Virology Practice Questions

Q: A blood donor is not considered for safe transfusion if he has:

HBsAg +ve and IgM anti-HBc +ve. ***HBsAg +ve and IgM anti-HBc +ve*** - A positive **HBsAg** indicates current hepatitis B infection, making the donor unsuitable for transfusion due to the risk of transmission [2]. - The presence of **IgM anti-HBc** further confirms a recent or acute infection, enhancing the risk of infectivity [2], [3]. *Anti-HBc +ve* - A positive **anti-HBc** (total) alone can indicate a past resolved infection or chronic infection, but does not always rule out donation, especially if HBsAg is negative and anti-HBs is positive [3]. - In many settings, donors with isolated anti-HBc positive results might be deferred, but it's not as definitive a contraindication as HBsAg positivity. *Anti-HBsAg +ve* - A positive **anti-HBsAg** (HBsAb) indicates immunity to hepatitis B, either due to vaccination or past resolved infection [3]. - Donors with only anti-HBsAg positivity are generally considered safe for transfusion as they are not infectious and may even provide protective antibodies [1]. *Anti-HBsAg and anti-HBc (+)ve* - This profile typically indicates a **resolved hepatitis B infection** with established immunity [3]. - Such individuals are considered safe donors as they are not actively infected and pose no risk of transmitting hepatitis B [1].

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

H1N1. ***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**.

Q: The presence of which of the following factors in viruses makes protective vaccines a possibility?

Protein coat. ***Protein coat*** - The **protein coat** (capsid) of viruses contains **antigenic proteins** that can be recognized by the host immune system. - Vaccines work by exposing the immune system to these viral proteins, stimulating the production of **antibodies** and memory cells for future protection. *Lipids* - While some viruses have a **lipid envelope**, lipids themselves are generally **poor antigens** and do not effectively stimulate a protective immune response on their own. - The immune response against enveloped viruses is primarily directed at the **glycoproteins** embedded within the lipid envelope, not the lipids themselves. *Enzymes* - Viruses contain various enzymes (e.g., reverse transcriptase, RNA polymerase) essential for their replication, but these are typically **intracellular targets**. - **Enzymes** are not usually present on the viral surface in an exposed manner that would consistently trigger a protective antibody response. *Polysaccharide* - **Polysaccharides** are common components of bacterial capsules but are generally **not significant components** of viral structure. - Viruses are primarily composed of nucleic acids and proteins, and the immune response to viruses rarely involves polysaccharides.

Q: The etiological agent for roseola infantum is:

Human Herpesvirus 6 (HHV-6). ***Human Herpesvirus 6 (HHV-6)*** - **HHV-6** is the primary cause of **roseola infantum**, also known as exanthem subitum. - This virus is responsible for the characteristic high fever followed by a rash often seen in infants and young children. *Epstein-Barr Virus (EBV)* - **EBV** is the causative agent of **infectious mononucleosis**, not roseola infantum. - While both are herpesviruses, their clinical presentations and target cell specificities differ significantly. *Cytomegalovirus (CMV)* - **CMV** is another herpesvirus that can cause a variety of symptoms, especially in immunocompromised individuals or congenitally. - It is not typically associated with the classic presentation of **roseola infantum**. *Adenovirus* - **Adenoviruses** are a common cause of respiratory infections, conjunctivitis, and gastroenteritis. - They do not cause **roseola infantum**, which is characterized by a specific fever-rash sequence.

Q: False about antigenic drift-

Causes pandemic. ***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.

Q: Infective diarrhea is caused by all except -

Flavivirus. ***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.

Q: All are caused by Parvo virus infection except:

Gianotti crosti syndrome. ***Gianotti crosti syndrome*** - This syndrome is typically caused by **Epstein-Barr virus**, **Hepatitis B virus**, coxsackievirus, echovirus, or enterovirus, NOT parvovirus B19. - It presents with a **papulovesicular rash** mainly on the face, buttocks, and extremities, often linked to distinct viral etiologies. *Aplastic crisis* - **Parvovirus B19** has a tropism for **erythroid progenitor cells**, causing their destruction and leading to temporary cessation of red blood cell production [1]. - This can precipitate an **aplastic crisis**, especially in individuals with underlying hemolytic anemias like sickle cell disease [1]. *Papular- purpuric gloves and socks syndrome (PPGSS)* - PPGSS is a rare but characteristic manifestation of **Parvovirus B19** infection, presenting with a sharply demarcated papular-purpuric rash. - The rash typically affects the **hands ("gloves") and feet ("socks")**, often accompanied by fever and oral erosions. *Erythema infectiosum* - Also known as **Fifth Disease**, this is a common benign childhood rash caused by **Parvovirus B19** [1]. - It presents with a characteristic **"slapped cheek" rash** on the face, followed by a lacy, reticular rash on the trunk and extremities [1].

Q: Herpangina is caused by the virus -

Group A Coxsackie. ***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.

Q: Cataracts and PDA in a newborn suggests in utero infection with which viral family?

Togavirus. ***Togavirus*** is the correct answer. **Congenital rubella syndrome**, caused by the **rubella virus** (family Togaviridae), is classically associated with the triad of **cataracts**, **patent ductus arteriosus (PDA)**, and **sensorineural hearing loss**. The virus crosses the placenta and can cause widespread damage to the developing fetus, particularly during the first trimester when organogenesis occurs. *Adenovirus* is incorrect. Adenoviruses typically cause respiratory tract infections, conjunctivitis, and gastroenteritis in newborns, but are not known to cause congenital abnormalities like cataracts and PDA. While they can infect newborns, their presentation does not include the specific congenital malformations seen with rubella. *Paramyxovirus* is incorrect. The Paramyxovirus family includes viruses like measles and mumps, which can cause severe infections but are not typically associated with congenital cataracts and PDA. Measles can lead to complications in pregnancy such as preterm birth or miscarriage, but not the specific triad of congenital rubella syndrome. *Picornavirus* is incorrect. The Picornavirus family includes enteroviruses (like poliovirus, coxsackievirus) and rhinovirus. While some enteroviruses can cause severe systemic infections in newborns (e.g., myocarditis with coxsackievirus), they are not primarily associated with cataracts and PDA as congenital anomalies.

Q: Hand-foot-mouth disease is caused by:

Coxsackie-A virus. ***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**.

Question 1

A blood donor is not considered for safe transfusion if he has:

Accepted Answer

HBsAg +ve and IgM anti-HBc +ve

Answer

Anti-HBc +ve

Answer

Anti-HBsAg +ve

Answer

Anti-HBsAg and anti-HBc (+)ve

Question 2

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

Accepted Answer

H1N1

Answer

H5N1

Answer

H3N1

Answer

H7N1

Question 3

The presence of which of the following factors in
viruses makes protective vaccines a possibility?

Accepted Answer

Protein coat

Answer

Lipids

Answer

Enzymes

Answer

Polysaccharide

Question 4

The etiological agent for roseola infantum is:

Accepted Answer

Human Herpesvirus 6 (HHV-6)

Answer

Epstein-Barr Virus (EBV)

Answer

Cytomegalovirus (CMV)

Answer

Adenovirus

Question 5

False about antigenic drift-

Accepted Answer

Causes pandemic

Answer

Affected by previous antibodies

Answer

Occurs due to mutation

Answer

Occurs more frequently

Question 6

Infective diarrhea is caused by all except -

Accepted Answer

Flavivirus

Answer

Enterovirus

Answer

Calicivirus

Answer

Rotavirus

Question 7

All are caused by Parvo virus infection except:

Accepted Answer

Gianotti crosti syndrome

Answer

Aplastic crisis

Answer

Papular- purpuric gloves and socks syndrome (PPGSS)

Answer

Erythema infectiosum

Question 8

Herpangina is caused by the virus -

Accepted Answer

Group A Coxsackie

Answer

Group B Coxsackie

Answer

Adenovirus

Answer

Measles

Question 9

Cataracts and PDA in a newborn suggests in utero infection with which viral family?

Accepted Answer

Togavirus

Answer

Adenovirus

Answer

Paramyxovirus

Answer

Picornavirus

Question 10

Hand-foot-mouth disease is caused by:

Accepted Answer

Coxsackie-A virus

Answer

Coxsackie-B virus

Answer

EBV

Answer

CMV

Virology — MCQs

Virology — MCQs

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