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To produce better flu vaccines, we want:
- A. To block spreading of the infection by inducing a cytotoxic T cell response that would directly prevent viral entry into uninfected cells
- B. To induce the formation of strain-specific neutralizing antibodies that would prevent viral entry into uninfected cells
- C. To induce antibodies able to recognize HA across different strains by targeting less variable regions of HA
- D. All of the above is reasonably expected to improve the success of flu vaccines
Correct Answer: D
Rationale: The correct answer is D because all the options contribute to improving flu vaccines. A cytotoxic T cell response can help block viral spread, strain-specific neutralizing antibodies can prevent viral entry, and targeting less variable regions of HA with antibodies can improve recognition across strains. Each approach addresses different aspects of the immune response to enhance vaccine efficacy. Therefore, combining these strategies can lead to a more comprehensive and effective flu vaccine. Options A, B, and C alone are not sufficient as they only target specific aspects of the immune response, while option D encompasses a holistic approach for better vaccine success.
You may also like to solve these questions
Why don't we have a successful HIV vaccine?
- A. The high mutation rate of HIV interferes with the generation of a protective memory response
- B. Because it is difficult to induce mucosal immunity that would block the sexual transmission of the virus
- C. Because HIV targets immune cells
- D. All of the above represent challenges for the creation of an effective HIV vaccine
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.
The percentage of developing thymocytes undergoing negative selection in the thymus is close to
- A. 90%
- B. 50%
- C. 25%
- D. 10%
Correct Answer: A
Rationale: The correct answer is A (90%). Negative selection in the thymus eliminates self-reactive T cells. The process ensures self-tolerance. The majority of developing thymocytes are removed during negative selection, making it close to 90%. Choices B, C, and D are incorrect because negative selection eliminates a high percentage of thymocytes, not a lower percentage as indicated in those options.
Pattern recognition receptors (PRR) can be found
- A. In soluble form in the blood
- B. In the cytosol of cells
- C. On endosomal membranes
- D. All of the above are correct
Correct Answer: D
Rationale: Pattern recognition receptors (PRRs) are a class of receptors that recognize specific molecular patterns associated with pathogens. They can be found in various locations within the body, including in soluble form in the blood (Choice A), in the cytosol of cells (Choice B), and on endosomal membranes (Choice C). Therefore, the correct answer is D, "All of the above are correct," as PRRs can indeed be located in all of these locations. PRRs play a crucial role in the innate immune response by detecting and responding to pathogens, making their presence in multiple cellular compartments essential for effective immune surveillance and defense.
Select the property that applies only to pathogens:
- A. Replicate in (or on) a host
- B. Infect host cells
- C. Cause disease in a host with normal immune functions
- D. Are transmitted between individuals of a given species
Correct Answer: C
Rationale: The correct answer is C because pathogens are microorganisms that specifically cause disease in a host with normal immune functions. Pathogens have mechanisms to evade or overcome the host's immune system, leading to the development of diseases. Choices A and B are characteristics of both pathogens and non-pathogenic organisms. Choice D is incorrect because not all pathogens are transmitted between individuals of the same species; some pathogens can be transmitted from animals to humans or through environmental sources.
Why do we constantly need new flu vaccines?
- A. Because flu viruses mutate frequently due to their error-prone RNA polymerase
- B. Because completely new variants can be created from an assortment of previously circulating strains due the segmented nature of the viral genome
- C. Because antibodies generated in vaccinated people are short-lived and need to be generated again with a new vaccine injection
- D. Both A and B are correct
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.