Development of slide micro-agglutination system for the rapid diagnosis of Salmonella infection in the chicken

The cultural method to identify avian Salmonella infections is laborious and expensive, thus a rapid, sensitive and cost-effective method for the diagnosis of salmonellosis is anticipated. S. pullorum was isolated and a stained Salmonella somatic antigen was prepared. The protein concentration of stained antigen was measured and adjusted to 3000 ng/μl. Preservative was used to increase its shelf life. Slide agglutination tests were carried out with un-diluted and diluted anti-sera having known ELISA titre and end point agglutination titre was determined. The standard curves were generated using 2 and 10 fold dilutions of sera to determine the titre of the unknown field sera. It was observed that the newly developed stained somatic antigen produced distinct tiny clumps with positive anti-sera of Salmonella spp. The present slide agglutination system was found to be easy, sensitive, reliable, cost and time effective and needs very small amount of antigen, sera and as well as accessories. This method may be used to screen the Salmonella infections in the poultry farms and to calculate the titre of the antisalmonella antibody in the infected and vaccinated chickens under farm conditions. A test kit containing stained antigen along with positive and negative control sera may be prepared for commercial uses.