Which of the following about Influenza virus is NOT correct

Correct Answer: C

Rationale: The correct answer is C because the release of newly formed virus from the infected cell is actually mediated by Neuraminidase (NA), not Hemagglutinin (HA). 1. Influenza virus is indeed an RNA virus (Choice A). 2. In humans, influenza primarily infects lung epithelial cells (Choice B). 3. Hemagglutinin (HA) helps the virus enter host cells, while Neuraminidase (NA) helps release viral particles from infected cells (Choice C is incorrect). 4. Tamiflu is a Neuraminidase (NA) inhibitor, which prevents the release of viral particles, aiding in the treatment of influenza infections (Choice D).

Correct Answer: C

Rationale: The correct answer is C: Low antibiotic use. The hygiene hypothesis suggests that reduced exposure to infections, which can happen with low antibiotic use, can lead to an increased risk of immune diseases. Antibiotics can disrupt the balance of gut microbiota, which plays a crucial role in immune system development. A: Small family size may not necessarily protect against immune diseases as it does not directly relate to exposure to infections. B: Good sanitation can reduce the spread of infections but may not necessarily protect against immune diseases. D: Living in "westernized" countries is a broad factor and does not directly address the impact of low antibiotic use on immune diseases.

Correct Answer: D

Rationale: The correct answer is D. Choice A is correct because flu viruses mutate frequently due to their error-prone RNA polymerase, leading to new strains. Choice B is correct because the segmented nature of the viral genome allows for reassortment of different strains, creating completely new variants. Therefore, new vaccines are needed to target these evolving strains. Choice C is incorrect as the need for new vaccines is primarily driven by the genetic variability of the virus, not solely by the short-lived nature of antibodies. Thus, choices A and B together provide a comprehensive explanation for the constant need for new flu vaccines.

Correct Answer: D

Rationale: The correct answer is D because all the statements in choices A, B, and C are valid reasons why we don't have a successful HIV vaccine. A: HIV has a high mutation rate, making it challenging to generate a protective memory response. B: Inducing mucosal immunity is difficult to block sexual transmission, a common route of HIV infection. C: HIV targets immune cells, which hinders the immune system's ability to mount an effective response. Therefore, all these factors combined pose significant challenges for creating an effective HIV vaccine.

Correct Answer: C

Rationale: The correct answer is C: Transplantation. MHC proteins play a crucial role in transplant rejection by presenting antigens to T cells, initiating an immune response against foreign tissues. This discovery was significant in understanding transplant immunology. Choices A, B, and D are incorrect because innate immunity involves nonspecific defense mechanisms, allergies are mediated by IgE antibodies, and autoimmunity involves the immune system attacking self-antigens, none of which directly relate to the discovery of MHC proteins in transplantation studies.