A site of intense B cell proliferation in the lymph node is

Correct Answer: A

Rationale: The correct answer is A: Germinal center. Germinal centers are specialized regions within lymph nodes where B cells undergo intense proliferation, somatic hypermutation, and class switching to generate high-affinity antibodies. This process is crucial for the adaptive immune response. Paracortex (B) contains T cells, not B cells. Medulla (C) is mainly involved in filtering lymph. Infected tissue (D) is not a specific site for B cell proliferation.

Correct Answer: D

Rationale: The correct answer is D because T regulatory cells are known to suppress immune responses and promote immune tolerance, which is opposite to causing immunity. Choice A is incorrect because T regulatory cells are indeed generated in the thymus upon expression of Foxp3. Choice B is incorrect as T regulatory cells can also be generated in the periphery in response to cytokines. Choice C is incorrect as T regulatory cells are known to inhibit effector T cells to regulate immune responses.

Correct Answer: B

Rationale: The correct answer is B: Hepatitis B. Recombinant vaccines are made by inserting genetic material from a pathogen into another organism to stimulate an immune response. Hepatitis B vaccine is produced using recombinant DNA technology to create a non-infectious protein that triggers an immune response against the hepatitis B virus. DPT, BCG, and Measles vaccines are not examples of recombinant vaccines as they are made using different methods without genetic engineering.

Correct Answer: C

Rationale: The correct answer is C because the statement that SARS coronavirus is also the causal agent of MERS is false. MERS (Middle East Respiratory Syndrome) is caused by a different coronavirus called MERS-CoV. SARS-CoV caused the 2003 epidemic with a 10% mortality rate, which aligns with statement A. Statement B is correct as SARS-CoV does cause an acute infection of the lungs known as acute respiratory distress syndrome. Statement D is also true as SARS-CoV is believed to have been transmitted from bats to civets and then to humans. Therefore, the incorrect statement is C.

Correct Answer: B

Rationale: The correct answer is B: Caspase 1. Caspase 1 is responsible for the cleavage of pro-IL-1β into its active form IL-1β. This process involves the activation of Caspase 1 by various inflammasomes upon sensing danger signals. Pro-caspase 1 (Choice A) is the inactive precursor form of Caspase 1 and is not involved in processing IL-1β. Procaspase 8 (Choice C) and Caspase 8 (Choice D) are part of the extrinsic apoptosis pathway and are not directly involved in the processing of IL-1β. Therefore, the correct choice is Caspase 1 as it specifically cleaves pro-IL-1β to its active form.