Identify a gene associated with the immune system that reduces the effectiveness of the AIDS virus vaccine

Identify a gene associated with the immune system that reduces the effectiveness of the AIDS virus vaccine

Antonio Caruz. (Photo: F. Discover)

Researchers from the ‘Immunogenetics’ research group at the University of Jaén (Spain) have identified a gene that promotes a lower rate of infection with the AIDS virus in people vaccinated in pilot trials against this disease. Although the definitive vaccine against this pandemic does not yet exist, the identification of the gene will serve to know in advance which people have a ‘genetic barrier’ against HIV and who are most vulnerable to becoming infected.

This gene, called CR2, determines that the probabilities of infection are lower or higher depending on the expression that manifests in the genetic code of each individual. In the case of HIV, it is the fourth gene studied in the entire world scientific literature to determine the efficacy of future vaccines.

With this, the objective of the experts is to know what factors influence the efficacy of vaccines to make a more rational design of them in the future. In parallel, this knowledge allows identifying those people in whom vaccination would produce better protection against infection. However, they warn that if the overexposure of a person to contract the AIDS virus is high, genetics does not intervene in any case as a defense in case of high exposure to the virus by sexual means.

 To obtain these results, collected in the article entitled ‘Association of complement C3d receptor 2 genotypes with the acquisition of HIV infection in a trial of recombinant glycoprotein 120 vaccine’ and published in the journal AIDS, the team randomly selected a population of about 700 men, all participating in an AIDS vaccine trial in which a total of 5,000 volunteers were recruited. The profile of these individuals was similar: of European descent, uninfected and with a high risk profile for contracting the disease. In addition, part of this group was vaccinated and another was part of the placebo group. After three years of study and continuous evaluation, of all 273 people had been infected compared to 402 who were not.

After analyzing the blood samples from these two groups, they observed that within the group of vaccinated people this gene influences the infection rate after vaccination and is always expressed. “The percentage of individuals that can become infected with AIDS depends on their genetics, their DNA. This gene, associated with the function of innate immunity against viruses, fungi, bacteria or parasites, varies according to the genetic code of the people ”, details the researcher at the University of Jaén Antonio José Caruz, responsible for this work.

The analyzed gene is part of the genetic code of any human being. But as with other genes, their expression can vary. “Like we all have the gene that expresses the color of the eyes, there is a variant that determines the tonality in each person. The same thing happens here: there are people to whom this gene will act as a barrier against the AIDS virus, while in others it will not have such a function ”, clarifies Caruz.

However, they clarify that in this case of AIDS disease, genetic predisposition does not influence if overexposure is high. “We thought that genetic protection occurred in some cases yes and in others no, but we have verified that if the person has a high profile for contracting HIV, whether or not they have that variant of the gene that we analyze does not affect it,” says Caruz.

With this premise, the team from the University of Jaén has analyzed the interaction between genetics and an individual’s risk factors when contracting AIDS. “Genetics protects in cases of low level of exposure to the virus, but not in cases of high risk of sexual infection,” says the UJA researcher.

Currently, they have to replicate the results obtained in this work in other clinical trials to validate their conclusions. “We must return to the same premise but do it now with another population group, for example, among many other factors, to ensure that we reach the same point,” Caruz warns.

This work has been funded by the Ministry of Science and Innovation, the Hospital of Jaén, the Hospital of Valme, the University of Málaga, the University of California and a private entity in San Francisco. (Sources: F. Discover and NCYT® | ( /

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