HIV-1 may revert to less pathogenic strain a few days after starting HAART

Previous study findings indicate that highly active antiretroviral therapy (HAART) can cause a shift from HIV-1 strains that use the CXCR4 T cell coreceptor (X4) to less pathogenic strains that use the CCR5 coreceptor (R5).

Dr Burger and colleagues characterized the HIV-1 strains of 15 women with advanced disease who were started on HAART. Prior to antiretroviral therapy, X4 strains were the predominant viral population. After initiation of HAART, the predominant viral population reverted back to the less pathogenic R5 strains that are often found soon after HIV infection. No dual-tropic viruses were found in any of the 525 biological clones tested.

Analysis of data from two patients revealed that the shift to R5 strains occurred within three days of starting HAART, Dr Burger told participants at the 41st Annual Interscience Conference on Antimicrobial Agents and Chemotherapy. Within two weeks of therapy, X4 strains were completely suppressed.

“In February, we published a report that showed that HAART can cause a shift back to R5 strains in patients with advanced disease who have mostly X4 strains at baseline,” Dr Burger said.

“In the current study, we took our previous findings further by looking more closely at the dynamics of the response,” Dr Burger said. “In the previous study, the time points at which we assessed the viral populations were months apart,” he stated. “In the present study, we wanted to see how rapidly coreceptor utilization changes so, for a few patients, we used time points that were only a couple of days apart,” he explained.

“Our studies indicate that HAART not only changes the quantity of HIV but also the quality of the virus,” Dr Burger noted. This may, in part, explain why certain patients do well clinically on HAART despite not achieving total viral suppression, he added.

H Burger and others. Preferential Suppression of CXCR4 Specific HIV-1 Strains by Antiviral Therapy and Dynamics of Response. Oral Presentation 1322.