The new mutation concerns another gene (Transportin-3 or TNPO3) and is much rarer: it was discovered years ago in the same family in Spain, suffering from an ultra-rare muscular disease, called muscular dystrophy of belts type 1F.
Doctors found that HIV researchers were interested in the same gene separately because it plays a role in the transport of the virus inside the cells.
So they contacted geneticists from Madrid, who had the idea of trying to infect, in the laboratory, the blood of members of this Spanish family with the AIDS virus.
The experiment came as a surprise: the lymphocytes of those who had this ultra-rare muscle disease were naturally resistant to HIV. The virus could not get into it.
"It helps us to understand much better the transport of the virus in the cell," says José Alcamí, the virologist at the Carlos III Institute of Health in Madrid, who conducted the research published in the American journal PLOS. Pathogens.
HIV is certainly the best known of all viruses, he says, "but there are still many things we do not know well. For example, it is not known why 5% of patients who are infected do not develop AIDS. There are mechanisms of resistance to infection that we understand very badly.
The road is still long to exploit this flaw to produce a new drug. But the discovery of this natural resistance confirms that the TNPO3 gene is another interesting target to block the road to the virus.