Our laboratory has been focusing on the SIV/macaque model for mucosal SIV transmission to investigate the early events of HIV/SIV infection. We are currently using a recombinant SIV tagged with a “green fluorescent protein” (GFP) as a sensitive tool to monitor infected cells in vivo.  This sensitive marker will allow us to 1) examining the early mechanisms of genital transmission in macaques, particularly in cells at the initial infection site;  2) to investigate the timing, intensity and route of viral spread from the site of infection to lymphoid organs and blood and 3) to explore the early generation of mucosal immune responses at viral entry.  Our investigations will give us a more detailed understanding picture of viral spread from the infected cells in the mucosal barrier and the role of host defenses early in infection.  This understanding is critical to the development of effective vaccines.