This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. These experiments will provide important preliminary data for the development of the SIV foreskin/penile macaque challenge model. Based on the finding from the Merck STEP trial, in which vaccinated men with a foreskin were more likely to become HIV+, we propose that the foreskin challenge route should be utilized as a mucosal challenge route in future SIV vaccines. Optimizing the foreskin/penile challenge route will be important to test vaccines via this important mucosal route in the SIV/monkey model. These experiments utilize a coinfection model with the bacteria Haemophilus Ducreyi (causative agent of chancroid) to evaluate the factors that influence SIV infection via the foreskin. The most recent experiment is one in which foreskin/penile SIV transmission is assessed following the induction of H. Ducreyi infection, with the H. Ducreyi being administered to the foreskin area of the macaques via two different infection routes (intradermal and subcutaneously). Assessment of these experiments is currently underway.