September 22, 2013. In an article entitled, ‘Immune clearance of highly pathogenic SIV infection’ published in September 11, 2013, issue of Nature (doi:10.1038/nature12519), the lead author Scott G Hansen with twenty five other associates from the Vaccine and Gene Therapy Institute and Oregon National Primate Research Center of Oregon Health & Science University, USA, have developed an HIV/AIDS vaccine candidate which appears to have the ability to completely clear an AIDS-causing virus from the body. It is being tested through the use of a non-human primate form of HIV, called simian immunodeficiency virus (SIV) which causes AIDS in monkeys. To date, HIV infection has only been cured in a very small number of highly-publicized but unusual clinical cases in which HIV-infected individuals were treated with anti-viral medicines very early after the onset of infection or received a stem cell transplant to combat cancer. The reason the body cannot clear HIV on its own is the ability of the virus to trigger an insufficient immune response. This allows the infection to evade T-cells and other key components of the defense of the body. The new vaccine supplements the inadequate immune response by introducing thecytomegalovirus (CMV). The research group discovered that pairing CMV with SIV had a unique effect. They found that a modified version of CMV engineered to express SIV proteins generates and indefinitely maintains so-called ‘effector memory’ T-cells that are capable of searching out and destroying SIV-infected cells. In the current study, infected monkeys protected by the vaccine lost signs of replication-competent SIV at several sites for weeks to months. Plasma- and tissue associated SIV could not be detected by ultrasensitive assays. With all positive outcomes, the research team now hopes to develop a CMV-vector vaccine that is safe enough to be tested in humans. [Summarized by Samsad Razzaque, Research Associate in Plant Bioth lab.DU. ]