Chimpanzee CXCR4 and CCR5 act as coreceptors for HIV type 1.

Chemokine receptors are molecules involved in the fusion of immunodeficiency viruses after their attachment. As chimpanzees are the animal model for infection by HIV-1, we cloned and sequenced chimpanzee CXCR4 and CCR5 from PBMCs. Chimpanzee CXCR4 was found to be identical to human CXCR4, which provides an explanation for the sensitivity of chimpanzees to lymphotropic isolates of HIV-1. Chimpanzee CCR5 showed two substitutions with respect to human CCR5. However, we show that the macrophage-tropic isolate HIV-1-Ba-L can use chimpanzee CCR5 as a fusion receptor. Therefore, the resistance of chimpanzee PBMCs to infection by macrophage-tropic isolates of HIV-1 is unlikely to be due to substitutions in CCR5.