A 36-year-old man with a history of a positive anti-HIV antibody test comes to the clinic with fever,sore throat,nonproductive cough,and weight loss.This patient has had a partner for 8 years with whom he has frequently engaged in unprotected sexual intercourse.The partner is a healthy 29-year-old man who is HIV negative.The partner's relative "resistance" to HIV infection may be due to a loss-of-function mutation in which of the following proteins?

Question

Quizplus · Accepted Answer

CCR5 is one of the coreceptors required for human immunodeficiency virus (HIV)infection in vivo.Individuals who do not express the normal CCR5 chemokine receptor because of genetic mutations are resistant to HIV infection despite repeated exposure.This finding underscores the importance of CCR5 as a cofactor in mediating HIV viral fusion with the host cell membrane.Interestingly,many HIV-infected individuals transition from the production of virus that uses CCR5 (macrophage-tropic virus),early in the disease to virus that binds to CXCR4,another chemokine receptor (T cell line tropic virus)late in the disease.A loss-of-function mutation in CD4 would also "protect" an individual from HIV infection,but because this individual would also lack CD4⁺ T cells,he would not present as a healthy 29-year-old man.

A 36-Year-Old Man with a History of a Positive Anti-HIV