Knowing, on the one hand, the capacity of SRLV to infect MDM and trigger the production of an M2 phenotype (above) and, on the other hand, the possible role of MR in SRLV entry and infection [31] and the increased production of MR upon IL-4 stimulation, we first studied env-mediated viral entry using for infection, pseudoviruses expressing the envelope protein of known SRLV strains (Ev1, CAEV-Co, Roccaverano, Seui) or VSV protein G (Figure 6a). This evidence concerns the gene ERVW-1 and infection.