Virology Practice Questions

Q: Which of the following viruses is considered a defective virus that requires another virus for its replication?

Hepatitis D virus (HDV). ***Hepatitis D virus (HDV)*** - **Hepatitis D virus (HDV)** is a unique RNA virus that is **defective** and requires the presence of **Hepatitis B virus (HBV)** and its surface antigen **(HBsAg)** for replication and assembly. - HDV infection can occur as **co-infection** (simultaneous HBV and HDV) or **superinfection** (HDV infection in an existing HBV carrier), often leading to **more severe liver disease**. - HDV is a **satellite virus** that cannot complete its life cycle independently. *Incorrect: Hepatitis A virus (HAV)* - **Hepatitis A virus (HAV)** is a **picornavirus** that causes acute hepatitis and **replicates independently** without the need for another helper virus. - It is transmitted via the **fecal-oral route** and does **not cause chronic infection**. *Incorrect: Hepatitis B virus (HBV)* - **Hepatitis B virus (HBV)** is a **hepadnavirus** that **replicates independently** and produces its own viral envelopes. - HBV is the **helper virus required for HDV replication**, but HBV itself does not require another virus to complete its life cycle. *Incorrect: Hepatitis C virus (HCV)* - **Hepatitis C virus (HCV)** is a **flavivirus** that can **replicate autonomously** and cause both acute and chronic hepatitis. - It does **not require a helper virus** for its replication, unlike HDV.

Q: Herpes zoster ophthalmicus is caused by:

VZV. ***Correct Answer: VZV*** - **Varicella-zoster virus (VZV)** is the causative agent of **herpes zoster ophthalmicus**, which is a reactivation of the virus in the ophthalmic division of the trigeminal nerve. - The initial infection with VZV causes **chickenpox (varicella)**, and the virus remains dormant in sensory ganglia to reactivate later as shingles. *Incorrect - HPV* - **Human papillomavirus (HPV)** is primarily known for causing **warts** and is a significant risk factor for certain **cancers**, particularly cervical cancer. - HPV does not cause vesicular rashes associated with herpes zoster or ophthalmic involvement. *Incorrect - HSV* - **Herpes simplex virus (HSV)** causes different forms of herpes infections, such as **oral (cold sores)** and **genital herpes**, and can also cause keratitis but is distinct from zoster ophthalmicus. - While HSV can affect the eye, leading to **herpes simplex keratitis**, it produces a different clinical picture and does not involve the dermatomal rash characteristic of zoster. *Incorrect - CMV* - **Cytomegalovirus (CMV)** is a common virus often causing asymptomatic infections in healthy individuals. - In immunocompromised patients, CMV can cause serious diseases, including **retinitis**, but it does not cause herpes zoster ophthalmicus.

Q: Which pox virus does Variola belong to?

Orthopoxvirus. ***Orthopoxvirus*** - **Variola virus**, the causative agent of **smallpox**, is a member of the **Orthopoxvirus genus**. - Other notable members of this genus include **vaccinia virus** (used in smallpox vaccine) and **monkeypox virus**. *Parapoxvirus* - This genus includes viruses such as **Orf virus**, which causes contagious pustular dermatitis in sheep and goats, occasionally transmitted to humans. - Parapoxviruses typically cause localized skin lesions and are not associated with **smallpox**. *Yatapox virus* - The **Yatapox virus genus** includes the **Tanapox virus** and **Yabapox virus**, which primarily affect monkeys but can cause mild, self-limiting skin lesions in humans. - They are distinct from the **Variola virus** and do not cause smallpox. *Molluscipox virus* - This genus contains **Molluscum contagiosum virus**, which causes **molluscum contagiosum**, a common skin infection characterized by small, flesh-colored, dome-shaped papules. - It is genetically and clinically distinct from **Variola virus**.

Q: Which virus is implicated in Burkitt's lymphoma?

Epstein-Barr virus. ***Epstein-Barr virus*** - The **Epstein-Barr virus (EBV)** is strongly associated with Burkitt's lymphoma, particularly the endemic form found in equatorial Africa. - EBV infection leads to **B-cell proliferation** and can promote oncogenesis in the presence of other co-factors, such as a c-MYC translocation. *Arbovirus* - **Arboviruses** are transmitted by arthropod vectors (e.g., mosquitoes, ticks) and cause diseases like dengue fever and Zika virus, not Burkitt's lymphoma. - They primarily cause **viremia** and symptoms related to central nervous system involvement or hemorrhagic fever. *Picornavirus* - **Picornaviruses** are a family of small, non-enveloped RNA viruses that include enteroviruses (e.g., poliovirus, coxsackievirus) and rhinoviruses. - They typically cause diseases like **poliomyelitis**, **common cold**, and **gastroenteritis**, not lymphoid malignancies. *Coxsackievirus* - **Coxsackieviruses** are a genus of enteroviruses within the Picornaviridae family and are known to cause diseases such as hand-foot-and-mouth disease, myocarditis, and aseptic meningitis. - There is **no established link** between Coxsackievirus infection and Burkitt's lymphoma.

Q: All of the following are true about the papovavirus except:

They are RNA viruses.. ***They are RNA viruses*** - Papovaviruses, including **polyomaviruses** and **papillomaviruses**, are **double-stranded DNA viruses**, not RNA viruses. - Their genome is composed of **DNA**, which is a key characteristic distinguishing them from RNA viruses. *Papovaviruses can produce papillomas in humans* - **Human Papillomaviruses (HPVs)**, a subgroup of papovaviruses, are well-known for causing **papillomas** (warts) in humans. - Certain high-risk HPVs are also associated with **cervical cancer** and other anogenital cancers. *SV - 40 is oncogenic* - **Simian Virus 40 (SV40)**, a type of polyomavirus (which falls under the broader papovavirus group), is indeed **oncogenic** in certain animal models. - It has been studied extensively for its ability to induce tumors and transform cells in vitro through its **tumor antigens**. *They are non-enveloped icosahedral viruses* - Both **polyomaviruses** and **papillomaviruses** share the structural characteristic of being **non-enveloped**. - They also possess an **icosahedral capsid** symmetry, which encases their DNA genome.

Q: The EBV receptor located on the surface of B cells is?

CD21. ***CD21*** - CD21 acts as a receptor for **Epstein-Barr Virus (EBV)** on the surface of B cells, facilitating viral entry [1][2]. - It also plays a role in B cell activation and **signal transduction** upon antigen binding [1]. *CD22* - CD22 is a **negative regulatory** molecule that contributes to B cell function but does not serve as a receptor for EBV. - It primarily modulates the response to **B cell receptor (BCR)** signaling. *CD24* - CD24 is a **glycoprotein** involved in cell adhesion and does not act as a receptor for EBV on B cells. - It is not prominently associated with the functions related to viral entry or B cell activation. *CD23* - CD23 is a low-affinity IgE receptor involved in regulating **B cell activation**, but it is not the receptor for EBV. - Its main roles relate to **allergic responses** and not viral interactions. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of the Immune System, pp. 199-200. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Infectious Diseases, pp. 368-369.

Q: Which of the following is an RNA oncogenic virus?

Human T-lymphotropic Virus (HTLV). ***Human T-lymphotropic Virus (HTLV)*** - **HTLV-1** is a well-established **RNA oncogenic virus** that causes Adult T-cell Leukemia/Lymphoma (ATLL). - It utilizes **reverse transcriptase** to convert its RNA genome into DNA, which then integrates into the host cell's genome, leading to malignant transformation. *Cytomegalovirus (CMV)* - CMV is a **DNA virus** and belongs to the Herpesviridae family. - While it can cause disease, it is not primarily classified as an **oncogenic virus**, although some studies suggest associations with certain cancers. *Hepatitis B Virus (HBV)* - HBV is a **DNA virus** that primarily causes acute and chronic hepatitis. - It is a major risk factor for **hepatocellular carcinoma (HCC)**, but it itself is a DNA virus, not an RNA virus. *Human Immunodeficiency Virus (HIV)* - HIV is an **RNA retrovirus**, but it is generally considered **non-oncogenic** in the direct sense. - While HIV-infected individuals have an increased risk of certain cancers (e.g., Kaposi's sarcoma, non-Hodgkin lymphoma), these are usually due to **immunosuppression** allowing co-infecting oncogenic viruses (like HHV-8 or EBV) to proliferate, rather than direct oncogenic action of HIV itself.

Q: Which virus characteristically reactivates in a dermatomal distribution?

Herpes zoster. ***Herpes zoster (Correct Answer)*** - This virus, also known as **varicella-zoster virus (VZV)**, causes **chickenpox** during primary infection and remains latent in **sensory ganglia** (dorsal root ganglia). - Upon reactivation, it travels along the **sensory nerve** to the skin, producing a characteristic **vesicular rash in a dermatomal distribution**. - This dermatomal pattern is the hallmark clinical feature that distinguishes zoster reactivation. *Herpes simplex (Incorrect)* - **Herpes simplex virus (HSV)** typically causes **localized outbreaks** like cold sores (HSV-1) or genital herpes (HSV-2). - While it establishes latency in sensory ganglia, its reactivation pattern usually involves a **smaller, localized area** rather than a full dermatome. - Reactivation occurs at the same site repeatedly, not in a dermatomal distribution. *Influenza virus (Incorrect)* - This is a **respiratory virus** that causes acute systemic symptoms like fever, cough, and myalgia. - It does **not establish latency** in ganglia or any other tissue. - It causes no skin manifestations or dermatomal rashes; it primarily affects the **respiratory tract**. *Rotavirus (Incorrect)* - Rotavirus is a common cause of **gastroenteritis**, particularly in infants and young children. - It replicates in the **gastrointestinal tract** and causes severe diarrhea and vomiting. - It does **not establish latency** and has no skin manifestations or dermatomal distribution.

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

Cultivated in cell culture. ***Cultivated in cell culture*** - **Norwalk virus** (now known as **norovirus**) is notoriously difficult to cultivate in standard laboratory cell cultures, making research and vaccine development challenging. - Its inability to grow in vitro is a defining characteristic, differentiating it from many other common viruses. *Belongs to calciviridae* - This statement is **true**; Norwalk virus is the prototype and best-known member of the genus *Norovirus* within the family **Caliciviridae**. - **Caliciviridae** are a family of non-enveloped, positive-sense, single-stranded RNA viruses. *Causes gastroenteritis* - This statement is **true**; Norovirus is the leading cause of **acute gastroenteritis** worldwide, particularly in outbreaks in crowded settings such as cruise ships, hospitals, and schools. - It causes symptoms like **nausea, vomiting, diarrhea**, and abdominal cramps. *Is a RNA virus* - This statement is **true**; Norovirus has a **single-stranded, positive-sense RNA genome**. - Its RNA genome is essential for its replication cycle as it can directly serve as mRNA.

Question 1

Which of the following viruses is considered a defective virus that requires another virus for its replication?

Accepted Answer

Hepatitis D virus (HDV)

Answer

Hepatitis A virus (HAV)

Answer

Hepatitis B virus (HBV)

Answer

Hepatitis C virus (HCV)

Question 2

Dengue hemorrhagic fever is primarily associated with which type of infection?

Accepted Answer

Secondary infection with a different serotype of the dengue virus

Answer

Infection with the same dengue virus repeatedly

Answer

Infection with dengue virus in an immunocompromised host

Answer

Infection with multiple serotypes of the dengue virus

Question 3

Herpes zoster ophthalmicus is caused by:

Accepted Answer

VZV

Answer

HPV

Answer

HSV

Answer

CMV

Question 4

Which pox virus does Variola belong to?

Accepted Answer

Orthopoxvirus

Answer

Parapoxvirus

Answer

Yatapox virus

Answer

Molluscipox virus

Question 5

Which virus is implicated in Burkitt's lymphoma?

Accepted Answer

Epstein-Barr virus

Answer

Arbovirus

Answer

Picornavirus

Answer

Coxsackievirus

Question 6

All of the following are true about the papovavirus except:

Accepted Answer

They are RNA viruses.

Answer

Papovaviruses can produce papillomas in humans.

Answer

SV - 40 is oncogenic

Answer

They are non-enveloped icosahedral viruses

Question 7

The EBV receptor located on the surface of B cells is?

Accepted Answer

CD21

Answer

CD23

Answer

CD24

Answer

CD22

Question 8

Which of the following is an RNA oncogenic virus?

Accepted Answer

Human T-lymphotropic Virus (HTLV)

Answer

Cytomegalovirus (CMV)

Answer

Hepatitis B Virus (HBV)

Answer

Human Immunodeficiency Virus (HIV)

Question 9

Which virus characteristically reactivates in a dermatomal distribution?

Accepted Answer

Herpes zoster

Answer

Herpes simplex

Answer

Rotavirus

Answer

Influenza virus

Question 10

Which of the following statements about Norwalk virus is false?

Accepted Answer

Cultivated in cell culture

Answer

Is a RNA virus

Answer

Causes gastroenteritis

Answer

Belongs to Caliciviridae

Virology — MCQs

Virology — MCQs

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