Virology Practice Questions

Q: Which of the following statements about herpes simplex virus (HSV) shedding is MOST accurate?

Asymptomatic shedding accounts for most sexual transmission. ***Asymptomatic shedding accounts for most sexual transmission*** - **Asymptomatic shedding** of HSV is very common and often goes unnoticed, leading to unsuspecting transmission to sexual partners. - Studies show that a significant proportion, often over 70%, of HSV acquisition occurs during contact with an infected partner who is **asymptomatically shedding** the virus. *HSV-1 sheds more frequently than HSV-2 in the genital tract* - While HSV-1 can cause genital herpes, **HSV-2 is the predominant cause of genital herpes** and typically sheds more frequently and for longer durations from the genital tract than HSV-1. - **Recurrent genital HSV-2 outbreaks** are also more common than recurrent genital HSV-1 outbreaks, reflecting the greater propensity for shedding. *Viral shedding occurs only during symptomatic episodes* - This statement is incorrect because **viral shedding frequently occurs in the absence of visible lesions or symptoms**, a phenomenon known as asymptomatic shedding. - Patients can shed the virus before the appearance of lesions (prodrome), during symptomatic periods, and often following resolution of symptoms or in completely **asymptomatic periods**. *Antiviral suppression completely eliminates viral shedding* - Antiviral medications like acyclovir, valacyclovir, and famciclovir can **significantly reduce the frequency and duration of HSV shedding**, both symptomatic and asymptomatic. - However, they do **not completely eliminate viral shedding**, meaning that transmission is still possible even with suppressive therapy.

Q: What is the mechanism behind the increased risk of HIV acquisition in individuals with genital herpes?

HSV disrupts epithelial barrier and recruits CD4+ cells. ***HSV disrupts epithelial barrier and recruits CD4+ cells*** - Genital herpes causes **lesions and ulcerations** in the genital mucosa, which disrupt the integrity of the epithelial barrier, creating portals of entry for HIV. - The inflammatory response to HSV infection leads to the recruitment of **CD4+ T cells** and other HIV target cells to the genital tract, making them readily available for HIV infection. *HSV glycoproteins enhance HIV binding to target cells* - While HSV modifies cellular surfaces, its glycoproteins are not directly known to **enhance HIV binding** to its primary receptors (CD4 and co-receptors) on target cells. - This mechanism is not considered a primary driver of the increased HIV acquisition risk in the context of HSV. *HSV inhibits local innate immune responses* - HSV does have mechanisms to evade host immunity, but its primary impact on HIV acquisition is not through a generalized **inhibition of overall innate immune responses** that would directly increase HIV entry. - Instead, the physical disruption and cellular recruitment are more significant factors. *HSV increases HIV viral load through transactivation* - This mechanism refers more to the potential interaction of HSV with established HIV infection to **replicate more HIV**, not primarily to the initial acquisition of HIV. - While co-infection *can* impact HIV viral replication, it's not the main reason for increased susceptibility to *acquiring* HIV.

Q: A patient is a known case of thalassemia. Which of the following viruses would be responsible for attacking progenitor cells and causing aplastic anemia?

Parvovirus B19. ***Parvovirus B19*** - **Parvovirus B19** specifically targets and replicates in **erythroid progenitor cells** in the bone marrow, leading to a temporary halt in red blood cell production [1]. - In patients with chronic hemolytic anemias like **thalassemia**, who already have increased erythropoietic demands, this can precipitate an **aplastic crisis** or pure red cell aplasia [1], [2]. *CMV (Cytomegalovirus)* - While CMV can affect the bone marrow and lead to myelosuppression, it does not typically cause a direct **aplastic crisis** by targeting erythroid progenitors in the same way as Parvovirus B19. - CMV often presents with a wider range of symptoms including fever, hepatitis, and mononucleosis-like syndrome, and bone marrow suppression is usually multi-lineage or less severe. *EBV (Epstein-Barr Virus)* - EBV is known to cause infectious mononucleosis and can also be associated with some bone marrow disorders, but it does not primarily target **erythroid progenitor cells** to cause an aplastic crisis. - Its main target cells are **B lymphocytes**, and any bone marrow suppression is often secondary to immune dysregulation rather than direct lytic infection of stem cells. *Hepatitis C virus (HCV)* - HCV infection can lead to various hematologic manifestations, including aplastic anemia, but these are typically **immune-mediated** or associated with chronic liver disease and its complications. - HCV does not directly infect and destroy **hematopoietic progenitor cells** in the bone marrow as a primary mechanism of aplastic anemia.

Q: Which viral infection is most likely responsible for triggering this aplastic crisis in the patient?

Parvovirus B19. ***Parvovirus B19*** - **Parvovirus B19** specifically targets and destroys **red blood cell precursors** in the bone marrow, leading to a temporary cessation of erythropoiesis [1]. - In patients with underlying hemolytic anemias (e.g., **sickle cell disease**, **hereditary spherocytosis**), this temporary aplasia can trigger a severe **aplastic crisis** due to their already shortened red blood cell lifespan [2]. *Epstein-Barr Virus (EBV)* - While EBV can cause various hematologic complications, including some myelosuppression, it is not typically associated with triggering acute **aplastic crises** due to direct erythroid precursor destruction [3]. - EBV is primarily known for causing **infectious mononucleosis** and is linked to lymphoproliferative disorders [3]. *Hepatitis B Virus (HBV)* - HBV infection primarily affects the **liver** and is not a common cause of acute **aplastic crisis** by directly targeting bone marrow hematopoietic cells. - Chronic HBV infection can rarely be associated with **aplastic anemia**, but not usually with an acute crisis. *Cytomegalovirus (CMV)* - CMV can cause myelosuppression, especially in **immunocompromised individuals**, and may lead to pancytopenia. - However, CMV does not typically induce the sudden and severe **erythroid aplasia** characteristic of an aplastic crisis in hemolytic anemia patients, as seen with Parvovirus B19 [1].

Q: A pregnant woman, whose niece contracted varicella while living in the same house, tested negative for serum antibodies to varicella. What does this result indicate?

She is susceptible to chickenpox. ***She is susceptible to chickenpox*** - A negative test for serum antibodies to varicella indicates a **lack of protective immunity** to the varicella-zoster virus (VZV). - This woman has not previously been infected with VZV or vaccinated, making her **susceptible to primary infection (chickenpox)** upon exposure. *She is susceptible to zoster* - **Zoster (shingles)** is caused by the **reactivation of latent VZV** in individuals who have previously had chickenpox. - Since she tested negative for antibodies, she has not had chickenpox and thus **cannot harbor latent VZV** to reactivate. *She is immune to zoster* - Immunity to zoster implies that she has had chickenpox and subsequently developed a robust immune response to prevent viral reactivation. - A negative antibody test directly contradicts this, as it signifies no prior exposure or immune response. *She is immune to chicken pox* - Immunity to chickenpox is established by the presence of **varicella antibodies**, which are absent in this case. - A negative antibody result means she is **not immune** and is therefore at risk of contracting chickenpox if exposed.

Q: A child presented with bluish-white spots in the mouth followed by a rash. What is the genome of the most likely causative agent?

Enveloped virus with single-stranded RNA. ***Enveloped virus with single-stranded RNA*** - Bluish-white spots in the mouth (**Koplik spots**) followed by a rash are pathognomonic for **measles**, which is caused by the **measles virus**. - The measles virus is a **paramyxovirus**, characterized as an **enveloped, negative-sense, single-stranded RNA virus**. *Double stranded Naked RNA* - No major human pathogen belongs to this specific genomic and structural classification. - Most **dsRNA viruses** like **rotavirus** are **naked** but cause gastroenteritis, not measles. *Naked virus with single-stranded RNA* - Viruses like **rhinovirus** (common cold) or **poliovirus** fit this description but do not cause Koplik spots or measles. - **Naked viruses** lack a lipid envelope, making them generally more resistant to environmental factors. *Double stranded Enveloped RNA* - There are no known medically significant human viruses that are both **enveloped** and contain **double-stranded RNA**. - Viral genomes are typically either DNA or RNA, and RNA viruses are usually single-stranded (positive or negative sense) or double-stranded, with or without an envelope.

Q: The viruses of the Filoviridae family like Ebola and Marburg resemble which of the following morphologies?

Filamentous. ***Filamentous*** - Viruses in the **Filoviridae family**, including **Ebola** and **Marburg**, are characterized by their distinct **long, filamentous shape**. - This morphology is a key distinguishing feature visible under electron microscopy, contributing to their namesake ("filo" meaning "thread-like"). *Brick shaped* - **Brick-shaped morphology** is characteristic of **Poxviridae**, such as the **variola virus** (smallpox). - This shape is distinctly different from the thread-like structure of filoviruses. *Bullet shaped* - **Bullet-shaped viruses** are typical of the **Rhabdoviridae family**, which includes the **rabies virus**. - This shape is consistent and easily recognizable for this family, contrasting with the much longer and flexible filaments of filoviruses. *Spherical* - **Spherical morphology** is common among many virus families, including **influenza virus** (Orthomyxoviridae) and **human immunodeficiency virus (HIV)** (Retroviridae). - While many viruses are roughly spherical, filoviruses are specifically known for their elongated, non-spherical appearance.

Q: The following are parvovirus - related disease - population pairs. Identify the incorrect pair. 1. Aplastic anemia - Patient with hereditary hemolytic anemia 2. Non - immune hydrops - pregnant women 3. Erythema infectiosum - infants 4. Non - erosive arthritis - Patients of SLE

4. ***Non - erosive arthritis - Patients of SLE*** - While parvovirus B19 can cause **non-erosive arthritis**, it is not specifically associated with patients with **systemic lupus erythematosus (SLE)** as a common or unique presentation. Parvovirus B19-induced arthritis typically resolves spontaneously. [1] - The given pairing implies a direct and specific link between parvovirus B19 arthritis and SLE patients, which is inaccurate. *Aplastic anemia - Patient with hereditary hemolytic anemia* - This is a **correct pairing**. Parvovirus B19 preferentially infects and destroys erythroid progenitor cells, leading to a temporary cessation of red blood cell production. [1] - In patients with **hereditary hemolytic anemias** (e.g., sickle cell anemia, thalassemia), who have a rapid red blood cell turnover and depend on continuous erythropoiesis, this cessation can lead to a severe and life-threatening **aplastic crisis**. [1] *Non - immune hydrops - pregnant women* - This is a **correct pairing**. Parvovirus B19 infection in a pregnant woman can cross the placenta and infect the fetus. - Fetal infection can cause severe anemia and heart failure, leading to **non-immune hydrops fetalis**, a condition characterized by abnormal fluid accumulation in two or more fetal compartments. *Erythema infectiosum - infants* - This is a **correct pairing**. **Erythema infectiosum**, also known as "fifth disease," is the most common clinical manifestation of parvovirus B19 infection. [1] - It primarily affects **children** (including infants) and is characterized by a "slapped cheek" rash on the face followed by a lacy rash on the trunk and extremities. [1]

Q: Which virus can be identified by a PCR method and is endemic to India?

Chikungunya virus. ***Chikungunya virus*** - The **Chikungunya virus** is a mosquito-borne alphavirus that causes fever, severe joint pain, and rash, and is **endemic to India** and other tropical regions. - Diagnosis is commonly confirmed using **PCR** (polymerase chain reaction) to detect viral RNA in acute samples. *Ebola virus* - The **Ebola virus** causes severe hemorrhagic fever and is primarily prevalent in **Sub-Saharan Africa**, not endemic to India. - While it can be detected by **PCR**, its geographical distribution does not match the endemic criteria for India. *Yellow fever* - **Yellow fever virus** is transmitted by mosquitoes and is endemic to **tropical and subtropical areas of South America and Africa**. - India is not considered an endemic area for yellow fever, though it can be detected by **PCR**. *Hendra virus* - The **Hendra virus** is a zoonotic virus primarily found in **Australia**, transmitted from bats to horses and then to humans. - It is not endemic to India and thus does not fit the criteria of the question.

Q: A 23-year-old woman presents with vulvar ulcers and lymphadenopathy. Testing confirms primary HSV infection. Which of the following statements about HSV antibody development is correct?

IgG antibodies appear 2-3 weeks after infection and persist. ***IgG antibodies appear 2-3 weeks after infection and persist*** - Following primary HSV infection, the body mounts an immune response, with **IgG antibodies** typically becoming detectable approximately **2-3 weeks post-infection**. [1] - These **IgG antibodies** persist for life, providing long-term immunity and serving as a marker of past or latent infection. [1] *IgG appears immediately after infection* - The immune system requires time to generate a robust antibody response, so **IgG antibodies** do not appear immediately following infection. [2] - The initial immune response involves innate immunity and the production of **IgM antibodies** before IgG. [1], [2] *No antibody response occurs* - The body's immune system recognizes the viral antigens and mounts an antibody response to combat the infection. - Absence of an antibody response would imply a complete failure of the adaptive immune system, which is not the case in immunocompetent individuals with primary HSV. [1] *IgM and IgG appear simultaneously at 6 weeks* - **IgM antibodies** are produced earlier in the immune response compared to **IgG**. [2] - While both may be present at 6 weeks, their appearance is not simultaneous, with IgM preceding IgG, and IgG often detectable by 2-3 weeks, not waiting until 6 weeks. [1]

Question 1

Which of the following statements about herpes simplex virus (HSV) shedding is MOST accurate?

Accepted Answer

Asymptomatic shedding accounts for most sexual transmission

Answer

HSV-1 sheds more frequently than HSV-2 in the genital tract

Answer

Viral shedding occurs only during symptomatic episodes

Answer

Antiviral suppression completely eliminates viral shedding

Question 2

What is the mechanism behind the increased risk of HIV acquisition in individuals with genital herpes?

Accepted Answer

HSV disrupts epithelial barrier and recruits CD4+ cells

Answer

HSV glycoproteins enhance HIV binding to target cells

Answer

HSV inhibits local innate immune responses

Answer

HSV increases HIV viral load through transactivation

Question 3

A patient is a known case of thalassemia. Which of the following viruses would be responsible for attacking progenitor cells and causing aplastic anemia?

Accepted Answer

Parvovirus B19

Answer

CMV (Cytomegalovirus)

Answer

EBV (Epstein-Barr Virus)

Answer

Hepatitis C virus (HCV)

Question 4

Which viral infection is most likely responsible for triggering this aplastic crisis in the patient?

Accepted Answer

Parvovirus B19

Answer

Epstein-Barr Virus (EBV)

Answer

Hepatitis B Virus (HBV)

Answer

Cytomegalovirus (CMV)

Question 5

A pregnant woman, whose niece contracted varicella while living in the same house, tested negative for serum antibodies to varicella. What does this result indicate?

Accepted Answer

She is susceptible to chickenpox

Answer

She is susceptible to zoster

Answer

She is immune to zoster

Answer

She is immune to chicken pox

Question 6

A child presented with bluish-white spots in the mouth followed by a rash. What is the genome of the most likely causative agent?

Accepted Answer

Enveloped virus with single-stranded RNA

Answer

Double stranded Naked RNA

Answer

Naked virus with single-stranded RNA

Answer

Double stranded Enveloped RNA

Question 7

The viruses of the Filoviridae family like Ebola and Marburg resemble which of the following morphologies?

Accepted Answer

Filamentous

Answer

Brick shaped

Answer

Bullet shaped

Answer

Spherical

Question 8

The following are parvovirus - related disease - population pairs. Identify the incorrect pair.

1. Aplastic anemia - Patient with hereditary hemolytic anemia
2. Non - immune hydrops - pregnant women
3. Erythema infectiosum - infants
4. Non - erosive arthritis - Patients of SLE

Accepted Answer

4

Answer

1

Answer

2

Answer

3

Question 9

Which virus can be identified by a PCR method and is endemic to India?

Accepted Answer

Chikungunya virus

Answer

Ebola virus

Answer

Yellow fever

Answer

Hendra virus

Question 10

A 23-year-old woman presents with vulvar ulcers and lymphadenopathy. Testing confirms primary HSV infection. Which of the following statements about HSV antibody development is correct?

Accepted Answer

IgG antibodies appear 2-3 weeks after infection and persist

Answer

IgG appears immediately after infection

Answer

No antibody response occurs

Answer

IgM and IgG appear simultaneously at 6 weeks

Virology — MCQs

Virology — MCQs

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