A study published on Sunday 19 July in the electronic version of the journal Science has revealed new data about the mechanism by which some people naturally maintain the AIDS virus (HIV) at barely detectable levels while in others it quickly develops beyond control. The article is the result of international collaboration between researchers in Europe, Australia and the United States and is based on a large-scale study of genetic differences between patients infected with HIV. This is the first research study of its type to be published in the field of infectious diseases.

Taking part in the study were the researchers Josep M. Miró from the Department of Medicine, consultant to the Infectious Diseases and AIDS Unit at the Hospital Clínic de Barcelona-IDIBAPS, and Javier Martínez-Picado, an ICREA research professor from the irsiCaixa Foundation of the Hospital Germans Trias i Pujol. The research, which also counted with the collaboration of the Hospital de la Santa Creu i Sant Pau and the Hospital Mútua de Terrassa, was carried out with the most up to date genomic and biocomputing technologies, which were used to analyse 550,000 variations of the complete human genome in 486 predominantly European patients preselected from 33,000 potential candidates. These variations, known as Single Nucleotide Polymorphisms (SNP) are differences in genomes that only affect a nucleotide or base. The ability to identify the specific variations is essential in determining the progression of the disease.

In the course of the research an association study was performed to determine the principal genetic variations that play the most significant role in controlling the viral infection. The results indicate two genetic variants related to the immune system. These variations are located in a genetic region responsible for determining the capacity of the immune response against various infectious diseases such as AIDS that is located on the short arm of chromosome 6 in genes that control the molecular systems HLA-B and HLA-C. These systems activate the immune system to locate and destroy cells that have been infected with HIV. The study has also identified a third genetic variant also located on chromosome 6 that is involved in the deterioration of the immune system.

The genetic variants related to the genes that encode the molecular systems HLA-B and C could explain up to 15% of the variation in the quantity of the virus between patients – the highest correlation with the immune response described to date – while the third genetic variant would account for up to 5.8%. Nevertheless, the contribution of other genetic regions involved in this process should also be studied.

The article reveals data that will be particularly useful in the development of a future vaccine against the disease. It also represents a step forward in the area of personalized medical research, which is aimed at identifying the most suitable drugs for individual patients according to their genetic characteristics. The research was coordinated by Amalio Telenti, codirector of the Institute of Microbiology at the University of Lausanne, Switzerland, and by David Goldstein, director of the Center for Population Genomics and Pharmacogenetics at the Duke Institute for Genome Sciences & Policy  in the US. The project is overseen by the international consortium Center for HIV-AIDS Vaccine Immunology (CHAVI), which was founded in July 2005 to promote research into new vaccination strategies against the AIDS virus. The project was expanded with the incorporation of other European research groups and an Australian group under the name EuroCHAVI, which performed the study in collaboration with the Duke Institute.
The article will be published in the journal Science in paper format in August.