Virology Practice Questions

Q: What is the primary mechanism by which the influenza virus changes antigenically over time?

Antigenic drift. ***Antigenic drift*** - This involves **gradual accumulation of point mutations** in the genes encoding for **hemagglutinin (HA)** and **neuraminidase (NA)** glycoproteins - These **minor changes** allow the virus to **evade immune recognition** partially, necessitating **frequent updates to influenza vaccines** - Occurs **continuously** in both influenza A and B viruses - Responsible for **seasonal epidemics** of influenza *Antigenic shift* - This involves **major changes** due to **reassortment of gene segments** between different influenza virus strains - Results in a **novel subtype** with different HA and/or NA proteins - Can lead to **pandemics** when human population has no immunity - This is a **sudden, major change** rather than the gradual change described in the question *Reassortment* - This is the **mechanism underlying antigenic shift**, where gene segments from different strains exchange during co-infection - While related to influenza variation, the question asks for the **primary ongoing mechanism**, which is antigenic drift - Reassortment is less frequent but creates more dramatic changes *Recombination* - This involves **exchange of genetic material** between viral genomes - **Uncommon in influenza viruses** due to their segmented genome structure - Reassortment, not recombination, is the dominant mechanism for genetic exchange in influenza

Q: A patient presents with painful blisters around the angle of the mouth. What is the most likely pathogen responsible for this condition?

Herpes Simplex Virus. ***Herpes Simplex Virus*** - The image shows a cluster of **small, painful vesicles** on an erythematous base around the mouth, characteristic of **herpes labialis** or cold sores. - HSV-1 is the primary cause of oral herpes, which typically presents with these recurrent painful blister outbreaks. *Coxsackievirus* - Coxsackievirus typically causes **Hand, Foot, and Mouth Disease**, characterized by oral lesions (herpangina) and a rash on the hands and feet. - The painful blisters are usually in the **posterior oral cavity** (soft palate, tonsillar pillars) and are not typically perioral in the depicted clustered vesicular pattern. *Varicella-Zoster Virus* - VZV causes **chickenpox** (widespread vesicular rash) and **shingles** (painful, dermatomal vesicular rash). - While it causes vesicles, they would present as either widespread and generalized or in a unilateral, **dermatomal distribution**, which is not consistent with the perioral presentation shown. *Epstein-Barr Virus* - EBV is primarily known for causing **infectious mononucleosis**, which can lead to fatigue, fever, and lymphadenopathy, and sometimes oral manifestations like palatal petechiae or oral hairy leukoplakia. - It does not typically cause the **painful vesicular lesions** around the mouth as depicted.

Q: Which disease is caused by Coxsackievirus A16?

Hand-foot-mouth disease. ***Hand-foot-mouth disease*** - **Coxsackievirus A16** is one of the most common causes of **hand-foot-mouth disease (HFMD)**, along with Enterovirus 71. - HFMD typically presents with **fever**, **painful vesicles and ulcers in the mouth** (on the tongue, gums, and inside of cheeks), and a **vesicular rash on the palms, soles, and sometimes buttocks**. - It primarily affects young children and is highly contagious. *Yellow fever* - Yellow fever is caused by the **yellow fever virus**, a **flavivirus**, which is transmitted by mosquitoes. - It leads to symptoms like fever, jaundice, and hemorrhage, distinctly different from Coxsackievirus A16 infections. *Rocky Mountain spotted fever* - This disease is caused by the bacterium **Rickettsia rickettsii** and is transmitted by ticks. - It presents with fever, headache, and a characteristic rash that often starts on the ankles and wrists. *Encephalomyocarditis* - While Coxsackieviruses (particularly Coxsackievirus B serotypes) can cause myocarditis and encephalitis, **encephalomyocarditis virus (EMCV)** is a distinct cardiovirus within the Picornaviridae family. - Coxsackievirus A16 is not typically associated with encephalomyocarditis as its primary manifestation.

Q: Capsid of viral structure is:

Protein coat around nucleic acid. ***Protein coat around nucleic acid*** - The **capsid** is a protective protein shell that encloses the viral **genetic material** (either **DNA or RNA**). - It plays a crucial role in protecting the viral genome from nucleases and aids in attaching the **virion** to host cells. *Extracellular infectious particle* - An **extracellular infectious particle** refers to the entire **virion**, which includes the capsid and its enclosed nucleic acid, and sometimes an envelope. - The **capsid** is only one component of the **virion**, not the entire particle itself. *Envelope around a virus* - The **envelope** is an outer **lipid bilayer** derived from the host cell membrane that surrounds some, but not all, viruses. - The **capsid** is located *inside* the envelope in enveloped viruses, or forms the outermost layer in non-enveloped viruses. *None of the above* - This option is incorrect because **"Protein coat around nucleic acid"** accurately defines the **capsid**.

Q: Which of the following conditions is NOT typically caused by Respiratory Syncytial Virus (RSV)?

Severe lung condition (ARDS).. ***Severe lung condition (ARDS)*** - While RSV can cause severe respiratory illness, **Acute Respiratory Distress Syndrome (ARDS)** is a less typical direct consequence of RSV infection, especially in healthy individuals. - ARDS is characterized by **widespread inflammation** in the lungs leading to fluid accumulation and severe oxygenation impairment, which is more commonly associated with septic shock, pneumonia from severe bacterial or other viral infections, or aspiration. *Upper respiratory tract infection in children (coryza)* - **Coryza** (common cold symptoms like runny nose, sneezing, and watery eyes) is a very common initial presentation of **RSV infection**, particularly in infants and young children. - RSV frequently causes **upper respiratory symptoms** before progressing to lower respiratory tract involvement in some cases. *Lower respiratory tract infection (bronchitis)* - RSV commonly causes **bronchitis** (inflammation of the bronchi) in children and can lead to **bronchiolitis** (inflammation of the smaller bronchioles), with RSV being the **leading cause of bronchiolitis** in infants under 2 years of age. - RSV can also cause **pneumonia**, making it an important cause of lower respiratory tract infections, especially in vulnerable populations like infants, elderly, and immunocompromised individuals. *Mild cold-like symptoms* - In older children and adults, RSV infection often manifests as **mild, self-limiting cold-like symptoms**, similar to a common cold. - These symptoms typically include a stuffy nose, sore throat, cough, and low-grade fever, which resolve within a week or two.

Q: Ebola virus belongs to?

Filoviridae. ***Filoviridae*** - The **Ebola virus** is a member of the family **Filoviridae**, which includes highly pathogenic viruses known for causing severe hemorrhagic fevers. - Viruses in this family typically have a **filamentous** or thread-like morphology, which is how they get their name ("filo" means thread-like). ***Picornaviridae*** - This family includes viruses like *poliovirus* and *rhinoviruses*, which are generally known for causing respiratory or gastrointestinal illnesses, not hemorrhagic fever. - Picornaviruses are characterized by being very small, non-enveloped RNA viruses. ***Togaviridae*** - This family includes viruses such as *rubella virus* and *alphaviruses* (e.g., Eastern equine encephalitis virus), which are often transmitted by arthropods and cause conditions like rash, arthritis, or encephalitis. - Togaviruses are enveloped RNA viruses with a single-stranded, positive-sense RNA genome. ***Flaviviridae*** - This family includes viruses like *dengue virus*, *Zika virus*, and *yellow fever virus*, which are typically transmitted by mosquitoes or ticks and can cause hemorrhagic manifestations or neurological symptoms. - Flaviviruses are enveloped RNA viruses with a single-stranded, positive-sense RNA genome, but they do not cause Ebola-like hemorrhagic fever.

Q: Which is the most common influenza virus type causing disease in humans?

Type A. ***Type A*** - **Influenza A virus** is responsible for the majority of human influenza cases and is the only type known to cause **pandemics**. - Its ability to undergo **antigenic shift** results in new viral subtypes that can evade existing immunity, leading to widespread outbreaks. *Type B* - **Influenza B virus** causes regional epidemics, but its genetic variability is less pronounced than Type A, meaning it does not typically cause pandemics. - While it can cause significant illness and fatalities, especially in young children and the elderly, it is generally less common than influenza A. *Type C* - **Influenza C virus** is generally associated with very mild respiratory illnesses and is not thought to cause epidemics or pandemics. - Infections are usually asymptomatic or cause only minor cold-like symptoms. *Type D* - **Influenza D virus** primarily affects pigs and cattle and is not known to cause disease in humans. - It is distinct from human influenza viruses and does not contribute to human influenza seasonal outbreaks.

Q: What is the most clinically significant common characteristic of rotavirus and Norwalk virus?

Both are causes of viral gastroenteritis. ***Both are causes of viral gastroenteritis*** - **Rotavirus** and **Norwalk virus** (now typically referred to as norovirus) are the leading causes of acute viral gastroenteritis worldwide, affecting both children and adults. - This condition is characterized by symptoms such as **diarrhea**, **vomiting**, **abdominal pain**, and fever. *Both are RNA viruses* - While **Rotavirus is an RNA virus**, specifically a double-stranded RNA virus, the Norwalk virus (norovirus) is also an RNA virus, but it's a single-stranded RNA virus. Therefore, this statement is factually correct, but less specific as a "common characteristic" of their clinical relevance. - The shared clinical outcome of causing gastroenteritis is a more direct and common characteristic for comparing these pathogens in a medical context. *Both are transmitted via contaminated food or water* - While both viruses can be transmitted through **contaminated food and water** (fecal-oral route), this is not their exclusive mode of transmission. - **Norovirus** is highly contagious and often spreads person-to-person or via contaminated surfaces, and **rotavirus** can also spread through direct contact in addition to contaminated sources. *Both can cause outbreaks in closed communities* - While both viruses can indeed cause **outbreaks in closed communities** like cruise ships, daycares, and nursing homes, this is a consequence of their highly contagious nature and fecal-oral transmission, rather than their most fundamental shared characteristic. - The primary medical characteristic they share is their role as causative agents of **viral gastroenteritis**.

Q: Which of the following is Hepadnavirus?

HBV. ***HBV*** - **HBV (Hepatitis B Virus)** is the prototypical member of the Hepadnaviridae family. - Hepadnaviruses are unique in that they are **DNA viruses** that replicate through an **RNA intermediate** using reverse transcriptase. *HAV* - **HAV (Hepatitis A Virus)** belongs to the Picornaviridae family, which are **small, non-enveloped RNA viruses**. - It is transmitted via the **fecal-oral route** and causes acute hepatitis. *HCV* - **HCV (Hepatitis C Virus)** is a member of the Flaviviridae family, characterized by being an **enveloped, positive-sense single-stranded RNA virus**. - It primarily causes **chronic hepatitis** and is transmitted parenterally. *HDV* - **HDV (Hepatitis D Virus)** is a **defective RNA virus** that requires co-infection with HBV for replication. - It is classified in the genus **Deltavirus** and is a **satellite virus** of HBV, not a member of Hepadnaviridae.

Q: Hand foot mouth disease is caused by ?

Coxsackievirus A. ***Coxsackievirus A*** - Hand-foot-and-mouth disease (HFMD) is most commonly caused by **Coxsackievirus A16** and occasionally other **Coxsackievirus A serotypes** (especially **Enterovirus A71** in Asia). - This virus belongs to the **Enterovirus genus** and is responsible for the characteristic vesicular rash on hands, feet, and mouth. *Enterovirus 70* - **Enterovirus 70** is primarily associated with **acute hemorrhagic conjunctivitis** and, less commonly, **acute flaccid paralysis**. - It is not the causative agent for Hand-Foot-and-Mouth Disease. *Coxsackievirus B* - **Coxsackievirus B** serotypes are known for causing illnesses like **pleurodynia**, **myocarditis**, and **pericarditis**. - While also an enterovirus, it is not the primary cause of Hand-Foot-and-Mouth Disease. *Enterovirus* - **Enterovirus** is a broad genus of viruses, encompassing **Coxsackieviruses**, **echoviruses**, and **polioviruses**. - While Coxsackievirus A is an enterovirus, simply stating "Enterovirus" is too general and less specific than the correct answer.

Question 1

What is the primary mechanism by which the influenza virus changes antigenically over time?

Accepted Answer

Antigenic drift

Answer

Recombination

Answer

Reassortment

Answer

Antigenic shift

Question 2

A patient presents with painful blisters around the angle of the mouth. What is the most likely pathogen responsible for this condition?

Accepted Answer

Herpes Simplex Virus

Answer

Coxsackievirus

Answer

Varicella-Zoster Virus

Answer

Epstein-Barr Virus

Question 3

Which disease is caused by Coxsackievirus A16?

Accepted Answer

Hand-foot-mouth disease

Answer

Yellow fever

Answer

Rocky Mountain spotted fever

Answer

Encephalomyocarditis

Question 4

Capsid of viral structure is:

Accepted Answer

Protein coat around nucleic acid

Answer

Extracellular infectious particle

Answer

Envelope around a virus

Answer

None of the above

Question 5

Which of the following conditions is NOT typically caused by Respiratory Syncytial Virus (RSV)?

Accepted Answer

Severe lung condition (ARDS).

Answer

Upper respiratory tract infection in children (coryza).

Answer

Lower respiratory tract infection (bronchitis).

Answer

Mild cold-like symptoms.

Question 6

Ebola virus belongs to?

Accepted Answer

Filoviridae

Answer

Picornaviridae

Answer

Togaviridae

Answer

Flaviviridae

Question 7

Which is the most common influenza virus type causing disease in humans?

Accepted Answer

Type A

Answer

Type B

Answer

Type C

Answer

Type D

Question 8

What is the most clinically significant common characteristic of rotavirus and Norwalk virus?

Accepted Answer

Both are causes of viral gastroenteritis

Answer

Both are RNA viruses

Answer

Both are transmitted via contaminated food or water

Answer

Both can cause outbreaks in closed communities

Question 9

Which of the following is Hepadnavirus?

Accepted Answer

HBV

Answer

HAV

Answer

HCV

Answer

HDV

Question 10

Hand foot mouth disease is caused by ?

Accepted Answer

Coxsackievirus A

Answer

Enterovirus 70

Answer

Coxsackievirus B

Answer

Enterovirus

Virology — MCQs

Virology — MCQs

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