title: Salmonella enterica serovar Pullorum requires the Salmonella pathogenicity island 2 type III secretion system for virulence and carriage in the chicken.
abstract: Functional mutations were made in the type III secretion systems encoded by Salmonella pathogenicity island 1 (SPI 1) and Salmonella pathogenicity island 2 (SPI 2) of Salmonella enterica serovar Pullorum, the cause of pullorum disease in poultry. Their role in cell invasion in vitro, and in virulence in vivo was determined. The SPI 1 mutant showed decreased invasiveness for chicken cells but was capable of causing disease in orally infected 1-day-old chicks, although it showed some reduction in virulence. The SPI 2 mutant showed no reduction in invasiveness, but was fully attenuated for virulence in 1-day-old chicks, and was not detected following oral infection in 1-week-old chickens. Following intravenous infection, the SPI 2 mutant was also attenuated and cleared more rapidly than the parent strain. This indicates that S. Pullorum requires SPI 2 for virulence and persistence but SPI 1 appears to contribute to, but is not essential for, the virulence of S. Pullorum.
authors.affiliation: Institute for Animal Health, Compton Laboratory, Compton, Newbury RG20 7NN, UK. paul.wigley@bbsrc.ac.uk
authors.forename: Paul
authors.initials: P
authors.lastname: Wigley
authors.forename: Michael A
authors.initials: MA
authors.lastname: Jones
authors.forename: Paul A
authors.initials: PA
authors.lastname: Barrow
mesh_terms: D000818:Animals; D002645:Chickens; D008099:Liver / Q000382:microbiology / Q000473:pathology; D011201:Poultry Diseases / Q000382:microbiology* / Q000635:transmission; D012475:Salmonella / Q000302:isolation & purification / Q000472:pathogenicity; D012481:Salmonella Infections, Animal / Q000473:pathology* / Q000635:transmission; D019779:Salmonella enterica / Q000472:pathogenicity*; D013154:Spleen / Q000382:microbiology / Q000473:pathology; D013997:Time Factors; D014774:Virulence