Virology Practice Questions

Q: How many segments of RNA does the Influenza virus have?

8 segments of single-stranded RNA. ***8 segments of single-stranded RNA*** - The **Influenza virus** is characterized by its segmented genome, which consists of **eight distinct negative-sense single-stranded RNA (ssRNA)** molecules. - This segmentation is crucial for its high mutation rate and ability to undergo **antigenic shift** and **antigenic drift**, leading to new strains. *5 segments of single-stranded RNA* - This option is incorrect because the Influenza virus specifically has **eight segments**, not five. - While it is a single-stranded RNA virus, the number of segments is a key characteristic. *8 segments of double-stranded DNA* - This option is incorrect as Influenza is an **RNA virus**, not a DNA virus, and its genetic material is single-stranded, not double-stranded. - No known influenza viruses have a **double-stranded DNA genome**. *8 segments of single-stranded DNA* - This option is incorrect because Influenza is an **RNA virus**, not a DNA virus. - Its genetic material is composed of **RNA**, specifically negative-sense single-stranded RNA.

Q: Which of the following is true about Hepatitis A virus?

Common cause of hepatitis in children. ***Common cause of hepatitis in children*** - **Hepatitis A virus (HAV)** infection is often acquired in childhood, particularly in areas with poor sanitation, and many infections are **asymptomatic** or mild in children [1]. - Due to their developing immune systems and often exposure in daycare or school settings, children are a highly susceptible population for HAV transmission [1]. *Causes cirrhosis* - **HAV infection** is an **acute self-limiting illness** and typically does not lead to chronic liver disease or cirrhosis [1]. - **Cirrhosis** is primarily associated with chronic viral hepatitis (e.g., HBV, HCV), alcohol-related liver disease, or certain autoimmune conditions. *Helps HDV replication* - **Hepatitis D virus (HDV)** is a **defective virus** that requires the presence of **Hepatitis B virus (HBV)** surface antigen (HBsAg) for its replication and assembly [1]. - **HAV** has no role in the replication or pathogenesis of **HDV** [1]. *Causes chronic hepatitis* - **HAV infection** results in an **acute inflammatory response** in the liver that resolves spontaneously in most cases [1]. - Unlike **HBV** and **HCV**, **HAV** does not establish a persistent infection and, therefore, does not cause chronic hepatitis [1].

Q: Macrophage tropic strains of HIV use which co-receptor?

CCR5. ***CCR5*** - **Macrophage-tropic** HIV strains, also known as **R5 strains**, primarily use the **CCR5 co-receptor** to enter target cells. - These strains are typically involved in the **initial infection** and transmission of HIV. - CCR5-tropic viruses are usually the **predominant strains transmitted** during sexual transmission. *CXCR4* - **T-cell-tropic** HIV strains, or **X4 strains**, preferentially utilize the **CXCR4 co-receptor** for cell entry. - These strains are associated with a **more rapid decline in CD4+ T-cell counts** during later stages of HIV infection. - Emergence of X4 strains is linked to **disease progression**. *CCR3* - While a chemokine receptor, **CCR3** is not a primary co-receptor used by common HIV strains for entry into macrophages or T cells. - CCR3 is primarily involved in **eosinophil chemotaxis** and allergic responses. *CCR2* - **CCR2** is another chemokine receptor but is **not a major co-receptor** for HIV entry. - While some laboratory-adapted strains may show minor usage, it is not clinically significant for macrophage-tropic HIV strains.

Q: Which gene of the hepatitis B virus has the longest coding sequence?

P gene. ***P gene*** - The **P gene** (polymerase gene) encodes the viral **reverse transcriptase**, which is crucial for replicating the HBV genome. - This enzyme is very large and complex, requiring the **longest coding sequence** to accommodate all its functional domains. *X gene* - The **X gene** encodes the **HBx protein**, which is a transcriptional transactivator and plays a role in hepatocarcinogenesis. - It has a relatively **short coding sequence** compared to the P gene. *S gene* - The **S gene** encodes the **surface antigens (HBsAg)**, which are involved in viral entry and immune evasion. - It has a **shorter coding sequence** than the P gene, as it primarily codes for structural proteins. *C gene* - The **C gene** encodes the **core protein (HBcAg)**, which forms the viral nucleocapsid, and the **HBeAg**. - Its coding sequence is also **shorter** than that of the P gene, reflecting its role in structural and regulatory functions.

Q: Which virus has the highest chance of transmission to the newborn during delivery?

HSV. ***HSV*** - **Herpes Simplex Virus (HSV)** has the **highest transmission rate during vaginal delivery** if the mother has active genital lesions, with transmission rates of **30-50% for recurrent infection** and up to **85-90% for primary infection**. - Neonatal herpes can lead to severe disseminated disease, central nervous system involvement, or mucocutaneous lesions with high morbidity and mortality. - **Cesarean section is indicated** if active lesions are present at the time of labor to prevent transmission. *CMV* - **Cytomegalovirus (CMV)** is primarily transmitted **congenitally (in utero)** rather than during delivery. - While perinatal transmission can occur through cervical secretions or blood during delivery, the rate is **much lower** than HSV and most postnatal transmission occurs through **breastfeeding**. - Intrapartum transmission, when it occurs, generally causes less severe disease compared to congenital infection. *VZV* - **Varicella-Zoster Virus (VZV)** transmission to the newborn occurs primarily when maternal infection develops **within 5 days before to 2 days after delivery**. - This can cause severe neonatal varicella, but the **overall intrapartum transmission rate is lower** than HSV. - Most severe fetal effects occur with **congenital varicella syndrome** (first or second trimester infection). *Rubella* - **Rubella** is almost exclusively transmitted **congenitally during early pregnancy**, leading to **congenital rubella syndrome**. - There is **no significant transmission during delivery** itself. - The critical period for fetal damage is during the first trimester, not at the time of birth.

Q: Exanthema subitum is caused by which virus?

HHV-6. ***HHV-6*** - **Human Herpesvirus 6 (HHV-6)** is the primary cause of **exanthema subitum**, also known as **roseola infantum**. - This viral infection typically affects young children and is characterized by a **high fever** followed by a **maculopapular rash** once the fever subsides. *HIV (Human Immunodeficiency Virus)* - HIV causes **acquired immunodeficiency syndrome (AIDS)**, a condition characterized by a progressive failure of the immune system. - While HIV can cause various skin manifestations, it is not responsible for **exanthema subitum**. *HCV (Hepatitis C Virus)* - HCV is the primary cause of **hepatitis C**, a liver disease that can lead to chronic liver inflammation, cirrhosis, and liver cancer. - Skin manifestations associated with HCV are generally different from exanthema subitum, such as **porphyria cutanea tarda** or **lichen planus**. *HPV (Human Papillomavirus)* - HPV is a group of viruses that cause **warts** (papillomas) and can lead to certain types of **cancers**, including cervical cancer. - It does not cause **exanthema subitum**.

Q: Bollinger bodies are seen in ?

Fowlpox. **IMPORTANT NOTE:** In **human pathology**, the term "Bollinger bodies" classically refers to **sulfur granules** seen in **actinomycosis** (Actinomyces infection), which appear as basophilic masses with radiating eosinophilic clubs. However, this question uses the **veterinary pathology** definition, where Bollinger bodies refer to viral inclusions in avian diseases. ***Fowlpox*** - In **veterinary pathology**, **Bollinger bodies** are characteristic large, eosinophilic **intracytoplasmic inclusion bodies** found in cells infected with the **fowlpox virus** (avipoxvirus). - These inclusions are visible under light microscopy and are a diagnostic feature of **fowlpox**, a widespread avian disease. - Note: Fowlpox is **not a human disease** but affects birds. *Chickenpox* - Chickenpox, caused by the **varicella-zoster virus (VZV)**, is characterized by **intranuclear inclusion bodies** (Cowdry type A) [1]. - It does not form **Bollinger bodies**. *Cowpox* - Cowpox is caused by the **cowpox virus**, an **orthopoxvirus**, and produces **A-type cytoplasmic inclusion bodies** (A-type inclusions). - While these are cytoplasmic inclusions, they are not referred to as **Bollinger bodies**. *Smallpox* - Smallpox, caused by the **variola virus** (orthopoxvirus), is associated with **Guarnieri bodies**, which are **cytoplasmic inclusion bodies**. - These inclusions are distinct from **Bollinger bodies**. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Infectious Diseases, pp. 366-367.

Q: Which of the following viruses is classified as a poxvirus?

Variola. ***Variola virus*** - **Variola virus** is the causative agent of **smallpox**, a historically significant and highly contagious disease. - It belongs to the **Orthopoxvirus** genus within the **Poxviridae family**, characterized by its large, brick-shaped virion and dsDNA genome. *Coxsackie virus* - **Coxsackieviruses** are part of the **Picornaviridae family**, specifically the **Enterovirus** genus. - They are known to cause a range of diseases including **hand-foot-and-mouth disease**, myocarditis, and aseptic meningitis, and are much smaller than poxviruses. *ECHO virus* - **Echoviruses** (Enteric Cytopathic Human Orphan viruses) are also members of the **Picornaviridae family** and the **Enterovirus** genus. - They are associated with diseases such as **aseptic meningitis**, gastroenteritis, and respiratory infections, completely distinct from poxviruses. *HSV (Herpes Simplex Virus)* - **Herpes Simplex Viruses** belong to the **Herpesviridae family**, characterized by a **linear dsDNA genome** and an enveloped icosahedral capsid. - They cause diseases like **oral and genital herpes** and are structurally and genetically distinct from poxviruses.

Q: What is the primary function of the Nef gene in HIV?

Enhancing viral pathogenesis. ***Enhancing viral pathogenesis*** - The **Nef protein** is critical for efficient viral replication and disease progression in HIV-infected individuals, significantly increasing **viral load** and contributing to immune evasion. - It achieves this by downregulating **CD4** and **MHC class I** molecules on the surface of infected cells, thereby preventing immune recognition and increasing viral infectivity. *Enhancing the expression of host genes* - While Nef interacts with various host proteins, its primary function is not to globally enhance the expression of host genes but rather to modulate specific host pathways to favor viral replication. - Instead, Nef often leads to **downregulation** of specific host proteins important for immune response, such as CD4 and MHC class I. *Decreasing viral replication* - Nef's role is to **increase**, not decrease, viral replication and spread within the host. - Viruses lacking a functional Nef gene show **attenuated replication** in vivo and often reduced pathogenicity. *Promoting host cell apoptosis* - While Nef can influence cellular processes, its direct and primary function is not to promote host cell apoptosis. - In fact, Nef can sometimes prevent early apoptosis of infected cells, allowing more time for virus production and release, thereby contributing to viral persistence.

Q: Which virus is known for its brick-shaped morphology?

Smallpox. ***Smallpox*** - The **variola virus**, responsible for smallpox, is a type of **poxvirus** which characteristically exhibits a **brick-shaped** or ovoid morphology. - This distinctive shape is due to its **large, complex virion structure** containing a dumbbell-shaped core. *Chickenpox* - Chickenpox is caused by the **varicella-zoster virus (VZV)**, which is a member of the **herpesviridae family**. - Herpesviruses are typically **spherical** with an icosahedral capsid. *CMV* - **Cytomegalovirus (CMV)** is another member of the **herpesviridae family**, sharing the characteristic **spherical shape** with an icosahedral capsid. - Its morphology is not brick-shaped. *EBV* - **Epstein-Barr virus (EBV)** is also a **herpesvirus** and thus possesses a **spherical, icosahedral capsid morphology**. - Its structure is distinct from the brick-shaped poxviruses.

Question 1

How many segments of RNA does the Influenza virus have?

Accepted Answer

8 segments of single-stranded RNA

Answer

5 segments of single-stranded RNA

Answer

8 segments of double-stranded DNA

Answer

8 segments of single-stranded DNA

Question 2

Which of the following is true about Hepatitis A virus?

Accepted Answer

Common cause of hepatitis in children

Answer

Causes chronic hepatitis

Answer

Helps HDV replication

Answer

Causes cirrhosis

Question 3

Macrophage tropic strains of HIV use which co-receptor?

Accepted Answer

CCR5

Answer

CXCR4

Answer

CCR3

Answer

CCR2

Question 4

Which gene of the hepatitis B virus has the longest coding sequence?

Accepted Answer

P gene

Answer

X gene

Answer

S gene

Answer

C gene

Question 5

Which virus has the highest chance of transmission to the newborn during delivery?

Accepted Answer

HSV

Answer

CMV

Answer

VZV

Answer

Rubella

Question 6

Exanthema subitum is caused by which virus?

Accepted Answer

HHV-6

Answer

HCV

Answer

HPV

Answer

HIV

Question 7

Bollinger bodies are seen in ?

Accepted Answer

Fowlpox

Answer

Chickenpox

Answer

Cowpox

Answer

Smallpox

Question 8

Which of the following viruses is classified as a poxvirus?

Accepted Answer

Variola

Answer

Coxsackie

Answer

ECHO

Answer

HSV

Question 9

What is the primary function of the Nef gene in HIV?

Accepted Answer

Enhancing viral pathogenesis

Answer

Enhancing the expression of host genes

Answer

Decreasing viral replication

Answer

Promoting host cell apoptosis

Question 10

Which virus is known for its brick-shaped morphology?

Accepted Answer

Smallpox

Answer

Chickenpox

Answer

CMV

Answer

EBV

Virology — MCQs

Virology — MCQs

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