Flu neuraminidase is

Correct Answer: D

Rationale: The correct answer is D because flu neuraminidase is a surface protein that allows the release of newly formed viral particles and it is also the target of Tamiflu. Neuraminidase helps the virus spread by cleaving sialic acid from host cells, facilitating the release of viral particles. Tamiflu inhibits neuraminidase, preventing the spread of the virus. Option A is incorrect because neuraminidase does not directly help the virus escape the host immune response. Option B is partially correct but incomplete without mentioning Tamiflu. Option C is also partially correct but incomplete without mentioning the role of neuraminidase in releasing viral particles.

Correct Answer: D

Rationale: The correct answer is D, "All of the above." T cells help B cells undergo isotype switching by providing cytokines. They also help B cells produce antibodies against protein antigens by activating them. T cells provide signal 2 of activation to B cells through the interaction of CD40 on B cells with CD40L on T cells. Therefore, all of these functions are critical for the collaboration between T and B cells in the immune response.

Correct Answer: A

Rationale: The correct answer is A because the meeting of naïve T cells and dendritic cells is not facilitated by the presence of naïve B cells. Naïve T cells interact with dendritic cells in the paracortex of lymph nodes, not with naïve B cells. The movement of T cells along connective tissue networks aids in their interaction with dendritic cells, and this interaction may supply the T cell with activation Signal 1, which is essential for T cell activation. Overall, the incorrect choices (B, C, and D) are actually true statements regarding the meeting of naïve T cells and dendritic cells, making them incorrect options.

Correct Answer: B

Rationale: The correct answer is B because Ehrlich proposed that each cell producing antibodies would express several receptors, each specific for different antigens, whereas Burnet proposed that each single antibody-producing cell expresses only one type of receptor. This is the main difference between the two theories. Ehrlich's concept of multiple receptors per cell allows for a broader range of specificity and diversity in the immune response. The other choices are incorrect because they do not directly address the main difference between the two theories as outlined above. Choice A is incorrect because both Ehrlich and Burnet emphasized the importance of specificity, but they differed in their views on receptor diversity per cell. Choice C is incorrect because it focuses on the identity of soluble antibodies and receptors, which is not the main differentiator between the two theories. Choice D is incorrect as it mentions the release of soluble antigen receptors, which is not the main point of differentiation between Ehrlich and Burnet's theories.

Correct Answer: C

Rationale: The correct answer is C: ROS (Reactive Oxygen Species) is not a PAMP (Pathogen-Associated Molecular Pattern) because it is not a specific molecular pattern derived from pathogens. PAMPs are recognized by the innate immune system to trigger an immune response. Viral dsRNA, peptidoglycan, and flagellin are all examples of PAMPs as they are specific molecules commonly found in pathogens that can be recognized by pattern recognition receptors (PRRs) on immune cells, leading to activation of the immune response.ROS, on the other hand, are reactive molecules produced by host cells in response to pathogens but are not specific molecular patterns derived from pathogens. Therefore, ROS is not considered a PAMP.