Fcγ receptors are crucial for the expression of acquired resistance to virulent Salmonella enterica serovar Typhimurium in vivo but are not required for the induction of humoral or T-cell-mediated immunity.

Antibodies play an important role in immunity to Salmonella enterica. Here we evaluated the requirement for Fcγ receptors in host resistance to S. enterica using an in vivo model of systemic infection. We show that mice lacking FcγRI, II and III can control and clear a primary infection with S. enterica micro-organisms of low virulence, but are impaired in the expression of vaccine-induced acquired immunity to oral challenge with virulent bacteria. We also show that, in vivo, FcγRI, II, III^−/− mice were able to mount efficient T-helper 1 type T-cell responses and antibody responses specific for S. enterica. The work indicates that targeting S. enterica to FcγR is needed for the expression of vaccine-induced acquired immunity, but is not essential for the engenderment of T- and B-cell immunity to the bacterium in vivo. [ABSTRACT FROM AUTHOR]