Virology Practice Questions

Q: The most predominant type of polio virus during epidemics is

Type I. ***Type I*** - **Type 1 poliovirus** is historically the most common cause of **paralytic polio** and is responsible for the majority of outbreaks and epidemics globally. - Its high **neurovirulence** and efficient transmission contribute to its predominance in epidemic settings. - **Type 1** accounts for approximately **80-85%** of paralytic polio cases historically. *Type III* - While **Type 3 poliovirus** can cause paralytic polio, it is less frequently isolated during epidemics compared to Type 1. - The last reported case of **wild Type 3 poliovirus** was in November 2012, and it was officially declared eradicated by WHO in October 2019. *Type II* - **Type 2 poliovirus** is associated with a lower incidence of **paralytic disease** and was declared eradicated in September 2015. - It is no longer found in **wild circulation** and is not the predominant type in current epidemics. *Combined infection of II & III* - While co-infections with different poliovirus types were possible historically, **Type 1** remains the single most common and predominant type during epidemics, driving the majority of cases. - **Type 2** and **Type 3** wild polioviruses have been eradicated, making combined wild-type infections impossible in current global epidemiology.

Q: Group of viruses that inhabit the alimentary tract of children below 2 years age:

Coxsackie virus. ***Coxsackie virus*** - **Coxsackieviruses** are a common cause of infections in young children, often leading to conditions like **hand-foot-and-mouth disease** or herpangina, which involve the alimentary tract. - These viruses replicate in the **gastrointestinal tract** and are a frequent cause of viral infections in children under two years of age. *Varicella zoster virus* - This virus is responsible for **chickenpox** and **shingles**, primarily affecting the skin and nervous system, not typically inhabiting the alimentary tract as its primary site of replication or causing symptoms in the gut. - While it can be found in the body, it is not a virus group commonly associated with routine alimentary tract habitation in young children in the way enteroviruses are. *Herpes simplex virus* - **HSV-1** and **HSV-2** primarily cause mucocutaneous lesions (e.g., cold sores, genital herpes) and can cause encephalitis, but they do not typically colonize or primarily inhabit the alimentary tract of children. - While oral HSV-1 infections are common in children, the virus's primary tropism is for **neural tissue** and epithelial cells, not a general alimentary tract dwelling. *Paramyxovirus* - This family includes viruses like **measles, mumps, and respiratory syncytial virus (RSV)**, which primarily cause respiratory infections and systemic diseases. - They are not known for inhabiting the alimentary tract of children as their main site of infection or replication in the same manner as enteroviruses.

Q: Japanese encephalitis is caused by -

Flavivirus. ***Flavivirus*** - **Japanese encephalitis** is an **arboviral disease** caused by the **Japanese encephalitis virus (JEV)**, which belongs to the genus *Flavivirus* within the family *Flaviviridae*. - This **RNA virus** is primarily transmitted to humans through the bite of infected mosquitoes. *Culex* - While mosquitoes of the genus *Culex* (especially *Culex tritaeniorhynchus*) are the **primary vectors** that transmit the Japanese encephalitis virus, they are not the causative agent themselves. - *Culex* mosquitoes acquire the virus from infected animals and then transmit it to humans. *Pigs* - **Pigs** are considered **amplifying hosts** for the Japanese encephalitis virus, meaning the virus replicates to high levels in them and can then infect mosquitoes. - However, pigs do not directly cause the disease in humans; they act as a reservoir in the transmission cycle. *None of the options* - This option is incorrect as **Flavivirus** is indeed the causative agent of Japanese encephalitis.

Q: All of the following are true statements for Arbovirus EXCEPT:

Kyasanur Forest Disease is transmitted by mites. ***Kyasanur Forest Disease is transmitted by mites*** - This statement is **false**. Kyasanur Forest Disease (KFD) is transmitted by **ticks**, specifically the *Haemaphysalis spinigera* tick, not mites. - KFD is a **tick-borne viral hemorrhagic fever** endemic to certain regions of India, caused by a flavivirus. *West nile fever is transmitted by Culex mosquito* - This statement is **true**. **West Nile virus** is primarily transmitted to humans through the bite of infected mosquitos, mainly species of **Culex**. - The virus circulates naturally between mosquitos and **birds**, with humans being incidental hosts. *Chikungunya fever is transmitted by Aedes mosquito* - This statement is **true**. **Chikungunya virus** is transmitted to humans through the bites of infected female mosquitos, primarily **Aedes aegypti** and **Aedes albopictus**. - These mosquitos are also vectors for other diseases such as dengue and Zika. *Japanese encephalitis is caused by group B Arbovirus (Flavivirus)* - This statement is **true**. Japanese encephalitis is caused by the **Japanese encephalitis virus (JEV)**, which belongs to the **Flaviviridae family**, often referred to as group B Arboviruses. - Most human infections are asymptomatic, but severe cases can lead to **encephalitis** with high mortality.

Q: Which of the following statements about Prions is true:

They are infectious proteins. ***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.

Q: Multinucleated giant cells are seen in smear from the lesions of:

Herpes simplex virus. ***Herpes simplex virus*** - **Multinucleated giant cells** with intranuclear inclusions are characteristic findings in Tzanck smears from **herpes simplex virus (HSV)** lesions [1]. - This cellular morphology results from the fusion of infected cells, a cytopathic effect of the virus [1]. *HIV* - HIV primarily infects **CD4+ T-cells** and macrophages, leading to immunosuppression, but does not typically cause multinucleated giant cells in skin lesion smears. - While HIV can be associated with various opportunistic skin lesions, the hallmark cytological finding from the primary infection itself is not multinucleated giant cells. *Poliovirus* - Poliovirus is an **enterovirus** that primarily affects the central nervous system, causing paralytic disease. - It does not cause skin lesions characterized by multinucleated giant cells. *Rabiesvirus* - Rabiesvirus is a **neurotropic virus** that causes acute encephalitis in mammals. - The characteristic pathological finding in rabies is the presence of **Negri bodies** (intracytoplasmic inclusions) in neurons, not multinucleated giant cells in skin smears. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Infectious Diseases, pp. 365-366.

Q: A young pregnant woman presents with fulminant hepatic failure. The most likely aetiological agent is -

Hepatitis E virus. ***Hepatitis E virus*** - **Hepatitis E virus (HEV)** infection is known to cause **fulminant hepatic failure** in pregnant women, leading to high maternal and fetal mortality rates. - The severity of HEV infection is significantly increased during pregnancy, particularly in the third trimester. *Hepatitis A virus* - **Hepatitis A virus (HAV)** typically causes an acute, self-limiting hepatitis and rarely leads to fulminant hepatic failure, even in pregnant women. - While HAV can impact pregnancy outcomes, the incidence of fulminant failure is much lower compared to HEV. *Hepatitis B virus* - **Hepatitis B virus (HBV)** infection can cause chronic hepatitis and cirrhosis, but acute HBV infection rarely results in fulminant hepatic failure during pregnancy. - The primary concern with HBV in pregnancy is vertical transmission to the neonate. *Hepatitis C virus* - **Hepatitis C virus (HCV)** infection often leads to chronic hepatitis and can progress to cirrhosis and hepatocellular carcinoma over decades. - Acute HCV infection rarely causes fulminant hepatic failure, and its impact on pregnancy is usually less severe in terms of acute liver failure compared to HEV.

Q: Exanthema subitum is caused by -

HHV. ***HHV*** - **Exanthema subitum**, also known as **roseola infantum**, is most commonly caused by **Human Herpesvirus 6 (HHV-6)** and sometimes **Human Herpesvirus 7 (HHV-7)**. - It is characterized by high fever followed by a **maculopapular rash** once the fever subsides. *HIV* - **Human Immunodeficiency Virus (HIV)** causes **Acquired Immunodeficiency Syndrome (AIDS)**, leading to a weakened immune system. - While HIV can cause various skin manifestations, **exanthema subitum** is not one of its primary or characteristic presentations. *HCV* - **Hepatitis C Virus (HCV)** primarily causes **hepatitis**, infecting the liver and potentially leading to chronic liver disease. - HCV is not known to cause **exanthema subitum** or similar childhood exanthems. *HPV* - **Human Papillomavirus (HPV)** is responsible for **warts** and certain **cancers**, particularly cervical cancer. - HPV does not cause **exanthema subitum**; its manifestations are typically localized to skin and mucous membranes as proliferative lesions.

Q: Which of the following is the prototype arboviral disease?

Yellow fever. ***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.

Q: True about prions are all except -

Cannot be inherited. ***Cannot be inherited*** - This statement is **false** because prion diseases, such as **familial Creutzfeldt-Jakob disease (fCJD)** and **Gerstmann-Sträussler-Scheinker syndrome (GSS)**, can indeed be inherited due to mutations in the **PRNP gene**. - These genetic mutations lead to the production of an abnormal prion protein, PrPSc, which can then misfold and cause disease. *Can be transmitted by corneal transplant* - **Prion diseases** can be transmitted through corneal transplants, as the **cornea** can harbor infectious prions. - This route of transmission is an example of **iatrogenic CJD**, highlighting the importance of cautious donor screening. *Can occur sporadically* - The most common form of human prion disease, **sporadic Creutzfeldt-Jakob disease (sCJD)**, occurs without any known genetic mutation or environmental exposure. - This accounts for about 85-90% of all CJD cases, where the initial misfolding of the prion protein is spontaneous. *Can be transmitted by human growth hormone preparation* - **Iatrogenic Creutzfeldt-Jakob disease (iCJD)** has been linked to the use of human growth hormone preparations derived from cadaveric pituitary glands. - Before the advent of recombinant human growth hormone, these preparations could transmit prions from infected donors.

Question 1

The most predominant type of polio virus during epidemics is

Accepted Answer

Type I

Answer

Type III

Answer

Type II

Answer

Combined infection of II & III

Question 2

Group of viruses that inhabit the alimentary tract of children below 2 years age:

Accepted Answer

Coxsackie virus

Answer

Varicella zoster virus

Answer

Herpes simplex virus

Answer

Paramyxovirus

Question 3

Japanese encephalitis is caused by -

Accepted Answer

Flavivirus

Answer

Culex

Answer

Pigs

Answer

None of the options

Question 4

All of the following are true statements for Arbovirus EXCEPT:

Accepted Answer

Kyasanur Forest Disease is transmitted by mites

Answer

West nile fever is transmitted by Culex mosquito

Answer

Chikungunya fever is transmitted by Aedes mosquito

Answer

Japanese encephalitis is caused by group B Arbovirus (Flavivirus)

Question 5

Which of the following statements about Prions is true:

Accepted Answer

They are infectious proteins

Answer

They can be cultured in cell free media

Answer

They have rich nuclear material

Answer

They are made up of bacteria and virus

Question 6

Multinucleated giant cells are seen in smear from the lesions of:

Accepted Answer

Herpes simplex virus

Answer

HIV

Answer

Poliovirus

Answer

Rabiesvirus

Question 7

A young pregnant woman presents with fulminant hepatic failure. The most likely aetiological agent is -

Accepted Answer

Hepatitis E virus

Answer

Hepatitis A virus

Answer

Hepatitis B virus

Answer

Hepatitis C virus

Question 8

Exanthema subitum is caused by -

Accepted Answer

HHV

Answer

HIV

Answer

HCV

Answer

HPV

Question 9

Which of the following is the prototype arboviral disease?

Accepted Answer

Yellow fever

Answer

Trench fever

Answer

Epidemic typhus

Answer

Japanese encephalitis

Question 10

True about prions are all except -

Accepted Answer

Cannot be inherited

Answer

Can be transmitted by corneal transplant

Answer

Can occur sporadically

Answer

Can be transmitted by human growth hormone preparation

Virology — MCQs

Virology — MCQs

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