A drug combination developed by the California company Gilead Sciences has shown promise in stopping the spread of HIV in a small test group of monkeys, scientists said. The drug combo, currently sold under the trade name Truvada, contains the compounds tenofovir and emtricitabine, and is currently approved by the FDA to help those already infected with HIV from getting sicker. The US Centers for Disease Control reported in February that, in a test it conducted, Truvada protected six monkeys from contracting the AIDS virus. The monkeys were given Truvada and then exposed to a deadly combination of monkey and human AIDS viruses. Despite 14 weekly doses of the virus, none of the monkeys became infected. By comparison, most of the monkeys that received the viruses without Truvada in a previous experiment became infected. The CDC hopes to determine if Truvada can help prevent human HIV transmission by testing it in people in Botswana, the Associated Press reported.