Microbicides are compounds that can be applied inside the vagina or rectum to protect against sexually transmitted infections (STIs) including HIV. They can be formulated as rinses, gels, creams, films, or suppositories. Microbicides may or may not have spermicidal activity (contraceptive effect). At present, an effective microbicide is not available, but several candidate products are under development.
The initial focus of the PREVENT Program is the development of a rectal microbicide having the plant-derived lectin Q-GRFT as the antiviral ingredient. What we learn in the program will help guide development of safe and effective vaginal and rectal microbicides that can be used by both men and women.
The need for a microbicide that can be used rectally by women and men having anal sex is compelling. HIV is transmitted about ten times more easily rectally than it is vaginally, with a frequency (from partners with chronic HIV infection) of about 0.8% per act of intercourse compared with 0.08%. Not only is transmission easier with anal sex, but some data suggest that heterosexual couples may be less likely to use condoms when they have anal sex than when they have vaginal sex (possibly because the risk of pregnancy is removed). Thus, anal sex may be a significant contributor to HIV transmission among heterosexuals, as it already is among men who have sex with men.
People who practice unprotected receptive anal intercourse (URAI) represent the population most vulnerable to HIV-1 transmission due to the high preponderance of HIV target cells in the rectal mucosa and mucosal trauma commonly associated with RAI. Although the global incidence of HIV-1 is declining, the opposite is occurring in populations of men who have sex with men (MSM) and transgender women in both developed and developing regions. In 2010, 63% of new HIV-1 diagnoses in the US were in MSM, demonstrating that prevention of transmission associated with URAI should be a domestic public health priority. HIV-1 sub epidemics among MSM belonging to racial and ethnic minorities are particularly acute, highlighting the urgent need for attention to the preventative health needs in communities where MSM are especially stigmatized.
A good source of information on microbicides in development is the Microbicide Trials Network (MTN) web portal. The MTN is an HIV/AIDS clinical trials network established in 2006 by the National Institute of Allergy and Infectious Diseases (NIAID), with co-funding from the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) and the National Institute of Mental Health, all part of the U.S. National Institutes of Health (NIH). The MTN brings together international investigators and community and industry partners whose work is focused on the development and rigorous evaluation of promising microbicides. The MTN is also committed to the development of dual purpose products that would offer women a means for both HIV protection and contraception. Similarly, the HIV.gov web portal offers valuable information on microbicides, current clinical studies, and links to other HIV/AIDS resources.
Another resource portal is AVAC. Originally the AIDS vaccine advocacy coalition, AVAC's mission has expanded to global advocacy for HIV prevention using any and all tools available, including microbicides. AVAC uses education, policy analysis, advocacy, community mobilization and a network of global collaborations to accelerate ethical development and global delivery of biomedical HIV prevention options. Guidance can also be found at IRMA. Founded in 2005, the International Rectal Microbicide Advocates (IRMA) is a Chicago-based global network of over 1,200 advocates, policymakers and leading scientists from six continents working together to advance a robust rectal microbicide research and development agenda. IRMA’s goal is to support the creation of safe, effective, acceptable and accessible rectal microbicides for the women, men, and transgender individuals around the world who engage in anal intercourse.
These sites list current issues, research initiatives, on-going clinical studies, and support resources for HIV/AIDS prevention and management.