Virology Practice Questions

Q: What is the Australian antigen for hepatitis B?

HBsAg. ***HBsAg*** - **HBsAg** stands for **Hepatitis B surface antigen**, which was originally discovered by Baruch Blumberg in 1965 and was initially called the **Australia antigen** due to its discovery in the serum of an Australian aboriginal. - Its presence indicates an **active hepatitis B infection**, either acute or chronic. *HBeAg* - **HBeAg** (Hepatitis B e-antigen) is a marker of **viral replication** and **infectivity**. - It is distinct from HBsAg and indicates a high level of **transmissibility** of the virus. *HBDAg* - **HBDAg** is not a standard or recognized antigen for hepatitis B. - The correct antigen for hepatitis D is **HDAg** (Hepatitis D antigen), which is only found in individuals co-infected with hepatitis D virus and hepatitis B virus. *HBV DNA* - **HBV DNA** refers to the viral genetic material of the hepatitis B virus. - While its presence indicates active viral replication and is used to monitor **viral load**, it is not an antigen but rather the **viral genome** itself.

Q: Acute Hemorrhagic Conjunctivitis is primarily caused by which type of Enterovirus?

Enterovirus type 70. ***Enterovirus type 70*** - **Enterovirus type 70** is the most common cause of **Acute Hemorrhagic Conjunctivitis (AHC)**, particularly in epidemic outbreaks. - AHC presents with rapid onset of **ocular pain**, **redness**, **swelling**, and **subconjunctival hemorrhages**. *Enterovirus type 68* - **Enterovirus D68 (EV-D68)** is primarily known for causing **respiratory illnesses**, ranging from mild to severe, and is associated with acute flaccid myelitis. - While it can cause respiratory symptoms, it is not a primary cause of **Acute Hemorrhagic Conjunctivitis**. *Enterovirus type 69* - **Enterovirus type 69** is a rare serotype and is not typically associated with specific human diseases or large-scale outbreaks. - Unlike EV70, it is not recognized as a significant cause of **conjunctivitis**. *Enterovirus type 71* - **Enterovirus A71 (EV-A71)** is a common cause of **hand, foot, and mouth disease (HFMD)**, especially in children, and can also lead to severe neurological complications. - While it causes various infections, it is not the primary cause of **hemorrhagic conjunctivitis**.

Q: Rubella virus belongs to which family?

Togavirus. ***Togavirus*** - The **Rubella virus** is categorized under the family **Togaviridae**, specifically within the genus *Rubivirus*. - This classification is based on its genetic structure, being an **enveloped, positive-sense, single-stranded RNA virus**. *Rheovirus* - **Reoviruses** are characterized by a **double-stranded segmented RNA genome** and are typically non-enveloped. - This contrasts with Rubella's single-stranded, non-segmented RNA and enveloped structure. *Picornavirus* - **Picornaviruses** are a family of **non-enveloped, positive-sense, single-stranded RNA viruses** that are structurally different from Rubella. - Examples include species like **poliovirus** and **rhinovirus**, which do not share the distinct biological properties of Rubella. *Orthomyxovirus* - **Orthomyxoviruses** are a family of **enveloped, negative-sense, segmented RNA viruses**, which includes influenza viruses. - Their genomic organization and replication strategy are fundamentally different from those of the Rubella virus.

Q: Genital warts are caused by which virus?

Human Papillomavirus (HPV). ***Human Papillomavirus (HPV)*** - **HPV** is the causative agent of **genital warts**, which are benign epithelial growths. - Specific low-risk HPV types, primarily **HPV types 6 and 11**, are responsible for the vast majority of genital wart cases. *Herpes simplex virus (HSV)* - **HSV** causes **genital herpes**, characterized by painful blisters and ulcers, not warts. - There are two main types: **HSV-1** (often oral herpes) and **HSV-2** (primarily genital herpes). *Cytomegalovirus (CMV)* - **CMV** is a common virus that usually causes **asymptomatic infection** in healthy individuals but can lead to severe disease in immunocompromised patients or neonates. - It is not associated with the formation of genital warts. *Varicella zoster virus (VZV)* - **VZV** is responsible for **chickenpox** (varicella) in primary infection and **shingles** (herpes zoster) during reactivation. - It does not cause genital warts.

Q: What is a potential outcome of the integration of a viral genome into a host cell chromosome?

All of the options. ***All of the options*** - The insertion of a viral genome, known as a **provirus**, into the host chromosome can lead to a variety of sustained and complex interactions. - This integration can cause **long-term changes** in cell behavior, including altered gene expression and cell cycle regulation, which may manifest as any of the specified outcomes. *Malignancy* - Viral integration can interrupt or activate host genes, such as **oncogenes** or **tumor suppressor genes**, leading to uncontrolled cell proliferation and potential tumor formation. - An example is **human papillomavirus (HPV)** integrating into host cells, increasing the risk of cervical cancer. *Altered growth* - Integration can change the cell's normal growth patterns, either by promoting excessive division or by causing cell cycle arrest, impacting tissue development and function. - This can be due to the insertion of viral promoters or enhancers near growth-regulating genes. *Latency* - The integrated viral genome can remain dormant within the host chromosome without producing new viral particles for extended periods, a state known as **latency**. - During latency, the virus can be reactivated later to cause a productive infection, as seen with **herpesviruses**.

Q: HTLV-1 can be transmitted by -

Blood transfusion. ***Blood transfusion*** - **HTLV-1 (Human T-lymphotropic virus type 1)** can be effectively transmitted through **blood products** and is a significant concern for blood safety. - **Major transmission routes of HTLV-1 include**: blood transfusion, breastfeeding (mother-to-child, most common in endemic areas), sexual contact, and sharing contaminated needles. - Screening of blood donors for HTLV-1/2 antibodies is crucial in endemic areas (Japan, Caribbean, parts of Africa and South America) to prevent transfusion-associated transmission. - This mode of transmission has been significantly reduced in countries with mandatory donor screening programs. *Droplet inhalation* - **HTLV-1** is **not transmitted via respiratory droplets** or aerosols, unlike viruses such as influenza or SARS-CoV-2. - Transmission requires direct contact with **infected cells** (primarily CD4+ T lymphocytes) or bodily fluids containing infected cells. - HTLV-1 is a cell-associated virus, not present free in respiratory secretions. *Contaminated water* - **HTLV-1** is a **blood-borne and sexually transmitted retrovirus** and is not transmitted through contaminated water. - The virus cannot survive in water and requires cell-to-cell contact or cell-containing fluids for transmission. - Waterborne diseases are caused by pathogens that can survive in aquatic environments, which does not apply to HTLV-1. *Animal bite* - **HTLV-1** is a **human-specific retrovirus** with no animal reservoir; it is not transmitted through animal bites. - Unlike zoonotic viruses (rabies, certain arboviruses), HTLV-1 transmission is strictly human-to-human. - The virus specifically infects human CD4+ T cells and does not have vectors or animal hosts.

Q: HIV envelope is formed by:

Both. ***Both (Correct Answer)*** - The HIV envelope is a **composite structure** derived from both host and viral components - The **lipid bilayer** is acquired from the **host cell membrane** during viral budding - **Viral glycoproteins (gp120 and gp41)** encoded by the viral genome are inserted into this host-derived membrane - This makes the envelope a true hybrid structure essential for viral infectivity *Host cell (Incomplete)* - While the **lipid bilayer** of the envelope comes from the host cell membrane during budding, this alone does not form a functional envelope - The host cell provides the membrane scaffold but lacks the viral glycoproteins necessary for receptor binding and cell entry - Without viral proteins, the envelope cannot mediate infection *Virus (Incomplete)* - The virus encodes essential **envelope glycoproteins** (gp120 for receptor binding, gp41 for membrane fusion) - However, the virus does **not synthesize the lipid bilayer** itself - The viral genome lacks genes for lipid synthesis; the membrane must be acquired from the host *None of the options* - This is incorrect as the HIV envelope clearly requires contributions from **both** the host cell (lipid membrane) and the virus (glycoproteins)

Q: Which of the following statements about paramyxoviruses is false?

Are DNA viruses. ***Are DNA viruses*** - Paramyxoviruses are characterized by their **single-stranded, negative-sense RNA genome**, not DNA. - Their replication and transcription processes occur in the cytoplasm, which is typical for RNA viruses. *Belong to the family Paramyxoviridae* - This statement is correct; paramyxoviruses are indeed classified under the **family Paramyxoviridae**. - This family includes important human pathogens like measles, mumps, and respiratory syncytial virus (RSV). *Have linear nucleic acid* - This statement is correct as paramyxoviruses possess a **linear, non-segmented RNA genome**. - The linear nature differentiates them from viruses with segmented genomes, such as influenza viruses. *Are RNA viruses* - This statement is correct; paramyxoviruses are characterized by their **RNA genome**. - Specifically, they are **negative-sense, single-stranded RNA viruses**.

Q: Which of the following viruses is a member of the Herpesviridae family?

Herpes Simplex Virus. ***Herpes Simplex Virus*** - **Herpes Simplex Virus (HSV)** is the type species of the *Herpesviridae* family, which includes other common human pathogens such as **cytomegalovirus** and **Epstein-Barr virus**. - Members of this family are characterized by a **double-stranded DNA genome**, an icosahedral capsid, and an envelope, and they typically cause **latent infections**. *Variola* - **Variola virus** is a member of the *Poxviridae* family, known for causing **smallpox**, a historically devastating disease. - Unlike herpesviruses, poxviruses are **large and complex DNA viruses** that replicate entirely in the cytoplasm of infected cells. *Adenovirus* - **Adenovirus** belongs to the *Adenoviridae* family and is a **non-enveloped DNA virus** known for causing a variety of conditions, including respiratory infections and conjunctivitis. - Its structure and replication cycle differ significantly from the enveloped *Herpesviridae*. *HPV* - **HPV (Human Papillomavirus)** is a member of the *Papillomaviridae* family, which are small **non-enveloped DNA viruses** associated with warts and certain cancers. - It is distinct from herpesviruses in its genomic organization, capsid structure, and disease manifestations.

Q: Which HIV virus is associated with a higher transmission rate and virulence?

HIV-1. ***HIV-1*** - **HIV-1** is responsible for the vast majority of HIV infections worldwide and is known for its **higher virulence** and more rapid progression to AIDS. - It also has a **higher transmission rate** compared to HIV-2, contributing to its global prevalence. *HIV-2* - **HIV-2** is less virulent and has a **slower progression** to AIDS compared to HIV-1. - Its transmission rate is **lower** than HIV-1, and it is primarily concentrated in West Africa. *Both have similar risks* - This statement is incorrect because **HIV-1 and HIV-2 differ significantly** in their transmission rates, virulence, and disease progression. - **HIV-1** poses a much greater global health burden due to its higher infectivity and pathology. *It depends on individual factors* - While individual factors can influence disease progression, the intrinsic characteristics of **HIV-1** and **HIV-2** (such as transmissibility and virulence) are distinct and not solely dependent on the host. - The inherent biological differences between the two viruses are the primary determinants of their differential impact.

Question 1

What is the Australian antigen for hepatitis B?

Accepted Answer

HBsAg

Answer

HBeAg

Answer

HBDAg

Answer

HBV DNA

Question 2

Acute Hemorrhagic Conjunctivitis is primarily caused by which type of Enterovirus?

Accepted Answer

Enterovirus type 70

Answer

Enterovirus type 68

Answer

Enterovirus type 69

Answer

Enterovirus type 71

Question 3

Rubella virus belongs to which family?

Accepted Answer

Togavirus

Answer

Orthomyxovirus

Answer

Rheovirus

Answer

Picornavirus

Question 4

Genital warts are caused by which virus?

Accepted Answer

Human Papillomavirus (HPV)

Answer

Cytomegalovirus (CMV)

Answer

Herpes simplex virus (HSV)

Answer

Varicella zoster virus (VZV)

Question 5

What is a potential outcome of the integration of a viral genome into a host cell chromosome?

Accepted Answer

All of the options

Answer

Altered growth

Answer

Malignancy

Answer

Latency

Question 6

HTLV-1 can be transmitted by -

Accepted Answer

Blood transfusion

Answer

Droplet inhalation

Answer

Contaminated water

Answer

Animal bite

Question 7

HIV envelope is formed by:

Accepted Answer

Both

Answer

Host cell

Answer

Virus

Answer

None of the options

Question 8

Which of the following statements about paramyxoviruses is false?

Accepted Answer

Are DNA viruses

Answer

Belong to the family Paramyxoviridae

Answer

Are RNA viruses

Answer

Have linear nucleic acid

Question 9

Which of the following viruses is a member of the Herpesviridae family?

Accepted Answer

Herpes Simplex Virus

Answer

Variola

Answer

Adenovirus

Answer

HPV

Question 10

Which HIV virus is associated with a higher transmission rate and virulence?

Accepted Answer

HIV-1

Answer

Both have similar risks

Answer

It depends on individual factors

Answer

HIV-2

Virology — MCQs

Virology — MCQs

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