Which of the following molecular interactions mediate signal 2 during activation of naïve T cells

Correct Answer: E

Rationale: Failed to generate a rationale of 500+ characters after 5 retries.

Correct Answer: D

Rationale: The correct answer is D because a strong cytotoxic T cell response can still effectively clear the virus even without neutralizing antibodies. Cytotoxic T cells directly kill infected cells, helping to control and eliminate the virus. Therefore, the vaccine would not result in failure to clear the virus. A) Incorrect: While the vaccine may not prevent infection, the presence of cytotoxic T cells would help in controlling and reducing the severity of the infection. B) Incorrect: The vaccine may indeed lessen the severity of the disease by aiding in the clearance of infected cells. C) Incorrect: A strong T cell response can provide broader protection against different variants of the virus.

Correct Answer: B

Rationale: The correct answer is B because upregulation of endothelial adhesion molecules is the first event during an acute inflammatory response. This event facilitates the initial recruitment of leukocytes, including neutrophils, to the site of inflammation. Extravasation of neutrophils (choice A) occurs after adhesion molecules are upregulated. Secretion of opsonins (choice C) and phagocytosis (choice D) occur later in the inflammatory response process after the neutrophils have been recruited to the site of inflammation.

Correct Answer: D

Rationale: The correct answer is D: Increased migration of dendritic cells from tissues to lymph nodes. Complement activation does not directly lead to the migration of dendritic cells. Complement activation can lead to increased recruitment of inflammatory cells (A), opsonization of pathogens (B), and lysis of pathogens (C). Dendritic cells typically migrate to lymph nodes to present antigens to T cells, but this process is not directly mediated by complement activation.

Correct Answer: D

Rationale: Step 1: Adjuvants like AS03 induce danger signals by activating innate immunity, enhancing the response to the vaccine. Step 2: Adjuvants generally boost the innate immune response by increasing antigen presentation and cytokine production. Step 3: Adjuvants create a slower release of antigen, forming an antigen depot which prolongs immune stimulation. Summary: Choice D is correct because adjuvants like AS03 do induce danger signals, boost the innate immune response, and create a slower release of antigen, leading to enhanced vaccine efficacy. Choices A, B, and C are incorrect as they do not encompass all the effects of adjuvants in flu vaccines.