Viral Infections — MCQs
LMP 1 gene plays a role in oncogenesis induced by
How many segments of RNA does the Influenza virus have?
A child presented with bluish-white spots in the mouth followed by a rash. What is the genome of the most likely causative agent?
Which of the following diseases has the largest submerged portion in the iceberg model of disease?
A child presents with a fever and a rash. Urine examination showed cells with owl's eye appearance. What is the most likely diagnosis?
The following are true about Epstein-Barr virus (EBV) except which of the following?
An elderly man who had been in several military conflicts during the early 1980s and received blood transfusions for injuries recently consulted his physician for a diagnosis of cryoglobulinemia and glomerulonephritis. Additional testing revealed that he was infected with a virus transmitted through blood. Which virus was involved in this infection?
Which of the following is an RNA oncogenic virus?
A patient presents with a viral infection that shows intranuclear inclusions in epithelial cells on biopsy. Which virus is most likely responsible?
One day after delivery, an African American female newborn develops yellow discoloration of the eyes. She was born at term via uncomplicated vaginal delivery and weighed 3.4 kg (7 lb 8 oz). Her mother did not receive prenatal care. Examination shows scleral icterus and mild hepatosplenomegaly. Laboratory studies show: Hemoglobin 10.7 g/dL Reticulocytes 3.5% Maternal blood group O, Rh-negative Fetal blood group A, Rh-negative Serum bilirubin, total 6.1 mg/dL Serum bilirubin, direct 0.4 mg/dL Which of the following is the most likely cause of this patient's condition?
Viral Infections Indian Medical PG Practice Questions and MCQs
Question 1: LMP 1 gene plays a role in oncogenesis induced by
- A. Hepatitis B virus
- B. Human T cell leukemia virus type 1
- C. Human papilloma virus
- D. Epstein Barr virus (Correct Answer)
Explanation: ***Epstein Barr virus*** - The **LMP1 (Latent Membrane Protein 1)** gene is a key **oncogene** encoded by the **Epstein-Barr virus (EBV)**. - LMP1 acts as a **constitutively active receptor**, mimicking CD40 and leading to the activation of several cellular signaling pathways (**NF-κB, JNK/p38, PI3K/Akt**) crucial for cell proliferation, survival, and differentiation. *Hepatitis B virus* - **Hepatitis B virus (HBV)** is associated with **hepatocellular carcinoma (HCC)**, but its oncogenic mechanisms primarily involve the **HBx protein**, which deregulates cell cycles and impacts host gene expression. - HBV does not encode an LMP1 equivalent; its oncogenesis is linked to chronic inflammation, hepatocyte regeneration, and integration of viral DNA. *Human T cell leukemia virus type 1* - **Human T-cell leukemia virus type 1 (HTLV-1)** is linked to **Adult T-cell Leukemia/Lymphoma (ATL)**, with its primary oncogene being **Tax**. - **Tax protein** activates NF-κB and other pro-proliferative pathways, but HTLV-1 does not have an LMP1 gene. *Human papilloma virus* - **Human papillomavirus (HPV)** is responsible for cervical and other anogenital cancers, with major oncogenes being **E6 and E7**. - **E6 targets p53** for degradation, and **E7 inactivates Rb**, leading to uncontrolled cell division; HPV does not encode an LMP1 gene.
Question 2: How many segments of RNA does the Influenza virus have?
- A. 5 segments of single-stranded RNA
- B. 8 segments of double-stranded DNA
- C. 8 segments of single-stranded DNA
- D. 8 segments of single-stranded RNA (Correct Answer)
Explanation: ***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.
Question 3: A child presented with bluish-white spots in the mouth followed by a rash. What is the genome of the most likely causative agent?
- A. Enveloped virus with single-stranded RNA (Correct Answer)
- B. Double stranded Naked RNA
- C. Naked virus with single-stranded RNA
- D. Double stranded Enveloped RNA
Explanation: ***Enveloped virus with single-stranded RNA*** - Bluish-white spots in the mouth (**Koplik spots**) followed by a rash are pathognomonic for **measles**, which is caused by the **measles virus**. - The measles virus is a **paramyxovirus**, characterized as an **enveloped, negative-sense, single-stranded RNA virus**. *Double stranded Naked RNA* - No major human pathogen belongs to this specific genomic and structural classification. - Most **dsRNA viruses** like **rotavirus** are **naked** but cause gastroenteritis, not measles. *Naked virus with single-stranded RNA* - Viruses like **rhinovirus** (common cold) or **poliovirus** fit this description but do not cause Koplik spots or measles. - **Naked viruses** lack a lipid envelope, making them generally more resistant to environmental factors. *Double stranded Enveloped RNA* - There are no known medically significant human viruses that are both **enveloped** and contain **double-stranded RNA**. - Viral genomes are typically either DNA or RNA, and RNA viruses are usually single-stranded (positive or negative sense) or double-stranded, with or without an envelope.
Question 4: Which of the following diseases has the largest submerged portion in the iceberg model of disease?
- A. Influenza (Correct Answer)
- B. Chickenpox
- C. Tetanus
- D. Rabies
Explanation: **The Iceberg Model of Disease** represents the concept that for many diseases, only a small portion of cases (the "tip" above water) are clinically apparent and reported, while a much larger portion (the "submerged" part) consists of asymptomatic, subclinical, or undiagnosed cases. ***Influenza*** - Has the **largest submerged portion** among the given options, with **50-75% of infections being asymptomatic or mild** and going undiagnosed - High transmissibility and varied clinical presentation contribute to significant hidden burden - Only severe cases requiring hospitalization typically get reported, representing just the "tip of the iceberg" - Classic example of diseases with large subclinical-to-clinical ratio *Chickenpox* - Most cases are **clinically apparent** with characteristic vesicular rash - Asymptomatic infections are rare due to distinctive clinical features - High visibility of cases reduces the submerged portion significantly *Tetanus* - **Severe, acute neurological condition** with distinct clinical manifestations (trismus, risus sardonicus, opisthotonus) - Almost all cases are diagnosed due to dramatic presentation - Virtually no submerged portion - what exists clinically is recognized *Rabies* - **Nearly uniformly fatal** once symptoms appear, making all symptomatic cases clinically evident - No asymptomatic or mild phase after symptom onset - Minimal to no submerged portion in the iceberg model
Question 5: A child presents with a fever and a rash. Urine examination showed cells with owl's eye appearance. What is the most likely diagnosis?
- A. Herpes simplex virus infection
- B. Toxoplasmosis caused by Toxoplasma gondii
- C. Cytomegalovirus (CMV) infection (Correct Answer)
- D. Infectious mononucleosis caused by Epstein-Barr virus
Explanation: ***Cytomegalovirus (CMV) infection*** - The presence of cells with an **owl's eye appearance** in urine sediment is a classic histological hallmark of **CMV infection**. - CMV can cause a variety of symptoms in children, including **fever and rash**, making this the most likely diagnosis. *Herpes simplex virus infection* - HSV causes characteristic **vesicular lesions** on mucocutaneous surfaces, often associated with fever. - While HSV can cause systemic illness, it does not typically present with **owl's eye inclusions** in urine cells. *Toxoplasmosis caused by Toxoplasma gondii* - **Toxoplasmosis** can cause fever and rash, especially in congenital infections or immunocompromised individuals. - However, it does not lead to **owl's eye inclusions** in urinary cells, which are pathognomonic for CMV. *Infectious mononucleosis caused by Epstein-Barr virus* - **Infectious mononucleosis** commonly presents with fever, fatigue, and lymphadenopathy, sometimes with a rash. - **Epstein-Barr virus (EBV)** infection does not produce cells with an **owl's eye appearance** in the urine; that is specific to CMV.
Question 6: The following are true about Epstein-Barr virus (EBV) except which of the following?
- A. Infects epithelial cells of pharynx
- B. It is implicated in nasopharyngeal carcinoma
- C. A member of herpes virus family
- D. The main target of virus is the T-cell lymphocytes (Correct Answer)
Explanation: ***The main target of virus is the T-cell lymphocytes*** - This statement is incorrect because **Epstein-Barr virus (EBV)** primarily targets **B-lymphocytes**, not T-cell lymphocytes. - EBV infects B cells by binding to the **CD21 receptor** on their surface. *A member of herpes virus family* - **EBV** is indeed a member of the **Herpesviridae family**, specifically **gammaherpesvirus**. - Other common herpesviruses include **herpes simplex virus (HSV)** and **cytomegalovirus (CMV)**. *Infects epithelial cells of pharynx* - EBV initially infects and replicates in **epithelial cells of the oropharynx**, contributing to viral shedding in saliva. - This initial infection allows the virus to spread to the targeted B-lymphocytes. *It is implicated in nasopharyngeal carcinoma* - EBV is strongly associated with **nasopharyngeal carcinoma (NPC)**, particularly in endemic regions. - It is also linked to other malignancies like **Burkitt lymphoma** and **Hodgkin lymphoma**.
Question 7: An elderly man who had been in several military conflicts during the early 1980s and received blood transfusions for injuries recently consulted his physician for a diagnosis of cryoglobulinemia and glomerulonephritis. Additional testing revealed that he was infected with a virus transmitted through blood. Which virus was involved in this infection?
- A. Hepatitis A Virus (HAV)
- B. Hepatitis B Virus (HBV)
- C. Hepatitis C Virus (HCV) (Correct Answer)
- D. Hepatitis D Virus (HDV)
Explanation: ***Hepatitis C Virus (HCV)*** - HCV infection is a common cause of **mixed cryoglobulinemia** and can lead to **glomerulonephritis**, particularly membranoproliferative glomerulonephritis. - Before widespread screening of the blood supply, HCV was a significant risk from **blood transfusions**, especially for individuals who received them in the early 1980s [1]. *Hepatitis A Virus (HAV)* - HAV is primarily transmitted via the **fecal-oral route** and does not typically cause chronic infection or lead to cryoglobulinemia or glomerulonephritis. - It causes **acute, self-limiting hepatitis** and is not associated with blood transfusions in the context described. *Hepatitis B Virus (HBV)* - While HBV can be transmitted through blood and can cause glomerulonephritis (e.g., membranous nephropathy), it is less commonly associated with **cryoglobulinemia** in comparison to HCV. - The constellation of cryoglobulinemia and glomerulonephritis, especially with a history of transfusions in the 1980s, points more strongly to HCV. *Hepatitis D Virus (HDV)* - HDV is a **defective virus** that requires co-infection with HBV to replicate. - While it can cause severe liver disease, it is not primarily associated with **cryoglobulinemia** or glomerulonephritis as a direct cause, but rather exacerbates HBV-related complications.
Question 8: 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)
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.
Question 9: A patient presents with a viral infection that shows intranuclear inclusions in epithelial cells on biopsy. Which virus is most likely responsible?
- A. Cytomegalovirus (CMV)
- B. Herpes simplex virus (HSV) (Correct Answer)
- C. Varicella-zoster virus (VZV)
- D. Epstein-Barr virus (EBV)
Explanation: ***Herpes simplex virus (HSV)*** - HSV infection characteristically produces **intranuclear inclusions (Cowdry type A)** and **multinucleated giant cells** in infected epithelial cells [1] - In routine clinical practice, **HSV is the most commonly encountered** virus causing intranuclear inclusions in epithelial cell biopsies - These pathological findings are key for diagnosing HSV infections from mucocutaneous lesions [1] *Cytomegalovirus (CMV)* - CMV does cause prominent intranuclear inclusions in epithelial cells, but characteristically shows the **"owl's eye" appearance** with both large intranuclear inclusions AND prominent cytoplasmic inclusions - Since the question describes only intranuclear inclusions without mentioning the distinctive owl's eye pattern, CMV is less likely - CMV is more commonly seen in immunocompromised patients *Varicella-zoster virus (VZV)* - VZV also produces **intranuclear inclusions (Cowdry type A)** and multinucleated giant cells similar to HSV [2] - However, **HSV is more frequently encountered** in routine epithelial biopsies than VZV - Clinical context and distribution of lesions help differentiate between HSV and VZV [2] *Epstein-Barr virus (EBV)* - EBV primarily infects **B lymphocytes** and oropharyngeal epithelial cells - Unlike other herpesviruses, EBV does **not typically produce characteristic intranuclear inclusions** visible on routine epithelial biopsies - EBV's pathological hallmark is atypical lymphocytosis, not epithelial cytopathic effects **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Infectious Diseases, pp. 365-366. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Infectious Diseases, pp. 366-367.
Question 10: One day after delivery, an African American female newborn develops yellow discoloration of the eyes. She was born at term via uncomplicated vaginal delivery and weighed 3.4 kg (7 lb 8 oz). Her mother did not receive prenatal care. Examination shows scleral icterus and mild hepatosplenomegaly. Laboratory studies show: Hemoglobin 10.7 g/dL Reticulocytes 3.5% Maternal blood group O, Rh-negative Fetal blood group A, Rh-negative Serum bilirubin, total 6.1 mg/dL Serum bilirubin, direct 0.4 mg/dL Which of the following is the most likely cause of this patient's condition?
- A. Transfer of Anti-A antibodies (Correct Answer)
- B. Binding of Rhesus immune globulins
- C. Viral infiltration of the bone marrow
- D. Polymerization of deoxygenated hemoglobin
Explanation: ***Transfer of Anti-A antibodies*** - The mother is **blood group O**, which naturally produces **anti-A and anti-B antibodies**. Since the infant is **blood group A**, these maternal *IgG antibodies* can cross the placenta and cause **hemolysis** in the infant [1], [2]. - This leads to **neonatal jaundice** (due to increased bilirubin from hemolysis) and **anemia** (hemoglobin 10.7 g/dL), with a compensatory **reticulocytosis** (3.5%) [1]. The **splenomegaly** can also be attributed to increased red blood cell destruction [3]. *Binding of Rhesus immune globulins* - The mother is **Rh-negative** and the infant is also **Rh-negative**. Therefore, **Rh incompatibility** is not the cause of the hemolytic disease in this newborn [1]. - **Rhesus immune globulin** is given to **Rh-negative mothers** to prevent alloimmunization against **Rh-positive fetal red blood cells**, which is not relevant here. *Viral infiltration of the bone marrow* - While **viral infections** can cause **hepatosplenomegaly** and **anemia**, they typically suppress red blood cell production, leading to a **low reticulocyte count**, not the **elevated reticulocyte count** seen in this infant. - **Jaundice** associated with viral infections is usually due to **hepatitis** (elevated direct bilirubin), which is not the primary pattern shown here [3]. *Polymerization of deoxygenated hemoglobin* - This process is characteristic of **sickle cell disease**, where **sickle hemoglobin (HbS)** polymerizes, causing red blood cell sickling. - While it can cause **anemia** and **splenomegaly**, it does not typically present as **acute severe jaundice** in the newborn period and is not associated with **ABO incompatibility**.
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