Effect of inv mutations on Salmonella virulence and colonization in 1-day-old White Leghorn chicks.

Invasion of Salmonella into the cells of the intestinal epithelium is an important step in the infection process. This initial invasion is followed by colonization of other organs throughout the body. In an attempt to better understand this process, we moved defined mutations in several genes of the inv locus into Salmonella typhimurium UK-1 and two strains of Salmonella enteritidis. These mutant strains were evaluated for their oral and intraperitoneal virulence as determined by 50% lethal dose in 1-day-old white leghorn chicks. These inv mutants were also studied for their ability to colonize orally infected chicks. The invA, invB, and invC mutations all caused a reduction in oral virulence and colonization by UK-1 and the S. enteritidis strains. Mutation of the invH gene had little or no effect on oral virulence or colonization. None of the inv genes tested had any effect on virulence of these Salmonella strains when administered intraperitoneally.