A.Carbone and F.Oteri work on the Spike protein of SARS2 in collaboration with the group of F.L.Cosset at CIRI in Lyon, expert in non-replicative retroviral pseudoparticles. Based on coevolution analysis of patient sequences and sequences from bats and other species, they aim at identifying key residues in the Spike protein involved in the entry mechanism of the virus in human cells. In the past, the two groups successfully combined their computational and experimental methods to unravel critical features of the original HCV fusion mechanism.