HIV-1 infection of nonhuman primates does not lead to the acquired immunodeficiency syndrome seen in humans. The basis for this lack of disease progression in these animals is still unknown. In this study, primary nonhuman primate peripheral blood mononuclear cells (PBMC) were tested for their susceptibility to in vitro infection by several different primary HIV- 1 isolates representing distinct subtypes or clades. None of the five HIV-1 subtypes tested were able to readily establish an infection in chimpanzee or baboon PBMC, as determined by p24 antigen capture assays. To address the mechanism of in vitro resistance to HIV-1 infection, PBMC were analyzed for HIV deceptor mRNA expression and cell surface expression. Flow cytometry analysis of the nonhuman primate PBMC demonstrated that they do express CD4, CCR3, CCR5, and CXCR4 on their cell surface. Therefore, the level of restriction in the virus replication cycle does not appear to lie at the point of entry in these cells.
- CC chemokine receptor 5
- CXC chemokine receptor 4
- Flow cytometry
- Nonhuman primates
- Peripheral blood mononuclear cells