Acquired Immune Deficiency Syndrome (AIDS): A sexually-transmitted disease caused by infection with the human immunodeficiency virus (HIV). AIDS is characterized by a loss of immune function, usually over several years, which makes the HIV-infected person susceptible to other infections.

Alkalinity: The presence of excess hydroxide ions compared to hydrogen ions (protons). The opposite of acidity; high on the pH scale.

Antimicrobial properties: The ability of any substance to inhibit the growth of microorganisms.

Antiviral agents: Compounds that inhibit the replication of a virus.

Attachment: The process by which a virus specifically binds its host cell to begin the process of viral replication.

Bacterial vaginosis: A bacterial infection of the vagina marked by a discharge and an odor.

Barrier methods: Contraception or disease control methods that utilize a physical barrier to limit the exchange of bodily fluids following sexual activity. Condoms and diaphragms are among the most commonly used barriers.

Broad-spectrum microbicide: A substance that can inactivate several types of pathogens to prevent the spread of sexually-transmitted diseases.

Carrageenan: A natural sulfated polymer and polysaccharide produced by algae.

Cervical cancer: A potentially deadly uncontrolled growth of cells of the cervix, which is the neck of a woman's uterus.

Chlamydia: A common sexually-transmitted disease of humans that is caused by the bacterium Chlamydia trachmatis.

Clinical trials: Medical testing of human subjects to determine the effectiveness of pharmaceutical products or treatment methods.

Commercial sex workers: People who engage in sexual activity in exchange for money.

Condom: A sheath that covers the penis to prevent semen from entering the vagina during sexual activity. A variation known as the female condom consists of a polyurethane sheath with a flexible polyurethane ring, which is inserted into the vagina much like a diaphragm, and a lining to protect the vaginal walls during sexual activity.

Contraception: The prevention of pregnancy.

Dextrin sulfate: A polysaccharide, or large carbohydrate molecule made of several sugars linked together, that is a specific type of sulfated polymer.

Diaphragm: A contraceptive device in the form of a shallow molded rubber cup that fits into the vagina over the cervix and is held in place by the vaginal muscles.

DNA viruses: Viruses that consist of a DNA genome surrounded by a protein coat.

Efficacy: The ability of a treatment mechanism or drug to achieve its goal under ideal conditions.

Epidemiology: The study of disease transmission and the distribution of diseases within communities.

Genetically engineered plant: A plant that has had its genome altered in order to produce desired effects.

Genital warts: Soft, cauliflower-like growths found in and around the genital regions.

Gonorrhea: A sexually-transmitted disease that causes urethritis and other complications in humans. It is caused by the bacterium Neisseria gonorrheae.

Herpesvirus: Any of a family of DNA viruses that mature in nuclei of infected cells and are the causative agents of some skin diseases.

Highly active antiretroviral activity (HAART): A treatment for AIDS which combines several antiviral agents that inhibit the growth of HIV.

Human immunodeficiency virus (HIV): The causative viral agent of AIDS.

Inhibitor of viral entry: A substance that prevents a virus from attaching to a host cell, thus preventing infection.

Lactic acid bacteria: Bacteria that produce lactic acid as a result of carbohydrate fermentation. One species of lactic acid bacteria that is part of the normal human vaginal microflora is Lactobacillus crispatus.

Lesions: Breakages in tissue.

Microflora: The normal population of microorganisms in a healthy organism.

Monoclonal antibodies: Proteins produced by the immune system, which can be synthesized in the laboratory in pure form by a single clone (population) of cells.

Non-nucleoside reverse transcriptase inhibitors: Compounds that inhibit an RNA-directed DNA polymerase, that do not mimic nucleosides.

Nucleoside reverse transcriptase inhibitors: Compounds that inhibit an RNA-directed DNA polymerase by mimicking nucleosides, the building blocks of nucleic acids.

Papillomavirus: Any of several DNA viruses that cause tumors of the epithelium.

Pathogens: Organisms that cause diseases.

Placebo: An inactive substance that is clinical trials to determine the efficacy of a medicinal product.

Proteinase inhibitors: Compounds that prevent proteinases from metabolizing proteins.

RNA viruses (retroviruses): Viruses that consist of an RNA genome surrounded by a protein coat. An RNA virus must use RNA-directed DNA polymerase to convert its genome to DNA so that new viral RNA can be synthesized.

Sexually-transmitted diseases: Infections that are passed from one person to another as a result of sexual activity.

Spermicide: A product that kills, immobilizes or inactivates sperm cells, which helps to prevent pregnancy.

Sulfated polymer: A large sulfur-containing molecule.

Syphilis: A sexually-transmitted disease caused by the spirochete bacterium Treponema pallidum.

Tenofovir: A nucleoside reverse transcriptase inhibitor and antiviral agent that has been shown to inhibit the replication of HIV.

Trichomoniasis: A sexually-transmitted disease caused by the protozoan Trichomonas vaginalis.

Toxicity: The quality of poisonousness or the ability of something to kill.

Urethritis: An inflammation of the urethra, the tube that carries urine from the bladder to the exterior of the body.

Yeast infection: An inflammation of the vagina caused by an overgrowth of Candida yeast.