South Africa begins an important clinical trial of an experimental vaccine against AIDS. <br/><br/>More than 30 years of efforts to develop an effective vaccine for HIV have not borne desired result, however for the first time since the virus was identified in 1983, scientists think that they have found a promising candidate. <br/><br/>It is one of the biggest clinical trials involving the disease ever undertaken and has revived hopes in the scientific community of a solution in the challenge against AIDS.