCV may not be seen in the acute stage*** - It takes time for the body to produce a detectable antibody response after **HCV infection**, leading to a **"window period"** where antibodies are negative but the virus is present - During the **acute phase**, diagnosis relies on detecting **HCV RNA** (viral load) rather than antibodies - **Anti-HCV antibodies** typically appear **6-12 weeks** after infection, making early serological diagnosis unreliable *Incorrect: Easy to culture in standard laboratory conditions* - **HCV** is notoriously **difficult to culture** in vitro, which has historically hindered research and drug development - Its **complex viral replication cycle** and **host-specific factors** make standard laboratory culture challenging - This difficulty delayed HCV research until molecular techniques became available *Incorrect: Spreads primarily through respiratory droplets* - **HCV** is primarily transmitted through **blood-to-blood contact**, such as sharing needles, contaminated medical equipment, or blood transfusions - It does not spread through casual contact, food, water, or **respiratory droplets** - Main routes include **intravenous drug use**, **unsafe medical practices**, and historically **blood transfusions** (before screening) *Incorrect: Rarely causes chronic hepatitis* - A high percentage of individuals infected with **HCV (50-85%)** develop **chronic hepatitis**, which can lead to severe liver disease like **cirrhosis** and **hepatocellular carcinoma** - This high chronicity rate makes HCV a significant public health concern - Unlike Hepatitis A and E, HCV has a **strong tendency toward chronicity**

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: Risk of HIV transmission is not seen with

Plasma derived hepatitis B vaccine. The original text with [1] citations added (ONLY for relevant references) - **Plasma-derived hepatitis B vaccines** undergo extensive purification and inactivation processes, which effectively eliminate the risk of **HIV transmission** [1]. - The manufacturing process ensures that any potential viral contaminants, including HIV, are **inactivated** or removed, making the vaccine safe [1]. *Whole blood* - **Whole blood** transfusions carry a significant risk of **HIV transmission** if the donor is infected and the blood is not properly screened [2]. - HIV can survive in whole blood, making it a direct conduit for transmission from an infected donor to a recipient [1], [2]. *Platelets* - **Platelets** are derived from whole blood and can contain viable **HIV particles**, posing a risk of transmission during transfusion [2]. - Although the risk might be slightly lower than with whole blood due to processing, it is still a recognized route for HIV transmission [1]. *Leukocytes vaccines* - The term "leukocytes vaccines" is vague, but if it refers to products containing **leukocytes** (white blood cells), these cells are a primary host for **HIV**. - Components directly derived from or containing viable leukocytes from an infected individual would carry a high risk of HIV transmission.

Q: Causative organism of tropical spastic paraparesis is?

HTLV. ***HTLV*** - **Human T-lymphotropic virus type 1 (HTLV-1)** is the definitive causative agent for **tropical spastic paraparesis (TSP)**, also known as **HTLV-1-associated myelopathy (HAM)**. - The virus primarily infects CD4+ T-cells and leads to chronic inflammation and demyelination within the spinal cord, particularly affecting the **thoracic spinothalamic tracts** and **corticospinal tracts**. *HIV 1* - **HIV-1** can cause vacuolar myelopathy, which is a different neurological complication that presents with similar symptoms to TSP but is a direct effect of HIV rather than HTLV-1 infection. - While both can cause myelopathies, **HIV-1** is not the causative agent for tropical spastic paraparesis itself; that is specifically linked to HTLV-1. *HIV 2* - **HIV-2** is less common than HIV-1 and primarily found in West Africa. It can also cause neurological complications, but it is not directly associated with **tropical spastic paraparesis**. - Its neurological manifestations are generally milder and less frequent compared to **HIV-1**, and not classically linked to TSP. *HBV* - **Hepatitis B virus (HBV)** is a hepadnavirus primarily affecting the liver, causing hepatitis, cirrhosis, and hepatocellular carcinoma. - **HBV** is not known to directly cause neurological conditions like tropical spastic paraparesis; its extrahepatic manifestations are typically vasculitis or neuromuscular syndromes, not myelopathy.

Q: What is the causative agent of Adult T-cell Leukemia/Lymphoma (ATLL)?

HTLV-1 (Human T-lymphotropic virus type 1). ***HTLV-1 (Human T-lymphotropic virus type 1)*** - **HTLV-1** is definitively linked to the pathogenesis of **Adult T-cell Leukemia/Lymphoma (ATLL)**, a rare but aggressive form of T-cell malignancy. - The virus **immortalizes** and **transforms CD4+ T-cells**, leading to uncontrolled proliferation and the development of leukemia/lymphoma. *HIV* - **HIV** primarily causes **Acquired Immunodeficiency Syndrome (AIDS)** by targeting CD4+ T-cells, leading to their destruction and systemic immune dysfunction. - While HIV-infected individuals have an increased risk of certain lymphomas, these are typically **B-cell lymphomas** (e.g., diffuse large B-cell lymphoma, primary central nervous system lymphoma) and are linked to immune suppression, not directly caused by HIV transforming T-cells into ATLL. *EBV (Epstein-Barr Virus)* - **EBV** is associated with various **lymphoproliferative disorders** and cancers, often of B-cell origin, such as **Burkitt lymphoma**, Hodgkin lymphoma, and nasopharyngeal carcinoma. - While it infects B-cells and can cause transformation, it is not the causative agent for primary T-cell leukemias like ATLL. *HTLV-2 (Human T-lymphotropic virus type 2)* - **HTLV-2** is related to HTLV-1 but is generally **not associated with malignancy**. - It is implicated in some neurological disorders but has not been shown to cause ATLL or any other T-cell leukemia/lymphoma.

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: Poliomyelitis is diagnosed by:

Isolation of virus from stool. ***Isolation of virus from stool*** - Viral culture from **stool samples** is the most reliable method for diagnosing poliomyelitis, as the **poliovirus** is shed in feces for several weeks after infection. - This method confirms the presence of the live virus, which is crucial for distinguishing between active infection and prior exposure or vaccination. *Clinical presentation* - The clinical presentation of poliomyelitis, such as **flaccid paralysis**, can be similar to other neurological conditions, making it non-specific for definitive diagnosis. - A definitive diagnosis requires laboratory confirmation to differentiate it from other causes of **acute flaccid paralysis**, such as **Guillain-Barré syndrome**. *Antibody titer measurement in blood* - While antibody titers can indicate **exposure to poliovirus**, they do not differentiate between recent infection, past infection, or vaccination. - A significant rise in **antibody titers** between acute and convalescent phase samples might suggest recent infection, but it's not practical for rapid diagnosis. *Isolation of virus from blood* - **Poliovirus** is rarely isolated from the blood, as **viremia** is typically transient and occurs early in the infection before the onset of overt symptoms. - Detection of the virus in blood indicates an early stage of systemic spread but is less likely to be positive once neurological symptoms manifest.

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.

Question 1

Which paramyxovirus lacks hemagglutinin and neuraminidase but has fusion (F) and attachment (G) proteins?

Accepted Answer

RSV

Answer

CMV

Answer

HSV

Answer

Epstein-Barr virus

Question 2

Which of the following statements about Hepatitis C virus characteristics is correct?

Accepted Answer

Antibody to HCV may not be seen in the acute stage

Answer

Easy to culture in standard laboratory conditions

Answer

Spreads primarily through respiratory droplets

Answer

Rarely causes chronic hepatitis

Question 3

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 4

Risk of HIV transmission is not seen with

Accepted Answer

Plasma derived hepatitis B vaccine

Answer

Platelets

Answer

Leukocytes vaccines

Answer

Whole blood

Question 5

Causative organism of tropical spastic paraparesis is?

Accepted Answer

HTLV

Answer

HIV 1

Answer

HIV 2

Answer

HBV

Question 6

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 7

What is the causative agent of Adult T-cell Leukemia/Lymphoma (ATLL)?

Accepted Answer

HTLV-1 (Human T-lymphotropic virus type 1)

Answer

EBV (Epstein-Barr Virus)

Answer

HIV

Answer

HTLV-2 (Human T-lymphotropic virus type 2)

Question 8

Fifth disease is caused by which virus?

Accepted Answer

Parvovirus B19

Answer

Human Papillomavirus (HPV)

Answer

Hepatitis Virus

Answer

Cytomegalovirus (CMV)

Question 9

Poliomyelitis is diagnosed by:

Accepted Answer

Isolation of virus from stool

Answer

Clinical presentation

Answer

Antibody titer measurement in blood

Answer

Isolation of virus from blood

Question 10

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

Virology — MCQs

Virology — MCQs

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