Nokea
To raise antibodies that interfere with the interaction of HIV with CD4+ T cells, vaccines should target which of the following HIV antigens
- A. gp41
- B. Reverse transcriptase
- C. gp120
- D. Matrix proteins
Correct Answer: C
Rationale: The correct answer is C: gp120. This is because gp120 is a key HIV antigen that plays a crucial role in binding to CD4 receptors on T cells, facilitating viral entry. By targeting gp120, vaccines can induce antibodies that block this interaction, preventing HIV from infecting CD4+ T cells. Conversely, choices A, B, and D (gp41, Reverse transcriptase, Matrix proteins) are not as effective targets for interfering with the CD4+ T cell interaction, as they do not directly impact the initial binding and entry process of HIV into the cells.
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Which T cell type is involved in directly killing infected or foreign cells?
- A. Helper T cells
- B. Cytotoxic T cells
- C. Regulatory T cells
- D. Memory T cells
Correct Answer: B
Rationale: The correct answer is B: Cytotoxic T cells. Cytotoxic T cells are responsible for directly killing infected or foreign cells by releasing toxic substances that induce apoptosis in the target cells. This process helps eliminate the threats to the body.
Helper T cells (Choice A) assist in coordinating immune responses but do not directly kill cells. Regulatory T cells (Choice C) play a role in suppressing immune responses to prevent autoimmunity but do not kill infected cells. Memory T cells (Choice D) are primed for rapid response upon re-exposure to a specific antigen but do not directly kill cells. Therefore, the correct choice is B as cytotoxic T cells are specifically designed for cell killing.
CD8+ T cells
- A. Have cytotoxic function
- B. Recognize antigen in the context of MHC I molecules
- C. Can kill virus-infected cells
- D. Can kill tumor cells
Correct Answer: E
Rationale: I apologize, but the question you provided does not have a correct answer option listed. Could you please provide the correct answer option for me to provide a detailed explanation of why it is correct and summarize why the other choices are incorrect?
Avian Influenza has not so far caused a human pandemic because
- A. Avian flu causes only mild infection in humans compared to birds
- B. Avian flu recognizes a variant of sialic acid found only on avian cells
- C. Avian flu recognizes a variant of sialic acid only found deep in the lung tissue of humans, not in the upper airways
- D. H5N1 is included in the composition of the annual trivalent inactivated vaccine
Correct Answer: C
Rationale: The correct answer is C because avian flu recognizing a variant of sialic acid only found deep in the lung tissue of humans, not in the upper airways explains why it has not caused a human pandemic. This specificity limits human-to-human transmission as the virus cannot efficiently attach in the upper airways where respiratory droplets are expelled. Choices A and B are incorrect because avian flu can cause severe infections in humans and recognizes a variant of sialic acid found in both birds and humans, not just avian cells. Choice D is incorrect as the presence of H5N1 in the annual trivalent vaccine does not prevent human pandemic potential.
APECED is a rare autoimmune disease caused by deficiency of
- A. CTLA-4
- B. AIRE
- C. Tregs
- D. TGF-β
Correct Answer: B
Rationale: The correct answer is B: AIRE. APECED (Autoimmune Polyendocrinopathy-Candidiasis-Ectodermal Dystrophy) is caused by mutations in the AIRE gene. AIRE is responsible for regulating the expression of self-antigens in the thymus, crucial for the development of immune tolerance. Deficiency in AIRE leads to the production of autoantibodies and autoimmune manifestations.
Incorrect options:
A: CTLA-4 is involved in downregulating immune responses but is not directly linked to APECED.
C: Tregs (regulatory T cells) play a role in immune tolerance, but APECED is not directly caused by their deficiency.
D: TGF-β is a cytokine involved in immune regulation, but its deficiency does not lead to APECED.
The nurse is assessing a client for signs and symptoms of systemic lupus erythematosus (SLE). Which of the following would be consistent with this disorder? (Select one that does not apply.)
- A. Discoid rash on skin exposed to sunlight
- B. Urinalysis negative for casts and protein
- C. Painful, deformed small joints
- D. Pain on inspiration
Correct Answer: A
Rationale: The correct answer is A: Discoid rash on skin exposed to sunlight. Systemic lupus erythematosus (SLE) commonly presents with a characteristic butterfly-shaped rash on the face, especially over the cheeks and nose, that worsens with sunlight exposure. The rash is not limited to skin exposed to sunlight. Choices B, C, and D are inconsistent with SLE. B: Urinalysis negative for casts and protein is not indicative of SLE, as renal involvement in SLE often presents with the presence of casts and protein in the urine. C: Painful, deformed small joints is more typical of rheumatoid arthritis, not SLE. D: Pain on inspiration is a symptom of pleurisy, which can occur in SLE but is not a defining feature.