The National Institute of Allergy and Infectious Diseases has awarded the University of Pittsburgh Graduate School of Public Health a five-year, $7.2 million grant to test two microbicide gels to curb male-to-female HIV transmission.

According to researchers, the RC101 microbicide will block HIV from entering CD4 cells, and the CSIC microbicide will deactivate an enzyme the virus needs to replicate once inside the cell. Researchers are also developing two microbicide application methods, including a topical film and a vaginal ring that releases the active ingredient over time.

Applied to the vagina or rectum of the receptive sexual partner, microbicide gels aim to prevent or reduce the risk of HIV transmission in the absence of condoms. While several microbicides are in development, none has been proved to be effective.

“The HIV/AIDS epidemic remains uncontrolled in many regions in the world,” Phalguni Gupta, MD, professor and assistant chairman of the graduate school’s Department of Infectious Diseases and Microbiology, said in a statement. “In developing countries, HIV is most often spread through unprotected heterosexual intercourse, creating a great need for new ways to prevent transmission beyond the condom whose use is often at the discretion of men.”