We next examined if the absence of Sdc1 ectodomains underlies the decreased susceptibility of Sdc1-/- mice to listeriosis by injecting purified Sdc1 ectodomains into Sdc1-/- mice at 6 h pi, a time point where Lm infection-induced Sdc1 shedding is maximal in Wt mice. This evidence concerns the gene SDC1 and listeriosis.