Genetic characterization of human immunodeficiency virus type 1 Tat before and after highly active antiretroviral therapy.

Two HIV-infected individuals were followed for changes in the first exon of Tat. Plasma virus collected at 2 months after commencement of highly active antiretroviral therapy (HAART) was compared with the virus collected before initiation of HAART. This short-term therapy significantly reduced the plasma viral burden and also helped modest CD4 recovery in the blood. One of the two individuals (ACG) showed only one form of the Tat before commencement of HAART whereas five different forms (including a form identical to the pre-HAART sample) were found in the post-HAART sample. Some of the post-HAART clones showed a difference of 12.8% suggesting that the source of virus replication might be a reservoir. In the other patients multiple variants of the virus were found within each time point and also between two time points. This patient also showed a debilitating mutation (25-C/R) in three clones suggesting that some of the post-HAART viral forms were not viable in this patient. The dS/dN ratios in the patients were >2 suggesting lack of positive selection.