Virology — MCQs

Virology Indian Medical PG Practice Questions and MCQs

Question 1271: Which of the following statements about Prions is true:

A. They can be cultured in cell free media
B. They are infectious proteins (Correct Answer)
C. They have rich nuclear material
D. They are made up of bacteria and virus

Explanation: ***They are infectious proteins*** - Prions are uniquely characterized as **infectious proteinaceous particles** that lack nucleic acids. - Their mechanism of pathogenicity involves inducing conformational changes in normal host proteins, leading to disease. *They can be cultured in cell free media* - Prions cannot be cultured in cell-free media because they are **not living organisms** and require host cells to propagate by converting normal proteins. - Their replication depends on the presence of the **normal prion protein (PrPC)** in the host. *They have rich nuclear material* - Prions are fundamentally **devoid of nucleic acids** (DNA or RNA), which is a defining characteristic distinguishing them from viruses, bacteria, and other microorganisms. - Their infectious nature is solely based on their **aberrant protein structure**. *They are made up of bacteria and virus* - Prions are distinct biological entities that are **neither bacteria nor viruses**; they are misfolded proteins. - They are much simpler in structure than even the smallest viruses, lacking the complex genetic material and cellular machinery found in bacteria and viruses.

Question 1272: 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 1273: Which of the following is the prototype arboviral disease?

A. Trench fever
B. Epidemic typhus
C. Japanese encephalitis
D. Yellow fever (Correct Answer)

Explanation: ***Yellow fever*** - Yellow fever is historically and medically significant as the **first human disease** identified as arboviral. - It is transmitted by **Aedes aegypti mosquitoes** and is caused by an RNA virus of the genus **Flavivirus**. *Trench fever* - Trench fever is caused by the bacterium **Bartonella quintana**, not a virus. - It is transmitted by the **human body louse** (Pediculus humanus corporis), making it a rickettsial disease, not arboviral. *Epidemic typhus* - Epidemic typhus is caused by the bacterium **Rickettsia prowazekii** and is primarily transmitted by the **human body louse**. - It is a **rickettsial disease**, not an arboviral disease, which involves arthropod vectors like mosquitoes or ticks. *Japanese encephalitis* - While Japanese encephalitis is an important arboviral disease transmitted by **Culex mosquitoes**, it was identified much later than yellow fever. - It is a severe viral infection of the brain, but **yellow fever holds the distinction** of being the prototype.

Question 1274: Ramsay Hunt syndrome is caused by:

A. Herpes simplex
B. Herpes zoster (Correct Answer)
C. Influenza
D. Adenovirus

Explanation: ***Correct Answer: Herpes zoster*** - **Ramsay Hunt syndrome (Herpes Zoster Oticus)** is caused by the reactivation of the **varicella-zoster virus (VZV)**, the same virus that causes chickenpox and shingles. - The reactivation specifically affects the **geniculate ganglion** of the facial nerve, leading to the classic triad: facial paralysis, ear pain, and a vesicular rash in the ear canal. - Key clinical features include **auricular vesicles**, **facial nerve palsy**, and **severe otalgia**. *Incorrect: Herpes simplex* - **Herpes simplex virus (HSV)** causes oral and genital herpes, and in some cases can lead to encephalitis or Bell's palsy, but not Ramsay Hunt syndrome. - While HSV can cause facial paralysis (Bell's palsy), it typically does not present with the characteristic vesicular rash in the ear canal or severe otalgia seen in Ramsay Hunt syndrome. *Incorrect: Influenza* - **Influenza virus** primarily causes respiratory infections with symptoms like fever, cough, and body aches. - It does not cause facial nerve paralysis or vesicular rashes characteristic of Ramsay Hunt syndrome. *Incorrect: Adenovirus* - **Adenoviruses** are a common cause of respiratory illnesses, conjunctivitis, and gastroenteritis. - They are not associated with cranial nerve palsies or the dermatological manifestations seen in Ramsay Hunt syndrome.

Question 1275: Which of the following markers in the blood is the most reliable indicator of recent hepatitis B infection?

A. anti-HBe
B. HBsAg
C. IgG anti - HBs
D. IgM anti - HBc (Correct Answer)

Explanation: ***IgM anti - HBc*** - **IgM anti-HBc** (antibody to hepatitis B core antigen) is the most reliable marker for **recent or acute hepatitis B infection**. - It appears early in the infection and can be detected during the **window period** when HBsAg may have disappeared but anti-HBs has not yet appeared. *anti-HBe* - **Anti-HBe** (antibody to hepatitis B e-antigen) indicates **lower infectivity** and often suggests resolution of viral replication. - It usually appears after HBeAg disappears and is not a primary marker of recent infection. *HBsAg* - **HBsAg** (hepatitis B surface antigen) indicates active **hepatitis B infection** (acute or chronic), but does not differentiate recent from long-standing infection on its own. - While present in recent infection, IgM anti-HBc is more specific for **acute or recent onset**. *IgG anti - HBs* - **IgG anti-HBs** (antibody to hepatitis B surface antigen) indicates either **recovery from past infection** or **immunity due to vaccination**. - It does not signify recent infection; rather, it suggests long-term immunity.

Question 1276: Swine Flu pandemic in 2009 was caused due to which strain:

A. H5N1
B. H1N1 (Correct Answer)
C. H3N1
D. H7N1

Explanation: ***H1N1*** - The 2009 **Swine Flu pandemic** was caused by a novel strain of **influenza A virus** designated as **H1N1**. - This virus was a reassortant strain with genes from **swine, avian, and human influenza viruses**. *H5N1* - **H5N1** is known as the **Avian Influenza** or **Bird Flu** and has caused outbreaks primarily in poultry and some human cases, but was not responsible for the 2009 pandemic. - While concerning due to its high pathogenicity in birds and potential for transmission to humans, it did not achieve **sustained human-to-human transmission** like H1N1. *H3N1* - **H3N1** is an influenza A subtype that is not commonly associated with **major human pandemics**. - While influenza viruses constantly mutate, **H3N1** did not cause the 2009 Swine Flu pandemic. *H7N1* - **H7N1** is another influenza A subtype that can cause outbreaks, primarily in **birds**. - It has not been identified as the cause of widespread human pandemics like the **2009 H1N1 event**.

Question 1277: False about antigenic drift-

A. Affected by previous antibodies
B. Occurs due to mutation
C. Causes pandemic (Correct Answer)
D. Occurs more frequently

Explanation: ***Causes pandemic*** - **Antigenic drift** involves minor changes in surface antigens that may lead to localized outbreaks or epidemics, usually not global pandemics. - **Antigenic shift**, which involves major changes, is typically responsible for causing pandemics. *Affected by previous antibodies* - Antigenic drift results in minor changes in **surface antigens**, allowing the virus to evade existing antibodies partially. - This means individuals with prior immunity or vaccination may still be susceptible to infection, though the disease might be milder. *Occurs due to mutation* - **Antigenic drift** is caused by point mutations in the genes encoding surface antigens like **hemagglutinin (HA)** and **neuraminidase (NA)**. - These mutations accumulate over time, leading to gradual changes in the viral antigens. *Occurs more frequently* - **Antigenic drift** occurs continually and frequently, particularly in influenza viruses, leading to the need for annual vaccine updates. - This continuous process of minor antigenic changes is why influenza vaccines are reformulated each year.

Question 1278: Infective diarrhea is caused by all except -

A. Flavivirus (Correct Answer)
B. Enterovirus
C. Calicivirus
D. Rotavirus

Explanation: ***Flavivirus*** - **Flaviviruses** are primarily associated with arthropod-borne diseases like **dengue fever**, **Zika virus**, and **yellow fever**, which typically manifest with fever, rash, and hemorrhagic symptoms, rather than infective diarrhea. - While some gastrointestinal symptoms can occur with flaviviruses, infective diarrhea is not their primary or defining clinical presentation. *Enterovirus* - **Enteroviruses** can cause a variety of clinical syndromes, including **gastroenteritis**, with symptoms like diarrhea, nausea, and vomiting. - Examples include **Coxsackievirus** and **Echovirus**, which are well-known causes of viral diarrhea, especially in children. *Calicivirus* - **Caliciviruses**, particularly **Norovirus** (a type of calicivirus), are a leading cause of **epidemic non-bacterial gastroenteritis** in adults and children worldwide. - They commonly cause acute onset of vomiting, watery diarrhea, and abdominal cramps. *Rotavirus* - **Rotavirus** is a major cause of **severe, watery diarrhea** and vomiting in infants and young children globally. - It replicates in the small intestine, damaging enterocytes and leading to malabsorption and increased fluid secretion.

Question 1279: Herpangina is caused by the virus -

A. Group A Coxsackie (Correct Answer)
B. Group B Coxsackie
C. Adenovirus
D. Measles

Explanation: ***Group A Coxsackie*** - Herpangina is a common viral illness characterized by small, painful ulcers on the **soft palate** and tonsillar pillars, predominantly caused by various serotypes of **Coxsackievirus group A**, particularly A1-A10, A16, and A22. - This **enterovirus** infection is highly contagious and often seen in infants and young children, especially during summer and fall. *Group B Coxsackie* - **Group B Coxsackieviruses** are primarily associated with diseases like **pleurodynia** (**Bornholm disease**), myocarditis, and pericarditis, rather than herpangina. - While both Group A and B Coxsackieviruses are enteroviruses, their typical clinical manifestations differ significantly. *Adenovirus* - **Adenoviruses** are known to cause a range of illnesses, including respiratory infections (**pharyngitis**, pneumonia), conjunctivitis, and gastroenteritis. - They are not typically implicated in the etiology of herpangina, which is characterized by specific oral lesions. *Measles* - **Measles virus** (a paramyxovirus) causes measles, a highly contagious systemic illness characterized by a generalized maculopapular rash, cough, coryza, and conjunctivitis, along with **Koplik spots** in the mouth. - Measles does not cause the vesicular and ulcerative lesions seen in herpangina; Koplik spots are distinct enanthem findings.

Question 1280: Hand-foot-mouth disease is caused by:

A. Coxsackie-B virus
B. EBV
C. CMV
D. Coxsackie-A virus (Correct Answer)

Explanation: ***Coxsackie-A virus*** - Hand-foot-mouth disease (HFMD) is most commonly caused by **Coxsackievirus A16** within the species **Human enterovirus A**. - Other **Coxsackievirus A serotypes** can also cause HFMD, particularly **A6, A10**, and **Enterovirus A71**. *Coxsackie-B virus* - **Coxsackievirus B** is known to cause a range of illnesses, including **myocarditis**, **pleurodynia (Bornholm disease)**, and **pericarditis**. - While it belongs to the same genus (Enterovirus), it is not the typical causative agent of HFMD. *EBV* - **Epstein-Barr Virus (EBV)** is a herpesvirus that causes **infectious mononucleosis**, **Burkitt's lymphoma**, and **nasopharyngeal carcinoma**. - It is transmitted through saliva and is **not associated with HFMD**. *CMV* - **Cytomegalovirus (CMV)** is a common virus that can cause a wide spectrum of diseases, especially in immunocompromised individuals and congenitally. - It is known for causing mononucleosis-like syndrome, congenital infections, and retinitis, but it is **not associated with HFMD**.

Practice by Chapter

Virus Structure and Classification

Practice Questions

Viral Replication

Practice Questions

Pathogenesis of Viral Infections

Practice Questions

DNA Viruses: Herpesviruses

Practice Questions

DNA Viruses: Poxviruses and Adenoviruses

Practice Questions

Hepatitis Viruses

Practice Questions

RNA Viruses: Orthomyxoviruses

Practice Questions

RNA Viruses: Paramyxoviruses

Practice Questions

Enteroviruses and Rhinoviruses

Practice Questions

Arboviruses

Practice Questions

HIV and Retroviruses

Practice Questions

Oncogenic Viruses

Practice Questions

Want unlimited practice?

Get full access to all questions, explanations, and performance tracking.

Start For Free

Virology — MCQs

Virology — MCQs

On this page

Practice by Chapter

Want unlimited practice?