1. Weill Medical College of Cornell University, New York, NY 10065, USA
2. Infectious Disease Clinical Research Program, San Antonio Military Medical Center, Ft. Sam Houston and Lackland AFB, TX 78234, USA
3. Veterans Administration Research Center for AIDS and HIV-1 Infection, South Texas Veterans Health Care System, San Antonio, TX 78229, and University of Texas Health Science Center, San Antonio, TX 78229, USA