Abstract
After interruption of highly active antiretroviral therapy, 15 out of 53 patients with the X4 HIV strain had a significantly larger decrease in CD4(+) T cell count (P = 0.001) and shorter length of treatment interruption (P = 0.02) than patients with the R5 strain. At treatment resumption, HIV inferred tropism switched from the X4 strain to the R5 variant in 9 patients (60%). These patients had a prolonged length of treatment interruption compared to that of those who still carried the X4 strain.