Inoculation of S. aureus into the MG through the teat canal induced the recruitment of IL-17-producing γδ T cells, IL-17pos (Th17) and IFN-γpos (Th1) lymphocytes, followed 5 days post-infection by an influx of CD4pos CD25pos (Treg) cells (114, 115). This evidence concerns the gene IL17A and infection.