Concerning with NLRs, which of the following is NOT correct

Correct Answer: C

Rationale: The correct answer is C because NLRs are not important for embryonic development in Drosophila. NLRs are primarily involved in immune responses by recognizing pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs) in the cytosol. Choice A is correct as NLRs are indeed cytosolic receptors for MAMPs and DAMPs. Choice B is correct as NOD receptors are a subset of NLRs. Choice D is correct as similar proteins to NLRs are also found in plants, known as NBS-LRR proteins. Therefore, the incorrect statement is C, as NLRs are not essential for embryonic development in Drosophila.

Correct Answer: B

Rationale: The correct answer is B because the 2009 H1N1 pandemic was caused by a newly assorted virus unrelated to existing human strains. This is atypical as typical pandemics are caused by animal strains. Option A is incorrect because the 2009 H1N1 pandemic did not emerge entirely as an assortment of human strains. Option C is incorrect as the 2009 H1N1 virus was not a variant of the 1918 H1N1 strain circulating in pigs. Option D is incorrect because the 2009 H1N1 pandemic did affect individuals across all age groups, including the very young.

Correct Answer: C

Rationale: The correct answer is C because a B cell epitope is not a part of the antibody molecule that contacts an antigen. B cell epitopes are specific regions on an antigen that bind to B cell receptors. Choice A is incorrect because denaturation can expose B cell epitopes. Choice B is incorrect because pathogens typically have multiple B cell epitopes. Choice D is incorrect because B cell epitopes can be found on various parts of pathogens, not just on the surface.

Correct Answer: C

Rationale: The correct answer is C because a given MHC molecule can bind only one peptide at a time. This is essential for the proper presentation of antigens to immune cells. MHC class I and class II molecules do not consist of two transmembrane protein chains (A), MHC class I molecules have one peptide-binding site while MHC class II molecules have one peptide-binding site (B), and MHC molecules on the cell surface typically have peptides bound to their peptide-binding sites, even in the absence of infection (D).

Correct Answer: C

Rationale: The correct answer is C because in response to Leishmania parasites, the activation of Th cells into Th1 effectors that secrete IFNγ is crucial for activating macrophages to eliminate the intracellular parasites. IFNγ enhances the microbicidal activity of macrophages, helping to control the infection. Choice A is incorrect because IL-4 is not required to induce the appropriate antibody response against Leishmania parasites. Choice B is incorrect because Th2 effectors secreting IL-4 would not activate macrophages effectively against Leishmania, which is an intracellular pathogen. Choice D is incorrect because in the case of Leishmania, a Th1-mediated response is most effective due to the need for macrophage activation by IFNγ.