A gene has been identified that could predict the susceptibility of an individual to contracting HIV or developing AIDS, a report in the Journal of AIDS reveals. Scientists at the National Institute of Allergy and Infectious Diseases discovered the gene, called RANTES. Variations in the gene means it works in two ways: while it could double a person's susceptibility to contracting HIV, it also delays the length of time for progression to AIDS in HIV infected people by about 40%. Dr Philip Murphy and his team looked at RANTES gene variations in HIV-positive and HIV-negative people who where participating in the Multicenter AIDS Cohort Study. They found that the variations involved single nucleotide polymorphisms (SNPs). One SNP, which appeared to increase the activity of RANTES gene, occurred significantly more often in HIV-positive than in HIV-negative individuals. This provides a possible explanation as to why some people are more susceptible to HIV. To explain why the RANTES gene is also able to delay the progression of HIV to AIDS the team carried out laboratory experiments. Dr David McDermott, the lead author, postulates that the RANTES gene produces an immune system molecule, the normal function of which is to cause inflammation. This opens up spaces between cells allowing HIV agents to enter the body more easily. However, to stimulate inflammation RANTES attaches to the surface of T cells, preventing HIV from doing so, and therefore preventing the virus from spreading so easily. RANTES gene's success in hindering HIV has led companies to try to develop RANTES-based drugs to slow HIV progression, but Dr McDermott points out, "The results of our studies support those efforts, but researchers must remember that higher RANTES levels may increase the likelihood of acquiring HIV."