CD26 EXPRESSION CORRELATES WITH ENTRY, REPLICATION AND CYTOPATHICITY OF MONOCYTOTROPIC HIV-1 STRAINS IN A T-CELL LINE

Experiments to identify cell determinants involved in HIV-1 tropism re vealed a specific decrease in the expression of the T-cell activation antigen CD26 after monocytotropic (M-tropic) but not T-cell line-tropi c (T-tropic) virus infection of the PM1 T-cell line. The level of CD26 expression in single-cell clones of PM1 correlated with the entry rat e and cytopathicity of M-tropic HIV-1 variants, resulting in preferent ial survival of cells with low CD26 levels after infection. Experiment s with recombinant viruses showed that the third hypervariable region of the envelope gp120 plays an important role in this selection proces s. This study identifies CD26 as a key marker for M-tropic human immun odeficiency virus type 1 (HIV-1) infection and suggests a mechanism fo r the early loss of CD26-expressing cells in HIV-1-infected individual s.