VDJ gene rearrangement takes place in

Correct Answer: C

Rationale: Rationale: VDJ gene rearrangement occurs during lymphocyte development to generate diverse antigen receptors. This process occurs in the bone marrow, specifically in the early stages of B cell development. In the bone marrow, B cell precursors undergo VDJ recombination to create unique antibody specificity. Germinal centers are sites for B cell activation and proliferation, not gene rearrangement. Lymph nodes and spleen are secondary lymphoid organs where mature lymphocytes are activated, not where VDJ recombination occurs.

Correct Answer: E

Rationale: In this question, the correct answer is C) gp41. This protein is a component of the HIV envelope that plays a crucial role in the fusion of the virus with the host cell membrane. By targeting gp41 therapeutically, we can interfere with this binding process, preventing HIV from entering T lymphocytes and replicating within them. Option A) Reverse transcriptase (RT) is responsible for converting the viral RNA into DNA once the virus has entered the host cell, not for the initial binding process. Option B) Viral proteases are enzymes that cleave viral proteins into functional components but do not directly impact the binding of HIV to T lymphocytes. Option D) Matrix protein is involved in the assembly of the virus particle and not in the binding to host cells. Understanding the specific functions of these HIV proteins is essential for developing effective therapeutic strategies to combat the virus. By targeting gp41, researchers can potentially develop drugs that block HIV entry into host cells, thereby inhibiting viral replication and spread. This knowledge is crucial for students studying immunology, virology, and infectious diseases, as it highlights the importance of targeting specific viral components to design effective treatments.

Correct Answer: B

Rationale: The correct answer is B: DAMPs formation. Alum is known to trigger the release of damage-associated molecular patterns (DAMPs), which are endogenous molecules released by damaged cells. This activation of DAMPs plays a crucial role in initiating and enhancing the immune response. The other choices, TLR4, NOD1, and TLR9, are receptors involved in recognizing specific pathogen-associated molecular patterns (PAMPs) rather than DAMPs. Therefore, they are not directly triggered by alum. This makes choice B the correct answer based on the known mechanism of action of alum as an adjuvant.

Correct Answer: A

Rationale: The correct answer is A. Chronic granulomatous disease (CGD) is caused by mutations of the NADPH oxidase genes, leading to defective respiratory burst in neutrophils. Neutrophils are recruited to sites of infection normally in CGD. Therefore, choice A is incorrect. Choices B, C, and D are incorrect because CGD is indeed associated with defective respiratory burst of neutrophils due to mutations in NADPH oxidase genes, leading to recurrent bacterial infections.

Correct Answer: D

Rationale: The correct answer is D: Complement activation. Phagocytosis by macrophages involves engulfing and digesting pathogens. Complement activation occurs through a separate pathway involving a series of proteins that enhance the immune response. Phagocytosis does not directly lead to complement activation. Choices A, B, and C are outcomes of phagocytosis in macrophages: Respiratory burst involves production of reactive oxygen species, nitric oxide production helps destroy pathogens, and antigen presentation is important for activating other immune cells.