Target cell populations of human immunodeficiency virus type 1 in peripheral blood lymphocytes with different chemokine receptors at various stages of disease progression.

We studied the distribution of human immunodeficiency virus type 1 (HIV-1) DNA in CCR5-positive and -negative peripheral blood lymphocyte populations in HIV-1-infected individuals. While HIV-1 DNA in the CCR5-positive population showed no correlation with CD4 count, the increase of total HIV-1 DNA with lower CD4 count was mainly contributed by the increase of HIV-1 DNA in the CCR5-negative population. This might indicate the change in coreceptor usage from CCR5 to CXCR4 in later stages of disease progression. However, some of the samples with a high viral DNA load in the CCR5-negative population did not have any characteristic of the V3 loop sequence that is compatible with CXCR4 usage or the syncytium-inducing (SI) phenotype. We also did not find any known characteristic change predictive of the SI phenotype in V1 and V2 sequences. Our findings showed that there might be a shift in target cell populations during disease progression, and this shift was not necessarily associated with the genetic changes characteristic of CXCR4 usage.