South Africans will take part in a clinical trial starting next year that is part of the global search for an HIV vaccine. Scientists will give 1500 women in sub-Saharan Africa, and 2400 gay men in the US and South America, "broadly neutralising" antibodies through an intravenous drip to see if the antibodies protect them from HIV.Broadly neutralising antibodies protect against multiple strains of HIV but only some people produce them naturally.It is believed that if a vaccine can "teach" the body to make this type of antibody the recipient will be protected from HIV.Researchers at the HIV Vaccine Trials Network will make the antibodies in a laboratory and give them to people through a drip every two months during the three-year trial."We don't know if this will be effective," said Glenda Gray, head of the South African vaccine trial and a member of the network."We are in the golden era of HIV vaccine research. It has taken us 30 years to get here."Gray is leading the South African trial, in which 252 participants are being given a slightly modified version of the R144 vaccine, which gave Thais a 31% reduced probability of contracting HIV.The modified R144 vaccine is being evaluated concurrently with the broadly neutralising antibody study.South African participants will receive eight injections over 18 months. If the results indicate that the vaccine is effective it will be tested on 5000 people next year.The South Africans are being given an extra injection and a booster to make the vaccine last longer and increase its efficacy...