Furthermore, we observed a functional improvement in the viral Envs from the LTNP-EC and vLTNP individuals to those of chronic Modern glycoproteins: these data support that the deficient Env fusion and transfer capacities observed in the Envs of viruses from LTNP-EC and vLTNP phenotypes have been enhanced in the viruses from individuals with progressive infection, particularly in those of the Modern group. This evidence concerns the gene ART4 and infection.