Preliminary evidence for a diagnostic immunoglobulin G1 antibody response among culture-positive cows vaccinated with Brucella abortus strain 19 and challenge exposed with strain 2308.

The sera of cows inoculated with Brucella abortus have a characteristically high titer of immunoglobulin (Ig) G1 antibodies to a soluble brucella antigen compared with sera of noninoculated vaccinated cattle. Concentrations of antigen-specific IgG1 were greater than 10-fold higher than those for IgG2, even though total IgG2 concentrations were higher than total IgG1 concentrations. Increases in IgG1 antibodies to Brucella abortus soluble antigen were detected shortly after vaccination in those cows from which strain 19 was isolated and by 28 weeks in cows from which strain 2308 was isolated.

Enzyme immunoassay for swine trichinellosis using antigens purified by immunoaffinity chromatography.

Various preparations of crude and a purified preparation of Trichinella spiralis antigens were compared in a rapid, micro-enzyme immunoassay (EIA) for detecting trichinellosis in swine. The crude antigen preparations (XM-300 or S3 fraction) were lipid-free, cell-free fractions of muscle larvae, and the purified antigen was prepared by immunoaffinity chromatography of the soluble fraction of stichocyte secretory granules from rat muscle larvae. The antigens were tested against normal and immune swine sera for sensitivity and specificity, and for their ability to detect seroconversions early in the immune response.

Automation of the enzyme immunoassay for the serodiagnosis of infectious diseases in livestock.

The enzyme immunoassay is a highly versatile diagnostic tool whose use is rapidly spreading throughout the world. With the number of reagents, processing steps and possible protocols involved, and the growing list of devices used to automate or semiautomate the test, there is an immediate need to develop standard procedures for evaluating test performance and making diagnostic decisions. The positive and negative reference sera against which test samples are compared must be carefully selected and evaluated to insure that they are representative of field populations.

Comparisons of some bluetongue virus isolates by plaque neutralization and relatedness tests.

Seven North American bluetongue virus isolates, cloned by plaquing, and sera to five of them were reacted in a plaque neutralization test. Using a paired controls system, each virus-serum reaction was studied in terms of the regression of percent neutralization on log serum dilution. Antigen-antibody interaction terms in the analysis of effective dose estimates were used to assess the relatedness of the virus isolates.