Vaccination of chickens with Salmonella Pathogenicity Island (SPI) 1 and SPI2 defective mutants of Salmonella enterica serovar Enteritidis

► Lohmann Brown and ISA Brown chickens respond differently to Salmonella Enteritidis infection. ► When vaccinated, both lines are equally protected against S. Enteritidis challenge. ► Vaccination with the SPI1 mutant was more effective than with the SPI2 mutant.