Efficacy of Salmonella enteritidis-immune lymphokines on horizontal transmission of S. arizonae in turkeys and S. gallinarum in chickens

Abstract

Salmonella arizonae ( SA) and S. gallinarum ( SG) are of economic importance to international poultry production because of their pathogenesis in young poultry during the first week after hatching. Previous studies from our laboratory have shown immune lymphokines (ILK) produced by S. enteritidis ( SE)-immunized chickens provide protection against SE organ invasion in day-old chickens and turkey poults. Previous studies have also demonstrated that SG organ invasion was significantly decreased by administration of ILK to broiler chicks. The objective of the present study was to determine the effect of ILK on the incidence of horizontal transmission of SA in turkey poults and of SG in broiler chicks. The effect of ILK administration on horizontal transmission of SA in poults and SG in chicks was assessed in a seeder/contact model. Seeders were challenged with the appropriate bacterium ( SA turkeys, SG chicks), contacts were either untreated or administered ILK. Seeders and contacts cohabited within an experimental group throughout the experiment. Mortality and organ invasion as a result of horizontal transmission were determined. There were no significant differences in mortality between non-treated and ILK-treated contact poults. In contrast, SG was extremely pathogenic to young broiler chicks. Non-treated contact chicks had a mortality rate of approximately 68% whereas significant ( P<0.05) reduction in mortality was demonstrated in the contact chicks treated with ILK (15%). Horizontal transmission, as determined by organ invasion, of SA to contact turkey poults and SG to contact broiler chicks was also significantly ( P<0.05) decreased by immunoprophylactic administration of ILK. Bacterial recovery of SA from the liver/spleen and the cecal tonsil in contact poults and SG from contact chicks treated with ILK was dramatically reduced when compared to non-treated contact poults and chicks. Our results strongly suggest the immunoprophylactic administration of SE-immune lymphokines to young turkey poults and broiler chicks significantly reduces the horizontal transmission of Salmonella in poultry. These results suggest the possibilities of using a non-vaccine immunologically-based preventative strategy against Salmonella in poultry.