Virology Practice Questions

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: 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: Which of the following sexually transmitted infections is caused by a retrovirus?

Human Immunodeficiency Virus (HIV). ***Human Immunodeficiency Virus (HIV)*** - HIV is a **retrovirus** characterized by its use of the enzyme **reverse transcriptase** to convert its RNA genome into DNA. - This viral DNA then integrates into the host cell's genome, leading to a persistent infection and eventual immune system compromise. *Human Papillomavirus (HPV)* - HPV is a **DNA virus** responsible for causing warts and is associated with various cancers, particularly cervical cancer. - It replicates within the nucleus of host cells without utilizing reverse transcriptase. *Hepatitis B Virus (HBV)* - While HBV has a complex replication cycle involving reverse transcription, it is classified as a **hepadnavirus**, not a retrovirus. - Its genome is partially double-stranded DNA, and reverse transcription is used to produce DNA from an RNA intermediate during replication. *Herpes Simplex Virus (HSV)* - HSV is a **DNA virus** belonging to the Herpesviridae family, known for causing oral and genital lesions. - It replicates its DNA genome directly within the host cell nucleus and does not involve reverse transcriptase.

Q: Molluscum contagiosum virus belongs to?

Poxviruses. ***Poxviruses*** - Molluscum contagiosum virus (MCV) is a **DNA virus** belonging to the **Poxviridae family**, genus Molluscipoxvirus. - Poxviruses are among the **largest and most complex viruses**, with a characteristic **brick-shaped or ovoid morphology**. - MCV causes **cutaneous lesions** characterized by smooth, pearly, dome-shaped papules with central umbilication. - Unlike other poxviruses, MCV replicates exclusively in the **cytoplasm** and causes a benign, self-limiting skin infection. *Herpesviruses* - Herpesviruses are also **DNA viruses** (e.g., HSV, VZV, EBV) but belong to the Herpesviridae family. - They are characterized by their ability to establish **lifelong latency** in neurons or lymphocytes. - They have an **icosahedral capsid** with an envelope, distinct from the brick-shaped morphology of poxviruses. - They typically cause vesicular lesions, not the umbilicated papules seen with MCV. *Picornaviruses* - Picornaviruses are **small, non-enveloped RNA viruses** (e.g., poliovirus, coxsackievirus, enteroviruses). - Their name reflects their small size ("pico" = small) and RNA genome. - Their genetic material is **positive-sense single-stranded RNA**, fundamentally different from the DNA genome of MCV. - They cause diverse infections including poliomyelitis, hand-foot-and-mouth disease, and the common cold. *Adenovirus* - Adenoviruses are **non-enveloped, double-stranded DNA viruses** with an **icosahedral capsid**. - They commonly cause respiratory infections, conjunctivitis, and gastroenteritis. - While they are DNA viruses, their morphology, replication strategy, and disease manifestations are distinct from the cutaneous lesions caused by MCV.

Q: Among the following, which is the smallest virus?

Parvovirus. ***Parvovirus*** - **Parvoviruses** are among the smallest viruses, typically measuring around **18-26 nanometers** in diameter. - They are unique in having a **single-stranded DNA genome**. *Herpes virus* - **Herpesviruses** are relatively large, **double-stranded DNA viruses** with diameters ranging from **150-200 nanometers**. - They are known for establishing **latent infections** in the host. *Adenovirus* - **Adenoviruses** are medium-sized, **non-enveloped, icosahedral viruses** with **double-stranded DNA genomes**, typically 70-90 nanometers in diameter. - They are a common cause of respiratory, gastrointestinal, and ocular infections. *Poxvirus* - **Poxviruses** are exceptionally large and complex viruses, measuring approximately **200-400 nanometers** in length, and are visible under a light microscope. - They have a unique **brick-shaped morphology** and a **double-stranded DNA genome**.

Q: Which paramyxovirus does not have hemagglutinin and neuraminidase but has a membrane fusion protein?

RSV. ***RSV*** - **Respiratory Syncytial Virus (RSV)** is unique among paramyxoviruses because it lacks both **hemagglutinin (H)** and **neuraminidase (N)** glycoproteins. - Its pathogenicity relies on its **fusion (F) protein**, which causes respiratory epithelial cells to fuse, forming **syncytia**. *Measles* - The **measles virus** (Morbillivirus) possesses both **hemagglutinin (H)** and **fusion (F)** proteins, but it lacks neuraminidase. - The **H protein** is responsible for viral attachment, while the **F protein** mediates membrane fusion and syncytia formation. *Parainfluenza* - **Parainfluenza viruses** all possess both **hemagglutinin-neuraminidase (HN)** protein and **fusion (F)** protein. - The **HN protein** is responsible for both receptor binding and cleaving sialic acid residues, aiding in viral release. *Mumps* - The **mumps virus** also belongs to the paramyxovirus family and possesses both a **hemagglutinin-neuraminidase (HN)** protein and a **fusion (F)** protein. - These proteins are crucial for its ability to attach to host cells and mediate viral entry.

Q: What is the cause of Herpes Zoster?

Reactivation of latent infection of VZV. ***Reactivation of latent infection of VZV*** - Herpes Zoster, commonly known as **shingles**, occurs when the **varicella-zoster virus (VZV)**, which lies dormant in sensory ganglia after a primary chickenpox infection, reactivates. - This **reactivation** typically happens due to a decline in cellular immunity, often associated with age, stress, or immunosuppression. *Primary infection with VZV* - A primary infection with VZV causes **chickenpox** (varicella), not herpes zoster. - After chickenpox resolves, the virus establishes a **latent infection** in the dorsal root ganglia. *Recurrent infection with VZV* - While VZV can cause recurrent episodes, the term "recurrent infection" usually implies a new exposure or reinfection, which is not the typical mechanism for shingles. - Shingles is specifically due to the **awakening of the existing latent virus**, not a new external infection. *Multiple infection with VZV* - "Multiple infection" implies several separate instances of exposure and infection, which is not the underlying cause of Herpes Zoster. - Herpes Zoster arises from the **viral genome already present** within the host's nerve cells.

Q: Most common pox virus infection in humans is?

Molluscum contagiosum. ***Molluscum contagiosum*** - This is a common, **benign viral skin infection** that causes small, pearl-like papules with central umbilication. - It is highly prevalent, especially in children, sexually active adults, and immunocompromised individuals, making it the most frequent human poxvirus infection. *Smallpox* - While historically significant, **smallpox** was eradicated globally in 1980 through widespread vaccination efforts. - It is no longer a naturally occurring infection in humans. *Monkeypox* - **Monkeypox** is a zoonotic disease that has recently seen outbreaks, but it is not as widespread or common as molluscum contagiosum. - It is characterized by fever, lymphadenopathy, and a distinctive rash, often with a more severe clinical presentation than molluscum. *Cowpox* - **Cowpox** is a rare disease primarily found in animals (e.g., cats, rodents) and occasionally transmitted to humans, typically through contact with infected animals. - Human infections are sporadic and far less common than molluscum contagiosum.

Question 1

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 2

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 3

Which of the following is Hepadnavirus?

Accepted Answer

HBV

Answer

HAV

Answer

HCV

Answer

HDV

Question 4

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 5

Which of the following sexually transmitted infections is caused by a retrovirus?

Accepted Answer

Human Immunodeficiency Virus (HIV)

Answer

Hepatitis B Virus (HBV)

Answer

Human Papillomavirus (HPV)

Answer

Herpes Simplex Virus (HSV)

Question 6

Molluscum contagiosum virus belongs to?

Accepted Answer

Poxviruses

Answer

Herpesviruses

Answer

Picornaviruses

Answer

Adenovirus

Question 7

Among the following, which is the smallest virus?

Accepted Answer

Parvovirus

Answer

Herpes virus

Answer

Adenovirus

Answer

Poxvirus

Question 8

Which paramyxovirus does not have hemagglutinin and neuraminidase but has a membrane fusion protein?

Accepted Answer

RSV

Answer

Measles

Answer

Parainfluenza

Answer

Mumps

Question 9

What is the cause of Herpes Zoster?

Accepted Answer

Reactivation of latent infection of VZV

Answer

Primary infection with VZV

Answer

Recurrent infection with VZV

Answer

Multiple infection with VZV

Question 10

Most common pox virus infection in humans is?

Accepted Answer

Molluscum contagiosum

Answer

Smallpox

Answer

Monkeypox

Answer

Cowpox

Virology — MCQs

Virology — MCQs

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