Susceptibility of calves to challenge with Salmonella typhimurium 4/74 and derivatives harbouring mutations in htrA or purE

Abstract

Salmonella typhimurium 4/74 is highly virulent for cattle after oral challenge, causing severe diarrhoea, which is sometimes associated with systemic spread of the micro-organism. Although susceptible to oral challenge, groups of cattle were found to be relatively resistant to subcutaneous challenge with this strain. The virulence of S. typhimurium 4/74 harbouring mutations in htrA and purE was also assessed in cattle. Although S. typhimurium 4/74 htrA and purE are attenuated following oral challenge in mice, cattle were highly susceptible to oral challenge with these mutants. As with the parent S. typhimurium 4/74 strain, cattle exhibited greater susceptibility to oral compared to subcutaneous challenge with S. typhimurium htrA and purE mutants. Following subcutaneous challenge with sublethal levels of S. typhimurium 4/74, calves produced significant levels of antibodies to S. typhimurium soluble extract. No correlation was detected between interferon gamma levels in sera and susceptibility to infection by any route. The concentrations of the acute-phaseassociated protein haptoglobin were increased in the sera of five of six cattle inoculated subcutaneously, although increases in concentration were smaller in cattle inoculated orally.

Susceptibility of germ-free pigs to challenge with protease mutants of Salmonella enterica serovar Typhimurium

“…Infected pigs suffered symptoms of endotoxin shock as did gnotobiotic pigs infected with LT2 wild type strain and they contained essentially the same numbers of bacteria in circulation. A similar course of the disease was observed also in conventional calves infected orally with htrA mutant of S. Typhimurium (Villarreal-Ramos et al, 2000).…”

Developing a 3D intestinal epithelium model for livestock species

“…S. typhimurium 4/74 strain was chosen for infection as it is an enteric bacterium that is highly virulent in cattle after oral challenge (Villarreal-Ramos et al 2000 ). There is no published evidence that mice are susceptible to challenge with this bacteria thus mouse organoids were utilised as a control.…”

A Comparison of Acute Phase Protein Measurements and Meat Inspection Findings in Cattle

“…It is of interest that the only groups not showing significant difference were the SAA concentration when compared between the healthy and cows with non-acute conditions. As mentioned above it is possible that the 'healthy' cows were suffering from sub-clinical conditions and SAA is known to be more sensitive than haptoglobin in that it has been found to give low responses to mild stimulation where the haptoglobin is not elevated (Villarreal- Ramos et al, 2000).…”