Virology — MCQs
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DNA polymerase of HBV is encoded by which of the following ?
Which virus has a double-stranded RNA with a segmented genome?
What is the Australian antigen for hepatitis B?
Genital warts are caused by which virus?
Rubella virus belongs to which family?
Acute Hemorrhagic Conjunctivitis is primarily caused by which type of Enterovirus?
Coxsackievirus A16 is associated with which of the following conditions?
Which of the following is not a poxvirus?
Which of the following viruses is a member of the Herpesviridae family?
Viral DNA is integrated into Bacterial DNA in:
Virology Indian Medical PG Practice Questions and MCQs
Question 1331: DNA polymerase of HBV is encoded by which of the following ?
- A. S gene
- B. C gene
- C. P gene (Correct Answer)
- D. X gene
Explanation: ***P gene*** - The **P gene** (polymerase gene) of the **Hepatitis B virus (HBV)** encodes for the viral DNA polymerase. - This enzyme is crucial for HBV replication, as it functions as both a **reverse transcriptase** and a **DNA-dependent DNA polymerase**. *S gene* - The **S gene** encodes for the **surface antigens (HBsAg)** of HBV, which are involved in viral entry and are the primary targets of the host immune response. - It does not encode for the viral polymerase. *C gene* - The **C gene** encodes for the **HBV core antigen (HBcAg)**, which forms the viral nucleocapsid. - It also produces the **e antigen (HBeAg)**, which is a secreted protein indicating active viral replication. *X gene* - The **X gene** encodes for the **HBV X protein (HBxAg)**, which is a regulatory protein involved in viral transcription and replication. - It plays a role in **hepatocarcinogenesis** but does not encode the polymerase enzyme.
Question 1332: Which virus has a double-stranded RNA with a segmented genome?
- A. Influenza
- B. Arenavirus
- C. Bunyavirus
- D. Rotavirus (Correct Answer)
Explanation: ***Rotavirus*** - Rotavirus possesses a **double-stranded RNA (dsRNA) genome** that is **segmented** into **11 segments**. - This unique genomic structure is characteristic of the *Reoviridae* family, to which Rotavirus belongs. *Influenza* - Influenza virus has a **segmented single-stranded RNA (ssRNA) genome** of negative sense, not double-stranded RNA. - It belongs to the *Orthomyxoviridae* family. *Arenavirus* - Arenaviruses have a **segmented single-stranded RNA (ssRNA) genome** with an **ambisense** polarity, not double-stranded. - Their genome typically consists of two segments. *Bunyavirus* - Bunyaviruses contain a **segmented single-stranded RNA (ssRNA) genome** of negative or ambisense polarity, not double-stranded. - Their genome is typically divided into three segments.
Question 1333: What is the Australian antigen for hepatitis B?
- A. HBsAg (Correct Answer)
- B. HBeAg
- C. HBDAg
- D. HBV DNA
Explanation: ***HBsAg*** - **HBsAg** stands for **Hepatitis B surface antigen**, which was originally discovered by Baruch Blumberg in 1965 and was initially called the **Australia antigen** due to its discovery in the serum of an Australian aboriginal. - Its presence indicates an **active hepatitis B infection**, either acute or chronic. *HBeAg* - **HBeAg** (Hepatitis B e-antigen) is a marker of **viral replication** and **infectivity**. - It is distinct from HBsAg and indicates a high level of **transmissibility** of the virus. *HBDAg* - **HBDAg** is not a standard or recognized antigen for hepatitis B. - The correct antigen for hepatitis D is **HDAg** (Hepatitis D antigen), which is only found in individuals co-infected with hepatitis D virus and hepatitis B virus. *HBV DNA* - **HBV DNA** refers to the viral genetic material of the hepatitis B virus. - While its presence indicates active viral replication and is used to monitor **viral load**, it is not an antigen but rather the **viral genome** itself.
Question 1334: Genital warts are caused by which virus?
- A. Cytomegalovirus (CMV)
- B. Herpes simplex virus (HSV)
- C. Human Papillomavirus (HPV) (Correct Answer)
- D. Varicella zoster virus (VZV)
Explanation: ***Human Papillomavirus (HPV)*** - **HPV** is the causative agent of **genital warts**, which are benign epithelial growths. - Specific low-risk HPV types, primarily **HPV types 6 and 11**, are responsible for the vast majority of genital wart cases. *Herpes simplex virus (HSV)* - **HSV** causes **genital herpes**, characterized by painful blisters and ulcers, not warts. - There are two main types: **HSV-1** (often oral herpes) and **HSV-2** (primarily genital herpes). *Cytomegalovirus (CMV)* - **CMV** is a common virus that usually causes **asymptomatic infection** in healthy individuals but can lead to severe disease in immunocompromised patients or neonates. - It is not associated with the formation of genital warts. *Varicella zoster virus (VZV)* - **VZV** is responsible for **chickenpox** (varicella) in primary infection and **shingles** (herpes zoster) during reactivation. - It does not cause genital warts.
Question 1335: Rubella virus belongs to which family?
- A. Orthomyxovirus
- B. Rheovirus
- C. Togavirus (Correct Answer)
- D. Picornavirus
Explanation: ***Togavirus*** - The **Rubella virus** is categorized under the family **Togaviridae**, specifically within the genus *Rubivirus*. - This classification is based on its genetic structure, being an **enveloped, positive-sense, single-stranded RNA virus**. *Rheovirus* - **Reoviruses** are characterized by a **double-stranded segmented RNA genome** and are typically non-enveloped. - This contrasts with Rubella's single-stranded, non-segmented RNA and enveloped structure. *Picornavirus* - **Picornaviruses** are a family of **non-enveloped, positive-sense, single-stranded RNA viruses** that are structurally different from Rubella. - Examples include species like **poliovirus** and **rhinovirus**, which do not share the distinct biological properties of Rubella. *Orthomyxovirus* - **Orthomyxoviruses** are a family of **enveloped, negative-sense, segmented RNA viruses**, which includes influenza viruses. - Their genomic organization and replication strategy are fundamentally different from those of the Rubella virus.
Question 1336: Acute Hemorrhagic Conjunctivitis is primarily caused by which type of Enterovirus?
- A. Enterovirus type 68
- B. Enterovirus type 69
- C. Enterovirus type 70 (Correct Answer)
- D. Enterovirus type 71
Explanation: ***Enterovirus type 70*** - **Enterovirus type 70** is the most common cause of **Acute Hemorrhagic Conjunctivitis (AHC)**, particularly in epidemic outbreaks. - AHC presents with rapid onset of **ocular pain**, **redness**, **swelling**, and **subconjunctival hemorrhages**. *Enterovirus type 68* - **Enterovirus D68 (EV-D68)** is primarily known for causing **respiratory illnesses**, ranging from mild to severe, and is associated with acute flaccid myelitis. - While it can cause respiratory symptoms, it is not a primary cause of **Acute Hemorrhagic Conjunctivitis**. *Enterovirus type 69* - **Enterovirus type 69** is a rare serotype and is not typically associated with specific human diseases or large-scale outbreaks. - Unlike EV70, it is not recognized as a significant cause of **conjunctivitis**. *Enterovirus type 71* - **Enterovirus A71 (EV-A71)** is a common cause of **hand, foot, and mouth disease (HFMD)**, especially in children, and can also lead to severe neurological complications. - While it causes various infections, it is not the primary cause of **hemorrhagic conjunctivitis**.
Question 1337: Coxsackievirus A16 is associated with which of the following conditions?
- A. Herpangina
- B. Hand-foot-mouth disease (Correct Answer)
- C. Yellow fever
- D. Myocarditis
Explanation: ***Hand-foot-mouth disease*** - **Coxsackievirus A16** is one of the most common causative agents of **hand-foot-mouth disease**, characterized by fever, oral ulcers, and a rash on the hands and feet. - This viral infection is highly contagious and frequently seen in young children. *Herpangina* - While also caused by **Coxsackieviruses** (primarily **Coxsackievirus A** types like A10 or A2), **herpangina** typically presents with lesions restricted to the posterior oropharynx, without the characteristic hand and foot rash seen in HFMD. - It involves sudden onset of fever, sore throat, and small vesicles or ulcers on the **soft palate, tonsillar pillars, and uvula**. *Yellow fever* - **Yellow fever** is caused by the **yellow fever virus**, a flavivirus, and is transmitted by mosquitoes. - It presents with fever, jaundice, and hemorrhagic symptoms, completely distinct from enteroviral infections. *Myocarditis* - **Myocarditis** can be caused by various viruses, including other **enteroviruses** like **Coxsackievirus B** types (e.g., B1-B5), along with adenoviruses and parvovirus B19. - However, **Coxsackievirus A16** is not a primary cause of myocarditis; its association is predominantly with hand-foot-mouth disease.
Question 1338: Which of the following is not a poxvirus?
- A. Molluscum contagiosum
- B. Orf virus
- C. Vaccinia virus
- D. Coxsackie virus (Correct Answer)
Explanation: ***Coxsackie virus*** - The **Coxsackie virus** belongs to the family **Picornaviridae**, not Poxviridae. - It is known for causing diseases such as **hand, foot, and mouth disease**, herpangina, and myocarditis. *Vaccinia virus* - **Vaccinia virus** is a well-known member of the **Poxviridae** family, historically used in the smallpox vaccine. - It is a **large, complex DNA virus** that replicates in the cytoplasm of infected cells. *Molluscum contagiosum* - **Molluscum contagiosum virus (MCV)** is a **poxvirus** that causes a mild skin infection characterized by raised, pearly, umbilicated lesions. - It primarily infects **humans**, causing localized lesions that are spread through direct contact. *Orf virus* - **Orf virus**, also known as contagious pustular dermatitis virus, is a **poxvirus** that primarily affects sheep and goats. - It can be transmitted to humans, causing single papular or nodular lesions, usually on the fingers, hands, or forearms.
Question 1339: Which of the following viruses is a member of the Herpesviridae family?
- A. Variola
- B. Adenovirus
- C. HPV
- D. Herpes Simplex Virus (Correct Answer)
Explanation: ***Herpes Simplex Virus*** - **Herpes Simplex Virus (HSV)** is the type species of the *Herpesviridae* family, which includes other common human pathogens such as **cytomegalovirus** and **Epstein-Barr virus**. - Members of this family are characterized by a **double-stranded DNA genome**, an icosahedral capsid, and an envelope, and they typically cause **latent infections**. *Variola* - **Variola virus** is a member of the *Poxviridae* family, known for causing **smallpox**, a historically devastating disease. - Unlike herpesviruses, poxviruses are **large and complex DNA viruses** that replicate entirely in the cytoplasm of infected cells. *Adenovirus* - **Adenovirus** belongs to the *Adenoviridae* family and is a **non-enveloped DNA virus** known for causing a variety of conditions, including respiratory infections and conjunctivitis. - Its structure and replication cycle differ significantly from the enveloped *Herpesviridae*. *HPV* - **HPV (Human Papillomavirus)** is a member of the *Papillomaviridae* family, which are small **non-enveloped DNA viruses** associated with warts and certain cancers. - It is distinct from herpesviruses in its genomic organization, capsid structure, and disease manifestations.
Question 1340: Viral DNA is integrated into Bacterial DNA in:
- A. Lysogenic cycle (Correct Answer)
- B. Bacterial transduction
- C. Bacterial transformation
- D. Bacterial conjugation
Explanation: ***Lysogenic cycle*** - In the **lysogenic cycle**, the **bacteriophage DNA integrates** into the host bacterial chromosome, becoming a **prophage**. - This integration allows the viral genome to be **replicated along with the host DNA** without immediately lysing the cell. *Bacterial transduction* - **Transduction** involves the transfer of **bacterial DNA** from one bacterium to another via a bacteriophage, not the integration of viral DNA into the host genome. - While phages are involved, the primary event is the accidental packaging and transfer of bacterial genes, not viral integration into the host for replication. *Bacterial transformation* - **Transformation** is the process where bacteria take up **naked DNA from their environment** and incorporate it into their own genome. - This DNA is typically from another bacterium or is artificially introduced, not viral DNA undergoing a natural integration process within the cell. *Bacterial conjugation* - **Conjugation** is the transfer of genetic material (usually a **plasmid**) between bacteria through direct cell-to-cell contact, mediated by a **pilus**. - This process involves the transfer of bacterial or plasmid DNA, not the integration of a viral genome into the host chromosome.
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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