ARA | Microbicide FAQs

Microbicides: Frequently Asked Questions

What are microbicides?

A microbicide is a topical substance that could substantially reduce the transmission of HIV and other sexually transmitted diseases when inserted into the vagina or rectum. It could take many forms, including gels, creams, suppositories, films, or in combination with a sexual lubricant. Further, it offers the potential for an HIV prevention option that both women and men could easily control, without the knowledge of their sexual partner.

Will different microbicides be needed for the vagina and the rectum?

Most likely, yes. The rectum and vagina have different structures. The vagina is like a closed pouch whereas the rectum is more like an open-ended cavity. Thus, more microbicide will probably be needed to cover the entire rectum. Additionally, HIV is more easily transmitted via anal sex than through vaginal sex. In the rectum, there are more immune cells, which make the rectal mucosa more vulnerable to HIV infection. Also, the rectal lining is more fragile than the vaginal lining. Therefore, rectal tissue is more likely to get irritated, tear, and become infected with HIV.

Are microbicides a cure for AIDS?

Microbicides would not be a cure, but rather could be another HIV prevention option. Ideally, both a microbicide and an HIV vaccine would be used because it is highly likely that no one approach will end the AIDS pandemic. Vaccines and microbicides will have different but complimentary roles to play in HIV prevention.

If we find a microbicide, would we still need to use condoms?

Condoms would still be the preferred option. But, for people who can’t or won’t use condoms (sex workers, disenfranchised women, populations of developing nations, etc.), this would be another prevention option that they could control privately.

How would microbicides work?

A microbicide could work in 5 different ways:

1. Killing or inactivating pathogens. A microbicide could inhibit HIV infection by breaking down the surface of the virus or pathogen.

2. Create physical barriers. Gels or creams could provide a physical barrier between pathogens or viruses and vulnerable cells in the epithelium (cell wall) of the vagina or rectum.

3. Strengthening the body’s normal defenses. The body has several naturally occurring defense mechanisms 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 maintaining its acidic environment. This natural acidity helps foster an inhospitable environment for many pathogens, including HIV. A microbicide that supports the lactobacilli in performing this function might inhibit infection by HIV or STDs.

4. 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 occurs through binding of gp120 (on the outside of the virus) to receptors on the cell's membrane. A microbicide could potentially interrupt this process by binding to receptors in advance, thus blocking the sites and preventing HIV attachment to the cell.

5. Inhibiting viral replication. Formulated as gels or creams, the already available anti-HIV medications might be able to suppress replication of the HIV in the vagina or rectum during sexual intercourse.

Ideally, microbicide would by combining all 5 ways together!

What would the ideal microbicide be like?

Some characteristics of an ideal microbicide:

• It would be active against a range of STDs, including HIV. Ideally, a microbicide would work against all STDs (syphilis, warts, herpes, Chlamydia, gonorrhea, HPV, Hepatitis B, etc.) but this will be difficult to achieve. Some STDs are bacterial and some are viral.

• It would not irritate the rectal and vaginal tissue (like Nonoxydol-9 did)

• It would be available with or without spermicide (to prevent pregnancy)

• It would be effective for a long period of time

• It would be acceptable and easy to use (it wouldn’t taste or smell bad, could easily be carried around or stored)

• It would be stable at high temperatures (meaning that it won’t go bad)

• It would not be absorbed into the rest of the body, meaning that it would stay in the rectum or vagina

How can I get more involved in the microbicide issue?

The microbicide issue needs both activists and volunteers to test microbicide candidates.

If you are interested in activism, please contact the Global Campaign for Microbicide Development: www.global-campaign.org

If you are interested in volunteering for a microbicide study, please contact AIDS Research Alliance at 310/358-2429 or email us at info@aidsresearch.org