Looking for a Few Good Microbicides Candidates

Until recently, microbicide discovery was a by-product of the search for anti-HIV drugs. Early in the search for microbicides, for example, attention focused on detergents because of their ability to disrupt HIV’s coat. Most such easily testable candidates, however, failed as microbicides. Now that scientists know more about HIV’s life cycle,
they are beginning to identify multiple points at which the virus could be stopped.

Ideally, a microbicide should be:
• Colorless and odorless
• Inexpensive to manufacture and purchase
• Safe to use more than once a day and for long periods of time
• Effective against multiple STDs, including HIV/AIDS
• Fast-acting, long-lasting, and non-irritating
• Undetectable to either partner
• Available in contraceptive and non-contraceptive forms
• Available without a prescription

In theory, creating an effective topical microbicide should be easy. Simply identify chemicals that kill disease-causing organisms, blend the chemicals with an inert gel or foam, and place it in the vagina. Experience, however, has shown that the simple approach may not work.

The Research Pipeline 
Like a new drug or vaccine, topical microbicide development will follow a pathway—the research pipeline—from basic research to commercial production. The key points along the pipeline are basic research, product formulation and preclinical testing, and clinical testing.

Microbicide Q & A (3)

How would an HIV microbicide function?
An HIV microbicide could work in 5 different ways:
- Eliminating or inactivating pathogens.
A microbicide could inhibit HIV infection by breaking down the surface of the virus or pathogen.
- Create physical barriers. Gels or creams could offer a physical barrier between pathogens or viruses, and susceptible cells in the epithelium (cell wall) of the vagina or rectum.
- Strengthening the body's natural protection.
The body has numerous naturally sourced defense system that a microbicide might be able to supplement or enhance. For example, lactobacillus is a naturally occurring, "good" bacteria that helps protect the vagina by keeping its acidic environment. This natural acidity helps foster an inhospitable environment for a lot of pathogens, including HIV. A microbicide that supports the lactobacilli in carrying out this function might inhibit infection by HIV or STDs.
- Inhibiting viral entry.
A microbicide could inhibit viral or bacterial infection by interfering with the binding of viral proteins to cellular receptors. For example, infection with the HIV virus happens through binding of gp120 (on the outside of the virus) to receptors on a cell's membrane. A potential microbicide might interrupt this process by binding to receptors ahead of time, thus blocking the sites and preventing HIV attachment to the cell.
- Suppressing viral replication. Designed as gels or creams, anti-HIV medications that are already FDA-approved and available might be able to reduce replication of HIV in the vagina or rectum during sexual intercourse.