Virology Practice Questions

Q: Shingles is caused by infection with:

Varicella zoster virus. ***Varicella zoster virus*** - **Varicella zoster virus (VZV)** is the causative agent of both **chickenpox** (varicella) and **shingles** (herpes zoster). - Shingles occurs due to the **reactivation** of latent VZV from sensory ganglia, years after a primary chickenpox infection. *Epstein-Barr virus* - **Epstein-Barr virus (EBV)** is responsible for **infectious mononucleosis** and is associated with several malignancies. - It does not cause shingles or any other **herpes zoster**-like syndrome. *Human papilloma virus* - **Human papilloma virus (HPV)** is known for causing **warts** and is a primary cause of **cervical cancer**. - HPV is not related to the pathogenesis of shingles. *Herpes simplex virus* - **Herpes simplex virus (HSV)** causes **oral herpes** (cold sores) and **genital herpes**. - While it belongs to the same family (Herpesviridae) as VZV, it causes different clinical manifestations and is distinct from the virus causing shingles.

Q: Which is the most common mode of transmission of HSV-1?

Saliva. ***Saliva*** - HSV-1 is primarily transmitted through **oral secretions**, such as saliva, due to close personal contact like **kissing** or sharing utensils. - The virus is present in the saliva of infected individuals, even in the absence of active lesions, facilitating its widespread transmission. *Placental transmission* - While possible, **vertical transmission** of HSV (primarily HSV-2) from mother to fetus via the placenta is rare and typically leads to **neonatal herpes**, not the most common mode of HSV-1 infection. - This mode is more characteristic of infections like **cytomegalovirus** or **syphilis**. *Sexual transmission* - While HSV-1 can cause **genital herpes** and be transmitted sexually, it is not its most common mode of acquisition, especially in childhood. - **HSV-2** is the primary cause of genital herpes and is predominantly transmitted through sexual contact. *Blood* - HSV is not typically transmitted through **blood transfusions** or contact with blood products. - While theoretical, **viremia** (virus in the blood) in HSV infections is transient and less significant for transmission compared to direct contact with active lesions or secretions.

Q: Influenza pandemics are most commonly caused by-

Influenza-A. ***Influenza-A*** - **Influenza A viruses** are responsible for causing **all known influenza pandemics** due to their ability to undergo **antigenic shift**. - Antigenic shift involves major genetic reassortment, particularly in the hemagglutinin (H) and neuraminidase (N) surface proteins, allowing the virus to evade host immunity and cause widespread infection. - Historical pandemics (1918 Spanish flu, 1957 Asian flu, 1968 Hong Kong flu, 2009 H1N1) were all caused by Influenza A. *Influenza-C* - **Influenza C viruses** are generally associated with **mild, self-limiting respiratory illnesses** and do not typically cause epidemics or pandemics. - The genome of Influenza C viruses is less prone to the significant genetic changes necessary to cause pandemics. *Influenza-D* - **Influenza D viruses** primarily infect **cattle and other livestock** and have not been shown to cause human infections. - They are not associated with human epidemics or pandemics. *Influenza-B* - While **Influenza B viruses** can cause seasonal epidemics, they do not undergo **antigenic shift** to the same extent as Influenza A. - Influenza B viruses only circulate in humans and lack the animal reservoir necessary for major reassortment events. - This limited genetic variability means they are **not typically associated with pandemics**.

Q: An 8-year-old boy presented with swelling on both sides of the face, below the ears of 4 days duration. It first started on the left side and then 3 days later on the right side. Cause for the disease will be

Paramyxovirus. ***Paramyxovirus*** - The classic presentation of **bilateral parotid swelling** in a child, starting unilaterally and then becoming bilateral, is highly suggestive of **mumps**, which is caused by the paramyxovirus (family Paramyxoviridae). - Mumps is a **contagious viral infection** that primarily affects the salivary glands, particularly the parotid glands. - The characteristic feature is **sequential bilateral involvement**, typically with 1-5 days between sides. *Herpes simplex virus* - Herpes simplex virus (HSV) typically causes **oral or genital lesions** (cold sores, blisters) or encephalitis, not diffuse salivary gland swelling. - HSV does not commonly present with **parotitis**, the hallmark symptom described in the clinical vignette. *Cytomegalovirus* - Cytomegalovirus (CMV) is a common viral infection that can cause a **mononucleosis-like syndrome** or congenital infections, especially in immunocompromised individuals. - While CMV can rarely cause sialadenitis, it is not the typical or most common cause of the described presentation of **acute, bilateral parotitis** in an otherwise healthy child. *Hepatitis C virus* - Hepatitis C virus primarily causes **liver inflammation** (hepatitis) and is associated with chronic liver disease, cirrhosis, and hepatocellular carcinoma. - It does not typically cause **acute salivary gland swelling** as described in the clinical scenario.

Q: Dangerous type of Herpes virus -

Herpes virus simiae. ***Herpes virus simiae*** - **Herpes virus simiae**, also known as **B virus**, is extremely dangerous to humans, often leading to severe neurological disease or death if an infection occurs. - It is naturally found in **macaques** and can be transmitted to humans through bites, scratches, or exposure to infected tissues or fluids. *Cytomegalovirus* - **Cytomegalovirus (CMV)** is generally benign in healthy individuals, causing mild or asymptomatic infections. - While CMV can be severe in immunocompromised patients or neonates (leading to **congenital CMV**), it is not inherently as dangerous as Herpes virus simiae in healthy individuals. *Epstein Barr virus* - **Epstein-Barr virus (EBV)** is famous for causing **infectious mononucleosis** in humans. - Although it can be associated with certain cancers like **Burkitt lymphoma** and **nasopharyngeal carcinoma**, it is not acutely "dangerous" in the same immediate, life-threatening way as Herpes virus simiae upon initial infection in healthy hosts. *Herpes simplex-2* - **Herpes simplex virus type 2 (HSV-2)** is the primary cause of genital herpes. - While it causes recurrent, painful lesions and can lead to **neonatal herpes** (which is serious), it does not typically cause the rapid, fatal neurological disease seen with Herpes virus simiae in humans.

Q: Antigenic shift and drift occur in

Influenza. ***Influenza*** - Influenza viruses undergo both **antigenic drift** (minor mutations in surface antigens, leading to new seasonal strains) and **antigenic shift** (major genetic reassortment, leading to novel strains like pandemic flu). - These mechanisms allow the virus to **evade host immunity**, necessitating frequent vaccine updates. *Rubella* - The rubella virus (German measles) is a **Togavirus** that is generally genetically stable. - It does not exhibit significant antigenic drift or shift, which is why a single **MMR vaccine** provides long-lasting immunity. *Measles* - The measles virus (Rubeola) is a **Paramyxovirus** and is known for its genetic stability. - Due to its lack of significant antigenic variation, vaccination provides **lifelong immunity**, and herd immunity can be achieved. *Mumps* - The mumps virus, also a **Paramyxovirus**, is relatively genetically stable. - It does not undergo antigenic drift or shift to the extent seen in influenza, making the **MMR vaccine** effective for long-term protection.

Q: All are transmitted by blood except -

Epstein-Barr virus. **Epstein-Barr virus** - While Epstein-Barr virus can be detected in blood, its primary mode of transmission is through **saliva** (e.g., kissing, sharing utensils), leading to infectious mononucleosis. - **Blood transfusion transmission** of EBV is rare and not considered a major route of spread in otherwise healthy individuals. *Parvovirus B-19* - **Parvovirus B-19** is well-known to be transmitted via **blood products** and can cause transient aplastic crisis, especially in patients with chronic hemolytic anemias. - It can also be transmitted via **respiratory droplets** and vertically from mother to fetus. *Cytomegalovirus* - **Cytomegalovirus (CMV)** is frequently transmitted through **blood transfusions**, especially to immunocompromised patients. - It can also be transmitted through other bodily fluids, organ transplantation, and congenitally. *Hepatitis G* - **Hepatitis G virus (HGV)**, now renamed **GB virus C (GBV-C)**, is primarily transmitted through **blood** and blood products. - It is often found as a co-infection with hepatitis C virus but its pathogenicity remains controversial.

Q: Which is the most common etiologic agent of acute infantile gastroenteritis?

Rotavirus. ***Rotavirus*** - **Rotavirus** is the leading cause of **severe, dehydrating gastroenteritis** in infants and young children worldwide. - It is highly contagious and spreads via the **fecal-oral route**, causing symptoms like **vomiting, watery diarrhea**, and fever. *Adenovirus* - While adenoviruses can cause gastroenteritis, they are responsible for a **smaller percentage** of cases compared to rotavirus. - Adenovirus infections tend to cause **milder symptoms** and less severe dehydration. *Norwalk virus* - **Norwalk virus**, now classified as **Norovirus**, is a common cause of **gastroenteritis in all age groups**, including children. - However, it is more often associated with **outbreaks in older children and adults**, and rotavirus remains the primary cause in infants. *E. coli* - **Escherichia coli (E. coli)** can cause various forms of gastroenteritis, particularly **enterotoxigenic E. coli (ETEC)** and **enterohemorrhagic E. coli (EHEC)**. - While significant, E. coli is not the **most common overall etiologic agent** for acute infantile gastroenteritis compared to rotavirus.

Q: Which of the following is associated with nasopharyngeal cancer?

Epstein-Barr Virus (EBV). ***Epstein-Barr Virus (EBV)*** - **Epstein-Barr Virus** is strongly and consistently associated with the development of **nasopharyngeal carcinoma (NPC)**, particularly the undifferentiated type. - EBV DNA is often detected in NPC tumor cells, and the virus plays a significant role in **tumorigenesis**. *Herpes Simplex Virus 1 (HSV-1)* - **HSV-1** is primarily associated with **oral herpes** (cold sores) and occasionally **genital herpes**, but not nasopharyngeal cancer. - While it establishes latency in neurons, there is no direct causal link between HSV-1 infection and NPC. *Herpes Simplex Virus 2 (HSV-2)* - **HSV-2** is the main cause of **genital herpes** and is transmitted sexually, but it is not associated with nasopharyngeal cancer. - It establishes latency in sacral ganglia, and its oncogenic potential is primarily linked to cervical cancer in conjunction with HPV, not NPC. *Varicella-Zoster Virus (VZV)* - **VZV** causes **chickenpox** (varicella) in children and **shingles** (herpes zoster) in adults, but it is not linked to nasopharyngeal cancer. - VZV establishes latency in sensory ganglia and reactivates to cause neurological and dermatological symptoms.

Question 1

Shingles is caused by infection with:

Accepted Answer

Varicella zoster virus

Answer

Epstein-Barr virus

Answer

Human papilloma virus

Answer

Herpes simplex virus

Question 2

Which is the most common mode of transmission of HSV-1?

Accepted Answer

Saliva

Answer

Placental transmission

Answer

Sexual transmission

Answer

Blood

Question 3

Influenza pandemics are most commonly caused by-

Accepted Answer

Influenza-A

Answer

Influenza-C

Answer

Influenza-D

Answer

Influenza-B

Question 4

Which of the following statements about Lambda phage is true:

Accepted Answer

Lysogenic form incorporates with host DNA and remains dormant

Answer

Causes mad cow disease

Answer

Lytic and lysogenic interconversion cannot occur

Answer

Lytic form incorporates within host DNA and multiplies causing rupture of cell membrane

Question 5

An 8-year-old boy presented with swelling on both sides of the face, below the ears of 4 days duration. It first started on the left side and then 3 days later on the right side. Cause for the disease will be

Accepted Answer

Paramyxovirus

Answer

Herpes simplex virus

Answer

Cytomegalo virus

Answer

Hepatitis c virus

Question 6

Dangerous type of Herpes virus -

Accepted Answer

Herpes virus simiae

Answer

Cytomegalovirus

Answer

Epstein Barr virus

Answer

Herpes simplex-2

Question 7

Antigenic shift and drift occur in

Accepted Answer

Influenza

Answer

Rubella

Answer

Measles

Answer

Mumps

Question 8

All are transmitted by blood except -

Accepted Answer

Epstein-Barr virus

Answer

Parvovirus B-19

Answer

Cytomegalovirus

Answer

Hepatitis G

Question 9

Which is the most common etiologic agent of acute infantile gastroenteritis?

Accepted Answer

Rotavirus

Answer

Adenovirus

Answer

Norwalk virus

Answer

E. coli

Question 10

Which of the following is associated with nasopharyngeal cancer?

Accepted Answer

Epstein-Barr Virus (EBV)

Answer

Herpes Simplex Virus 1 (HSV-1)

Answer

Herpes Simplex Virus 2 (HSV-2)

Answer

Varicella-Zoster Virus (VZV)

Virology — MCQs

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