Review of the Food-borne Zoonoses Research ... - ARCHIVE: Defra

Project code: OZ0313
Project title: Non-specific and innate resistance to Salmonella
infection in chickens and pigs
Start date (dd/mm/yy): 01/04/99
End date (dd/mm/yy): 30/06/02
£689,400
Total cost:
Affiliation: Institute for Animal Health
Abstract of research
We have studied the biological and cellular basis of the difference in in vivo killing of
Salmonella strain by chicken lines which are either resistant or susceptible to systemic
salmonellosis. Resistance correlated with killing by macrophages cultured in vitro from
the blood of the respective chicken lines. This also correlated with the extent to which
antibacterial oxidative radicals were produced in response to in vitro infection. This is a
useful biological marker of this important genetic trait.
Infection of epithelial cells by different Salmonella serovars provoked different responses.
S. Typhimurium induced high levels of the pro-inflammatory chemokines IL-1 and IL-6
whereas S. Gallinarum was able to suppress their production. The suppressive
capabilities of Salmonella strains was also demonstrated by virulent strains of S.
Typhimurium in murine macrophages which were able to down-regulate the production of
nitric oxide through the NF kappa B pathway. The induction of innate responses by live
vaccines and their protective ability has been demonstrated in gnotobiotic pigs which has
been found to be mediated by the induction of IL-8 induced neutrophils into the villus.
The stimulation of the innate response by live vaccines is a useful attribute. We have
also found the neutrophils have the potential to act as antigen presenting cells through
the expression of the B17 co stimulatory molecule.
Review Summary
The project was appropriate at the time it was commissioned. It was carried out to a high
standard and produced interesting results. It has considerably advanced the
understanding of some of the fundamental mechanisms for establishment and clearance
of salmonella infections in chickens and pigs. The goals of the research, namely 1) to
determine the cellular basis for the difference in susceptibility to systemic salmonellosis
in inbred chicken lines, and 2) to determine the basis for the stimulation of non-specific
immunity in the pig intestine following intestinal colonisation by an avirulent rough
Salmonella Infantis strain, have been achieved.
The pig work demonstrated effective activation of innate immune response by one
serotype (S. Infantis) to protect from disease induced by another serotype (S.
Typhimurium). However, this protection did not reduce the colonisation of the intestine
so, as in the chicken work, it is more relevant to control of animal disease than to the
zoonoses.
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