Oncogenic Viruses Indian Medical PG Practice Questions and MCQs
Practice Indian Medical PG questions for Oncogenic Viruses. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Oncogenic Viruses Indian Medical PG Question 1: Which of the following is NOT typically associated with chronic HPV infection?
- A. Integration into host genome
- B. Increased p53 activity (Correct Answer)
- C. Expression of E6 and E7 proteins
- D. Cellular proliferation
Oncogenic Viruses Explanation: ***Increased p53 activity***
- Chronic **HPV infection**, particularly by high-risk types, leads to the expression of the viral **E6 protein**, which targets **p53 for degradation**. [3]
- Therefore, chronic HPV infection is typically associated with **decreased p53 activity**, not increased, as E6's role is to neutralize this tumor suppressor. [2]
*Integration into host genome*
- This is a hallmark of transforming infections by high-risk **HPVs**, allowing for stable expression of **viral oncogenes** like E6 and E7.
- This integration is crucial for the development of HPV-associated malignancies, as it ensures persistent expression of viral proteins that disrupt **cell cycle control**. [1]
*Expression of E6 and E7 proteins*
- **E6 and E7** are the main viral oncogenes expressed during persistent **high-risk HPV infection**.
- **E6 targets p53** for degradation, and **E7 inactivates retinoblastoma protein (pRb)**, leading to uncontrolled cell proliferation. [2]
*Cellular proliferation*
- The effects of **E6 and E7** on **p53 and pRb** remove the checks and balances on cell growth, promoting **uncontrolled cellular proliferation**. [1]
- This excessive proliferation is a key step in the development of **HPV-associated neoplasia and cancer**.
**References:**
[1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Female Genital Tract, pp. 1007-1008.
[2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, pp. 334-335.
[3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lung, pp. 739-741.
Oncogenic Viruses Indian Medical PG Question 2: Which virus is NOT associated with human cancer?
- A. HPV
- B. Measles virus (Correct Answer)
- C. HHV-8
- D. EBV
Oncogenic Viruses Explanation: ***Measles virus***
- The **measles virus** (rubeola) is primarily known for causing acute febrile illness with a characteristic rash and is not recognized as an **oncogenic virus** in humans.
- While it can cause significant morbidity and mortality, particularly in unvaccinated populations, its mode of action does not involve **cellular transformation** or sustained **oncogene expression**.
*HPV*
- **Human Papillomavirus (HPV)**, particularly high-risk types like HPV-16 and HPV-18, is a well-established cause of **cervical cancer**, as well as other anogenital and oropharyngeal cancers.
- HPV oncogenes, **E6** and **E7**, interfere with tumor suppressor proteins like p53 and Rb, promoting uncontrolled cell growth.
*HHV-8*
- **Human Herpesvirus 8 (HHV-8)**, also known as Kaposi's sarcoma-associated herpesvirus (KSHV), is the causative agent of **Kaposi's sarcoma**, a vascular tumor.
- HHV-8 is also associated with primary effusion lymphoma and multicentric Castleman's disease due to its **latency-associated nuclear antigen (LANA)** and other viral oncogenes.
*EBV*
- **Epstein-Barr Virus (EBV)** is strongly linked to several human cancers, including **Burkitt's lymphoma**, **nasopharyngeal carcinoma**, and Hodgkin's lymphoma.
- EBV transforms B lymphocytes through the expression of latency genes such as **LMP1** and **EBNA2**, which modulate cell growth and survival pathways.
Oncogenic Viruses Indian Medical PG Question 3: Asymptomatic hepatitis B is common in 2-3% of the normal population, but there is increased risk of progression to hepatocellular carcinoma. Why?
- A. Integration of viral DNA with host DNA (Correct Answer)
- B. High rate of proliferation of virus
- C. Inability to induce inflammation to remove the organism
- D. High level of transaminases
Oncogenic Viruses Explanation: ***Integration of viral DNA with host DNA***
- **Hepatitis B virus (HBV)** is a DNA virus that can integrate its DNA into the host hepatocyte genome, leading to **genomic instability** and potentially activating proto-oncogenes or disrupting tumor suppressor genes.
- This integration, along with chronic inflammation and repair, is a key mechanism driving the progression to **hepatocellular carcinoma (HCC)** even in asymptomatic carriers.
*High rate of proliferation of virus*
- While active viral replication (high viral load) is a risk factor for liver damage and HCC, the *rate of proliferation* itself isn't the primary direct cause of carcinogenesis in asymptomatic carriers.
- The direct mechanism leading to malignancy is more closely linked to how the virus interacts with the host genome rather than just its abundance.
*Inability to induce inflammation to remove the organism*
- An inability to clear the virus and a persistent **immune response** actually contribute to chronic inflammation, which is a significant factor in HCC development. However, this is not the most direct reason for the **oncogenic potential** of HBV itself.
- While a robust immune response can cause liver damage, the *lack* of one doesn't directly explain the carcinogenic potential; rather, it leads to persistence and chronic disease.
*High level of transaminases*
- **Elevated transaminase levels** (like ALT and AST) are indicators of hepatocyte damage and inflammation, not a direct cause of liver cancer.
- While chronic elevation suggests ongoing liver injury and increased risk, this is a marker of disease activity, not the fundamental mechanism of oncogenesis.
Oncogenic Viruses Indian Medical PG Question 4: Which HPV oncoprotein initiates cervical carcinogenesis primarily by inactivating the p53 tumor suppressor?
- A. E3
- B. E5
- C. E6 (Correct Answer)
- D. E7
Oncogenic Viruses Explanation: ***E6***
- **E6 oncoprotein is the HPV protein that specifically targets and degrades p53** through ubiquitin-mediated proteolysis [2].
- **p53 degradation** prevents apoptosis and allows cells with damaged DNA to survive and proliferate, a critical early step in malignant transformation [3].
- E6 works synergistically with E7 in cervical carcinogenesis, but **E6 is uniquely responsible for p53 inactivation** [1].
*E3*
- HPV does not have a clinically significant E3 oncoprotein in the context of cervical cancer pathogenesis.
- This is not a major viral oncoprotein involved in malignant transformation.
*E5*
- **E5 oncoprotein** plays a minor role in early infection by enhancing growth factor receptor signaling.
- It does **not target p53** and is often lost during viral integration, making it less critical for malignant progression.
*E7*
- **E7 oncoprotein targets the retinoblastoma protein (Rb)**, not p53 [1].
- Rb inactivation releases E2F transcription factors, driving cell cycle progression [1].
- E7 and E6 work together, but **E7's specific target is Rb, not p53** [1].
**References:**
[1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, pp. 334-335.
[2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Female Genital Tract, pp. 1006-1007.
[3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, pp. 303-304.
Oncogenic Viruses Indian Medical PG Question 5: E6 and E7 genes of which virus are implicated in oncogenesis?
- A. HPV (Correct Answer)
- B. Cytomegalovirus (CMV)
- C. Epstein-Barr Virus (EBV)
- D. Human T-lymphotropic Virus type 1 (HTLV-1)
Oncogenic Viruses Explanation: ***HPV***
- The **E6** and **E7** oncoproteins of **High-Risk Human Papillomavirus (HPV)** are critical for oncogenesis, primarily in cervical cancer.
- **E6** degrades the tumor suppressor protein **p53**, and **E7** inactivates the **retinoblastoma (Rb)** protein, leading to uncontrolled cell proliferation.
*Cytomegalovirus (CMV)*
- While CMV can be associated with certain cancers like glioblastoma, its direct role in oncogenesis does not involve specific E6/E7 genes.
- CMV primarily causes opportunistic infections and congenital abnormalities, not through the mechanism of E6/E7.
*Epstein-Barr Virus (EBV)*
- EBV is associated with various cancers such as **nasopharyngeal carcinoma** and **Burkitt lymphoma**.
- Its oncogenic mechanisms involve proteins like **LMP1** and **EBNA2**, which dysregulate cell growth, rather than E6/E7.
*Human T-lymphotropic Virus type 1 (HTLV-1)*
- HTLV-1 is the causative agent of **Adult T-cell Leukemia/Lymphoma (ATLL)**.
- Its oncogenic potential is linked to the **Tax protein**, which alters gene expression and promotes T-cell proliferation, not through E6/E7.
Oncogenic Viruses Indian Medical PG Question 6: Which of the following HPV types is MOST strongly associated with cervical cancer?
- A. HPV 18
- B. HPV 6
- C. HPV 16 (Correct Answer)
- D. HPV 11
Oncogenic Viruses Explanation: ***HPV 16***
- **HPV 16** is the most prevalent **high-risk HPV type**, accounting for approximately 50-60% of all cervical cancer cases globally.
- It's highly effective at integrating its DNA into host cells and producing **oncoproteins E6 and E7**, which promote cell proliferation and inhibit tumor suppressor genes [1].
*HPV 18*
- While **HPV 18** is also a **high-risk type** and the second most common cause of cervical cancer (around 10-15%), it is less frequently associated than HPV 16 [1].
- HPV 18 is more commonly linked to **adenocarcinomas** of the cervix, whereas HPV 16 is more often associated with **squamous cell carcinomas**.
*HPV 6*
- **HPV 6** is considered a **low-risk HPV type**, primarily associated with benign conditions such as **genital warts (condyloma acuminata)** [1].
- It rarely causes cervical cancer and is not considered an oncogenic type.
*HPV 11*
- Similar to HPV 6, **HPV 11** is also a **low-risk HPV type** and is a common cause of **genital warts**.
- It is not associated with an increased risk of cervical cancer.
**References:**
[1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, pp. 334-335.
Oncogenic Viruses Indian Medical PG Question 7: Which of the following is an RNA oncogenic virus?
- A. Cytomegalovirus (CMV)
- B. Hepatitis B Virus (HBV)
- C. Human T-lymphotropic Virus (HTLV) (Correct Answer)
- D. Human Immunodeficiency Virus (HIV)
Oncogenic Viruses Explanation: ***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.
Oncogenic Viruses Indian Medical PG Question 8: The image below shows the life cycle of a virus. Which of the proteins of the virus act as oncogenes?
- A. L1, L2
- B. E1, E2, E5
- C. E1, E2
- D. E6, E7 (Correct Answer)
Oncogenic Viruses Explanation: ***E6, E7***
- The **E6** and **E7** proteins of high-risk human papillomaviruses (HPVs) are considered **oncogenes** because they interfere with critical tumor suppressor pathways [1][2].
- **E6** promotes the degradation of **p53**, a tumor suppressor protein, while **E7** inactivates **retinoblastoma protein (pRb)**, leading to uncontrolled cell proliferation and increased risk of malignant transformation [2].
*L1, L2*
- **L1** and **L2** are **late proteins** (structural proteins) that form the **viral capsid** (outer shell) of the HPV virion.
- They are essential for assembling new viral particles but do not directly contribute to the oncogenic process by disrupting host cell cycle regulation.
*E1, E2, E5*
- **E1** is involved in **viral DNA replication**, acting as a helicase and ATPase.
- **E2** regulates **viral gene expression** and DNA replication, while **E5** is a small transmembrane protein that can contribute to cell growth but is generally considered less potent in oncogenesis than E6 and E7, and its exact role varies by HPV type.
*E1, E2*
- **E1** is critical for **viral DNA replication**, and **E2** regulates viral gene transcription and DNA replication.
- While important for the viral life cycle, neither E1 nor E2 are the primary drivers of oncogenesis in the way E6 and E7 are, as they do not directly target key tumor suppressor proteins like p53 and pRb.
**References:**
[1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Female Genital Tract, pp. 1007-1008.
[2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, pp. 334-335.
Oncogenic Viruses Indian Medical PG Question 9: All of the following are RNA viruses except
- A. Influenza virus
- B. Parainfluenza virus
- C. Mumps virus
- D. Herpes virus (Correct Answer)
Oncogenic Viruses Explanation: ***Herpes virus***
- **Herpesviruses** are a large family of **DNA viruses** that cause diseases in animals, including humans.
- They are characterized by their ability to establish **latent infections** and periodically reactivate.
*Influenza virus*
- The **influenza virus** is an **RNA virus** belonging to the family **Orthomyxoviridae**.
- It is known for causing the seasonal **flu** and respiratory infections.
*Parainfluenza virus*
- **Parainfluenza viruses** are a group of **RNA viruses** in the family **Paramyxoviridae**.
- They are a common cause of **respiratory tract infections**, especially in children, leading to conditions like **croup**.
*Mumps virus*
- The **mumps virus** is an **RNA virus** that is part of the **Paramyxoviridae** family.
- It is well-known for causing **mumps**, which is characterized by the swelling of the **parotid glands**.
Oncogenic Viruses Indian Medical PG Question 10: SARS is caused by novel variant of?
- A. Coronavirus (Correct Answer)
- B. Toga virus
- C. Lyssa virus
- D. Pox virus
Oncogenic Viruses Explanation: ***Coronavirus***
- **Severe Acute Respiratory Syndrome (SARS)** is caused by a novel strain of **coronavirus**, specifically SARS-CoV.
- Coronaviruses are a large family of viruses known to cause respiratory illnesses ranging from the common cold to more severe diseases.
*Togavirus*
- Togaviruses are a family of **RNA viruses** that include **Rubella virus** and **Alphaviruses** (e.g., Eastern equine encephalitis virus).
- They are typically transmitted by **arthropod vectors** and do not cause SARS.
*Lyssavirus*
- Lyssaviruses belong to the family Rhabdoviridae and are the causative agents of **rabies**, a severe neurological disease.
- They are transmitted through the bite of an infected animal and are not associated with SARS.
*Poxvirus*
- Poxviruses are a family of **DNA viruses** that include **Variola virus** (smallpox) and **Monkeypox virus**.
- They are known for causing characteristic skin lesions and are not responsible for SARS.
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