Virology Practice Questions

Q: During the asymptomatic latent phase of AIDS, the virus is actively proliferating and can be found in association with which of the following?

Follicular dendritic cells in lymph nodes. **Explanation:** The "asymptomatic" or clinical latency phase of HIV is a misnomer; while the patient is clinically stable, the virus is **actively replicating** within the lymphoid tissues. **Why Option B is Correct:** During this phase, the lymph nodes act as a major reservoir for the virus. HIV particles are trapped on the surface of **Follicular Dendritic Cells (FDCs)** in the germinal centers of lymph nodes. These FDCs are coated with HIV virions (bound via complement and Fc receptors), which then infect passing CD4+ T cells. This continuous interaction leads to the gradual depletion of CD4+ cells, eventually resulting in the breakdown of the follicular architecture and the onset of overt AIDS. **Why the other options are incorrect:** * **A. B lymphocytes:** While B-cell hyperplasia occurs due to polyclonal activation in HIV, B cells are not the primary site of viral proliferation or sequestration during latency. * **C. Ganglion cells:** These are associated with the latency of **Herpes Simplex Virus (HSV)** and **Varicella-Zoster Virus (VZV)**, not HIV. * **D. Oligodendrocytes:** These cells are the target of the **JC virus**, leading to Progressive Multifocal Leukoencephalopathy (PML) in AIDS patients, but they are not the site of HIV proliferation during clinical latency. **High-Yield Clinical Pearls for NEET-PG:** * **Primary Reservoir:** The "Latent Reservoir" of HIV is primarily **Resting Memory CD4+ T cells**, but the site of active proliferation during clinical latency is the **Lymph Node (FDCs)**. * **Viral Set Point:** The level of steady-state viremia at the end of the acute phase predicts the rate of progression to AIDS. * **Coreceptor Switch:** HIV typically uses **CCR5** (M-tropic) in early stages and may switch to **CXCR4** (T-tropic) in later stages.

Q: Which of the following lymphomas is associated with HTLV-I virus infection?

Adult T-cell leukemia and lymphoma. **Explanation:** **Adult T-cell Leukemia/Lymphoma (ATLL)** is the correct answer because it is directly caused by the **Human T-lymphotropic virus type 1 (HTLV-1)**. HTLV-1 is a retrovirus that infects CD4+ T-cells. The viral **Tax protein** plays a critical role in oncogenesis by activating host cell genes involved in proliferation and inhibiting tumor suppressor genes (like p53), leading to the malignant transformation of T-cells. **Analysis of Incorrect Options:** * **Burkitt’s Lymphoma:** This is strongly associated with the **Epstein-Barr Virus (EBV)**, particularly the endemic form found in Africa, and involves a c-myc translocation t(8;14). * **B-cell Lymphoma:** While HTLV-1 affects T-cells, B-cell lymphomas are more commonly associated with EBV, HHV-8 (Primary Effusion Lymphoma), or Hepatitis C. * **Hodgkin’s Disease:** While EBV is found in about 40-50% of Hodgkin lymphoma cases (especially the Mixed Cellularity subtype), there is no established causal link with HTLV-1. **High-Yield NEET-PG Pearls:** * **Clinical Presentation:** ATLL often presents with aggressive lymphadenopathy, hepatosplenomegaly, lytic bone lesions, and **hypercalcemia**. * **Morphology:** A characteristic finding on peripheral blood smear is the presence of **"Flower cells"** (cloverleaf nuclei). * **Transmission:** HTLV-1 is transmitted via breastfeeding (most common), sexual contact, and blood transfusion. * **Endemic Areas:** It is most prevalent in Japan, the Caribbean, and parts of Central Africa.

Q: Which of the following is true regarding viral antibodies?

Antibodies are formed against viral surface proteins.. **Explanation:** **1. Why Option C is Correct:** The humoral immune response primarily targets the **viral surface proteins** (capsid proteins in non-enveloped viruses and glycoproteins in enveloped viruses). These surface antigens are the first to be recognized by B-lymphocytes. Antibodies against these proteins—specifically **neutralizing antibodies**—are clinically significant because they prevent the virus from attaching to and entering host cells, thereby conferring immunity. **2. Why Other Options are Incorrect:** * **Option A:** Interferons (IFN-α and IFN-β) are part of the **innate immune response** and are produced within hours of viral infection. Antibodies (adaptive immunity) take several days to weeks to develop. Therefore, **interferon appears before antibodies.** * **Option B:** Antibodies are generally formed against **proteins** (antigens). Viral nucleic acids (DNA/RNA) are sequestered inside the viral core and are not typically immunogenic during a natural infection unless they are recognized by intracellular receptors like TLRs. * **Option D:** While IgM appears early (within the first week), the **maximum antibody levels (peak titers)**, particularly IgG, are usually reached between **2 to 4 weeks** after the initial exposure, not within one week. **Clinical Pearls for NEET-PG:** * **Neutralizing Antibodies:** These are specific antibodies that bind to surface proteins and inhibit viral infectivity. * **Seroconversion:** The interval during which antibodies first become detectable in the blood. * **Diagnostic Marker:** IgM indicates an **acute/recent infection**, while IgG indicates a **past infection or chronic state**. * **Window Period:** The time between infection and the point where antibodies become detectable (e.g., in HIV).

Q: Which of the following is a known reservoir for the Ebola virus?

Ebola virus. **Explanation:** The **Ebola virus**, a member of the *Filoviridae* family, causes severe hemorrhagic fever. In the context of its natural life cycle, the primary reservoir is believed to be **fruit bats** (specifically genera *Hypsignathus monstrosus*, *Epomops franqueti*, and *Myonycteris torquata*). The virus is transmitted to humans through contact with infected bushmeat (monkeys, forest antelope) or directly via bat excreta. *Note: The question structure provided implies a self-referential identification; however, in a clinical sense, the "reservoir" refers to the ecological niche where the pathogen survives.* **Analysis of Options:** * **Option A (Japanese Encephalitis Virus):** This is a Flavivirus. Its natural reservoir is **pigs and water birds** (like herons and egrets), and it is transmitted to humans via the *Culex* mosquito. * **Option C (Zika Virus):** Another Flavivirus. While it primarily circulates between humans and *Aedes* mosquitoes, its sylvatic (jungle) reservoir involves **non-human primates**. * **Option D (Plasmodium falciparum):** This is a protozoan parasite, not a virus. Its primary reservoir and definitive host is the **female Anopheles mosquito**, while humans serve as intermediate hosts. **High-Yield Clinical Pearls for NEET-PG:** * **Transmission:** Human-to-human spread occurs through direct contact with **broken skin or mucous membranes** and bodily fluids (blood, vomit, feces). * **Pathogenesis:** Ebola causes "cytokine storm" and severe DIC (Disseminated Intravascular Coagulation). * **Diagnosis:** RT-PCR is the gold standard during the acute phase; ELISA for IgM/IgG is used later. * **Biosafety Level:** Ebola requires **BSL-4** containment, the highest level of laboratory security.

Q: Epstein-Barr virus (EBV) is associated with which of the following conditions, except?

Anal carcinoma. **Explanation:** The correct answer is **Anal carcinoma** because it is primarily associated with **Human Papillomavirus (HPV)**, specifically high-risk types 16 and 18, rather than the Epstein-Barr Virus (EBV). **Why the other options are associated with EBV:** * **Nasopharyngeal Carcinoma:** EBV has a strong oncogenic association with the undifferentiated type of nasopharyngeal carcinoma, particularly prevalent in Southern China and SE Asia. It involves the expression of viral proteins like LMP-1 in epithelial cells. * **Carcinoma of the Tonsil:** While many oropharyngeal cancers are HPV-related, EBV is also linked to certain epithelial malignancies of the Waldeyer’s ring (including the tonsils), often following a similar pathogenic pathway to nasopharyngeal carcinoma. * **Infectious Mononucleosis (Glandular Fever):** This is the classic acute clinical manifestation of primary EBV infection, characterized by the triad of fever, pharyngitis, and lymphadenopathy, with the presence of atypical lymphocytes (Downey cells) on peripheral smear. **High-Yield Clinical Pearls for NEET-PG:** * **EBV Receptor:** It binds to the **CD21** molecule (CR2) on B-lymphocytes. * **Other EBV Associations:** Burkitt Lymphoma (starry-sky appearance), Hodgkin Lymphoma (Mixed cellularity subtype), Oral Hairy Leukoplakia (in HIV patients), and Post-transplant lymphoproliferative disorder (PTLD). * **Diagnosis:** The **Paul-Bunnell Test** (detecting heterophile antibodies) is the classic screening test for Infectious Mononucleosis. * **Mnemonic for HPV:** HPV is associated with "Below the belt" cancers (Cervical, Anal, Vulvar, Penile) and Oropharyngeal squamous cell carcinoma.

Q: What is the primary receptor through which M-tropic HIV strains bind?

CCR5. **Explanation:** The entry of HIV into host cells is a multi-step process involving the viral envelope glycoprotein **gp120**. This protein first binds to the **CD4 receptor** on T-cells or macrophages, causing a conformational change that allows gp120 to interact with a specific **chemokine co-receptor**. 1. **Why CCR5 is correct:** M-tropic (Macrophage-tropic) strains, also known as **R5 strains**, utilize the **CCR5** co-receptor. These strains are typically responsible for the initial infection and are found in the early stages of the disease. They primarily infect macrophages, monocytes, and memory T-cells. 2. **Why CXCR4 is incorrect:** T-tropic (T-cell-tropic) strains, or **X4 strains**, utilize the **CXCR4** co-receptor. These strains emerge in the later stages of HIV infection, show a preference for naïve T-cells, and are associated with a rapid decline in CD4 counts and progression to AIDS. 3. **Why CXCR5 is incorrect:** CXCR5 is a chemokine receptor primarily involved in B-cell homing to lymph nodes; it does not serve as a primary co-receptor for HIV entry. **High-Yield Clinical Pearls for NEET-PG:** * **Maraviroc:** A CCR5 antagonist (entry inhibitor) used in HIV treatment; it is ineffective against X4 (T-tropic) strains. * **Genetic Resistance:** Individuals with a homozygous **CCR5-Δ32 mutation** (a 32-base pair deletion) are virtually resistant to infection by M-tropic HIV-1. * **Coreceptor Switch:** The progression of HIV often involves a "phenotypic switch" where the virus evolves from using CCR5 (M-tropic) to CXCR4 (T-tropic). * **gp41:** While gp120 handles attachment, **gp41** is responsible for the actual fusion of the viral envelope with the host cell membrane.

Q: A sexually active woman presents for a routine gynecologic exam with a Pap smear report indicating cervical intraepithelial neoplasia. In situ hybridization reveals the presence of human papillomavirus (HPV) type 16 genomes within the neoplastic cells. Which of the following processes is required for HPV to cause cancer development?

Integration of the viral genome. **Explanation:** The progression of Human Papillomavirus (HPV) infection to cervical carcinoma is fundamentally dependent on the **integration of the viral genome** into the host cell DNA. 1. **Why Option A is correct:** In benign lesions (warts), the HPV genome exists as an episome (circular, extrachromosomal). However, in malignant lesions, the viral DNA integrates into the host genome. This integration typically occurs at the **E1/E2 open reading frame**, leading to the **disruption of the E2 gene**. Since the E2 gene normally functions as a negative regulator (repressor) of the **E6 and E7 oncogenes**, its loss leads to the uncontrolled overexpression of E6 and E7. * **E6** binds to and degrades the **p53** tumor suppressor protein. * **E7** binds to and inactivates the **pRb** (Retinoblastoma) protein. The loss of these "molecular brakes" leads to unrestricted cell cycle progression and genomic instability. 2. **Why the other options are incorrect:** * **Option B:** Loss of E6 and E7 would prevent oncogenesis, as these are the primary drivers of malignancy. * **Option C:** While mutations occur in many cancers, the specific oncogenic transformation by HPV is driven by gene expression changes following integration, not random viral mutations. * **Option D:** Viral replication (the production of new virions) occurs in the superficial layers of the epithelium and usually leads to cell death (lysis), which is contrary to the immortalization required for cancer. **High-Yield Clinical Pearls for NEET-PG:** * **High-risk HPV types:** 16 and 18 (associated with ~70% of cervical cancers). * **Low-risk HPV types:** 6 and 11 (associated with Condyloma acuminatum). * **Koilocytosis:** The hallmark cytological finding on Pap smear (perinuclear halo with wrinkled "raisinoid" nuclei). * **Vaccine:** Gardasil-9 covers types 6, 11, 16, 18, 31, 33, 45, 52, and 58.

Question 1

Which of the following statements is/are true regarding viral infections and their associated manifestations?

Accepted Answer

Epstein-Barr virus (EBV) causes lymphomatous lymphoma, Respiratory Syncytial Virus (RSV) causes bronchiolitis, and Erythema infectiosum is characterized by a 'slapped cheek' appearance.

Answer

Kaposi's sarcoma is caused by HHV-6, Epstein-Barr virus (EBV) causes lymphomatous lymphoma, and Respiratory Syncytial Virus (RSV) causes bronchiolitis.

Answer

Epstein-Barr virus (EBV) causes lymphomatous lymphoma and Respiratory Syncytial Virus (RSV) causes bronchiolitis.

Answer

Kaposi's sarcoma is caused by HHV-6 and Erythema infectiosum is characterized by a 'slapped cheek' appearance.

Question 2

During the asymptomatic latent phase of AIDS, the virus is actively proliferating and can be found in association with which of the following?

Accepted Answer

Follicular dendritic cells in lymph nodes

Answer

B lymphocytes

Answer

Ganglion cells

Answer

Oligodendrocytes

Question 3

Which of the following lymphomas is associated with HTLV-I virus infection?

Accepted Answer

Adult T-cell leukemia and lymphoma

Answer

Burkitt's lymphoma

Answer

B-cell lymphoma

Answer

Hodgkin's disease

Question 4

Which of the following is true regarding viral antibodies?

Accepted Answer

Antibodies are formed against viral surface proteins.

Answer

Antibodies appear before interferon.

Answer

Antibodies are formed against viral nucleic acid.

Answer

Maximum antibody levels are seen within one week.

Question 5

What is true about Congenital Rubella Syndrome?

Accepted Answer

It can result in a chronic infection.

Answer

The virus can be isolated up to 6 months after birth.

Answer

The classic triad of CRS includes cataracts, cardiac defects, and hearing loss.

Answer

Congenital Rubella infection is most serious during the first trimester of pregnancy.

Question 6

Which of the following is a known reservoir for the Ebola virus?

Accepted Answer

Ebola virus

Answer

Japanese encephalitis virus

Answer

Zika virus

Answer

Plasmodium falciparum

Question 7

Which of the following statements about the virus described is/are true? The virus is enveloped, has club or petal shaped projections, and possesses a positive-sense single-stranded RNA genome with the largest genome among RNA viruses. Diseases caused by these viruses include SARS and MERS. The reservoir for SARS is horseshoe bats, with likely spread from palm civets and cats to humans. Symptoms of MERS appear within a day following contact with an infected patient. SARS is more severe than MERS. MERS infection is more severe in individuals with pre-existing illnesses like diabetes and heart diseases.

Accepted Answer

The statement regarding enveloped nature, projections, genome type, SARS/MERS causation, and MERS severity in those with pre-existing illness is true.

Answer

The statement regarding enveloped nature, projections, genome type, SARS/MERS causation, reservoir, and SARS severity is true.

Answer

The statement regarding enveloped nature, projections, genome type, SARS/MERS causation, and reservoir is true.

Answer

All the presented statements are true.

Question 8

Epstein-Barr virus (EBV) is associated with which of the following conditions, except?

Accepted Answer

Anal carcinoma

Answer

Carcinoma of the tonsil

Answer

Nasopharyngeal carcinoma

Answer

Infectious mononucleosis

Question 9

What is the primary receptor through which M-tropic HIV strains bind?

Accepted Answer

CCR5

Answer

CXCR4

Answer

CXCR5

Answer

Any of the above

Question 10

A sexually active woman presents for a routine gynecologic exam with a Pap smear report indicating cervical intraepithelial neoplasia. In situ hybridization reveals the presence of human papillomavirus (HPV) type 16 genomes within the neoplastic cells. Which of the following processes is required for HPV to cause cancer development?

Accepted Answer

Integration of the viral genome

Answer

Loss of HPV E6 and E7 genes

Answer

Mutation of the virus

Answer

Viral replication

Virology — MCQs

Virology — MCQs

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