PIGR and infection: This may explain the results from an early study, which showed that pIgR−/− mice were profoundly more sensitive to infection with Salmonella typhimurium via the fecal-oral route, and that bacteria excreted from pIgR−/− mice after S. typhimurium infection were more contagious for other mice [84], as the composition of the excreted bacterial population may differ between pIgR−/− and WT mice.