Chronological recognition by chicken of antigenic polypeptides in Salmonella Enteritidis with different plasmid profiles: Relationship to infection rate

The antigenic polypeptides in Salmonella Enteritidis (SE) were chronologica lly recognized by the chicken immune system, using Western immunoblotting. Broiler chicks challenged at three days of age with SE strain carrying the most prevalent plasmid profile of 14.1 and about (similar to) 50 kb were bl ed at 17, 24, 31, 38 and 45 days of age. Pooled sera of blood collected at each age was reacted by Western immunoblotting with banded polypeptides of three predominant SE strains that acquired the following respective plasmid profiles: 14.1 kb; 14.1 and similar to 50.0 kb; and 1.8, 14.1 and similar to 50.0 kb. The immunoblots of each pooled sera collected at a specific age against the three SE strains were similar. More specifically, the early im mune response at 17 days of age had antibodies recognizing only one polypep tide in the three SE strains namely, the 35.8 kDa. At 24 or 31 days of age, the acquired immunity to infection had antibodies recognizing five similar polypeptides in the three SE strains namely, the 14.4 (fimbriae protein), 21.5 (fimbriae protein), 30.5, 35.8, and 66.2 kDa. At 38 and 45 days of age , the antibodies recognized additional polypeptides namely, the 41.5 and 55 .6 kDa, respectively. The recognition of the 41.5 and 55.6 kDa polypeptides at 45 days of age was associated with higher invasiveness of SE to spleens and livers (15.6%) and in higher cecal colonization (59.4%) in comparison to absence of recognition to the two polypeptides at 31 days of age associa ted with low infectivity to spleens (0%), livers (3.1%), and ceca (9.4%).