SPI1 and infection: However, some Salmonella lacking the T3SS-1 remain pathogenic in different in vivo infection models such as a SPI-1 mutant of S. Gallinarum in adult chicken (Jones et al., 2001) or S. Typhimurium and S. Enteritidis mutants in one week-old chicks or Balb/C mice (Coombes et al., 2005; Jones et al., 2007; Karasova et al., 2010).