title: Presumptive diagnosis of subclinical infections utilizing computer-assisted analysis of sequential enzyme-linked immunosorbent assays against multiple antigens.
abstract: One-hundred-seventy-two serum samples, collected sequentially from four flocks of egg- and meat-type chickens, were evaluated for antibodies to multiple infectious agents by enzyme-linked immunosorbent assay (MELISA). The MELISA system used provided simultaneous measurement of antibody titers against avian infectious bronchitis (IB), infectious bursal disease (BD), Newcastle disease, avian encephalomyelitis and reovirus infections, and Mycoplasma gallisepticum. The use of computer-generated graphic print outs of relative MELISA titers provided immediate visulization of over 740 data points and convenient detection of any temporal changes in median titer class (MTC). The temporally changing MTC, or flock profiles obtained, indicated that negligible or waning IB immunity may be a common occurrence in previously vaccinated commercial chickens. These profiles further suggested that, despite no IB revaccination, these same flocks experienced episodes of reexposure to IB which otherwise may have been difficult to detect by conventional clinical or diagnostic laboratory protocols. MELISA profiles and sequential histologic examinations of bursas of Fabricius also provided evidence of a possible BD vaccination problem in young chickens that also experienced excessive losses from coccidiosis, ulcerative enteritis, and Marek's disease. Short sampling intervals were found to foster the detection and definition of fluctuations in MTC which otherwise may have been missed.
mesh_terms: D000818:Animals; D000942:Antigens, Bacterial / Q000032:analysis*; D000956:Antigens, Viral / Q000032:analysis*; D001424:Bacterial Infections / Q000175:diagnosis / Q000662:veterinary*; D002645:Chickens; D003201:Computers; D004797:Enzyme-Linked Immunosorbent Assay; D011201:Poultry Diseases / Q000175:diagnosis*; D014777:Virus Diseases / Q000175:diagnosis / Q000662:veterinary*
chemical_list: D000942:Antigens, Bacterial; D000956:Antigens, Viral