Its name is CRF02_AG, and this subtype of the human immunodeficiency virus (HIV) is increasingly prevalent in the French HIV-positive population. According to data presented at the poster last week at the 26th International Conference on Retroviruses and Opportunistic Infections (CROI), its percentage increased from 14% before 2010 to 22% in 2016. Although CRF02_AG has been known since the onset epidemic, recent evidence suggests that it is more virulent and transmissible than other subtypes of viruses.
"Since 1999, we have analyzed yearly isolated viruses in patients during their primary infection," Diary "Dr. Marie Loree Chais (St. Louis Hospital, AP-XP) explains. We monitor the transmitted resistance, the diversity of viruses and the occurrence of new recombinants and transmission clusters, or groups of patients infected with viruses of similar species. "
Only 5% of the cases in the 90s
The researchers compare data from 1,121 infected patients between 2014 and 2016, of which 90% are men, of which 70% are men who have sex with men. CRF02_AG is recombination of subtype A and D. Very old, it was introduced in France by patients from sub-Saharan Africa. In the early 1990s, only 5% of the infected prima was affected by this subtype. Patients subtype B represented a vast majority of patients.
While nothing distinguished them a few years ago, these sub-types were recently associated with a viral significantly higher, compared with what is noticed in the case of infection with subtype B viruses, the majority in France. The CRF02_AG subtype is also more common in clusters with a large number of patients. These results could suggest the capacity of this subtype to spread faster.
"Even if we exclude patients from Sub-Saharan Africa, generally diagnosed later, we notice that this difference is maintained. Therefore, it would potentially be more virulent and more portable," adds Dr. Chai, who does not need to worry excessively: " this subtype corresponds to treatments, as well as others. "
However, this possible and recent increased virulence intrigues doctors. "The works of Francis Barrin (University of Tours, Ed) have already shown that CRF02_AG is opposed to the wider antibody wide spectrum neutralizer, adds Dr. Chaix. We will act on a national database of surveillance and we will study the hypothesis of a possible recent change in the genome of this subtype: we will divide it completely and look for possible differences in structural and non-structural proteins. "
Almost half of the French receiving-infected in the identified "cluster"
The authors also mapped the "clusters", ie groups of patients infected with phylogenetically related strains. Clusters are groups of patients infected with very close viruses, often in the same place or region or in the same mode of transmission. "We notice that 41% of patients with primary infection are part of the cluster," explains Dr. Chai. Patients who do not belong to an identified cluster are most often diagnosed after a primary infection when the disease becomes chronic. "Of the 6,000 annual infections in France, only 600 to 1,000 are diagnosed throughout the year," says Dr. Chai.
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