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  • Author or Editor: Arthur J. Davis x
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SUMMARY

We report here genetic recombination between 2 USDA-licensed vaccine strains of pseudorabies virus co-inoculated into swine. The vaccine strains, one of which was a conventionally attenuated strain and the other, a genetically engineered deleted strain containing a negative immunologic marker, had complementary genomes. Co-inoculation resulted in the creation of novel strains of pseudorabies virus containing negative immunologic markers with restored virulence genes. Plaque-purified recombinant progeny viruses were found in 2 litters of pigs in which both strains were co-inoculated im, a litter in which both strains were co-inoculated oronasally, and a litter in which the conventionally attenuated strain was inoculated oronasally and the genetically engineered strain was inoculated im. Recombinant phenotypes and recombinant restriction fragment patterns were observed. The creation, spread, and potential misdiagnosis of these types of recombinant strains could disrupt control and eradication programs that are based on the serologic identification of swine infected with potentially virulent strains of pseudorabies virus.

Free access
in American Journal of Veterinary Research

Abstract

A study to determine and compare the sensitivity of the caudal fold tuberculin test (cft) and a commercial γ-interferon (γ-ifn) assay for diagnosis of bovine tuberculosis was conducted. A dairy herd with approximately a third of the cattle infected with Mycobacterium bovis was chosen for this study. All cattle from this herd were slaughtered, and tissue specimens for bacteriologic culturing and histologic examination were collected. Results of the cft and γ-ifn assay were compared with results of bacteriologic culturing and histologic examination to determine test sensitivity. Results were analyzed, using each of the following 4 standards to classify cattle as infected: positive test result by bacteriologic culturing only; histologic examination only; bacteriologic culturing and histologic examination; and bacteriologic culturing or histologic examination. Sensitivity of the cft ranged from 80.4 to 84.4%, depending on the standard of comparison. Sensitivity of the γ-ifn assay ranged from 55.4 to 97.1%, depending on the standard of comparison and on the method of interpretation. The cft was significantly (P < 0.001) more sensitive than the γ-ifn assay for diagnosis of bovine tuberculosis when the γ-ifn assay was conducted and interpreted as instructed by the manufacturer. Maximum overall sensitivity was achieved when results of the cft and γ-ifn assay were interpreted in parallel.

Free access
in American Journal of Veterinary Research