<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A 49-year-old homeless man comes to the emergency department because of fatigue, cough, and worsening shortness of breath for 2 weeks. He was diagnosed with HIV-infection 25 years ago but has never had any symptoms. He has always refused to take antiretroviral medication. Pulmonary examination shows diffuse crackles over bilateral lower lung fields. An x-ray of the chest shows diffuse, symmetrical interstitial infiltrates. His serum level of beta-d-glucan is elevated. Further testing shows a heterozygous mutation that prevents entry of HIV into macrophages. Which of the following proteins is most likely affected by the mutation in this patient?? A: ICAM-1, B: CCR5, C: Gp120, D: CD4, E: P antigen,  <response>: This is a question about HIV infection and mutation affecting HIV entry into macrophages. The patient has longstanding HIV infection but has never had symptoms until now, when he presents with respiratory symptoms and chest x-ray findings consistent with Pneumocystis pneumonia PCP. His elevated beta-d-glucan level also supports PCP. The question asks which protein is most likely affected by a mutation that prevents HIV entry into macrophages in this patient.The main options for HIV entry into host cells are:- CD4: primary receptor for HIV gp120 on T cells - CCR5: coreceptor for HIV gp120, allows fusion and entry into macrophages- CXCR4: alternate coreceptor for HIV entry into T cellsSince the mutation affects entry specifically into macrophages, the CCR5 coreceptor is most likely affected.B: CCR5 