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  • Author or Editor: Stacy V. Tessaro x
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Abstract

Objective—To determine whether cattle can become persistently infected with Brucella suis biovar 4, whether the organism can be transmitted vertically or horizontally, and whether tests for bovine brucellosis are diagnostic.

Design—Observational study.

Animals—24 pregnant cows and their calves and 6 bulls.

Procedure—Cows and bulls were housed separately in groups of 6 with each group consisting of 3 cattle experimentally infected with B suis biovar 4 and 3 naïve animals. Cattle were observed for clinical signs daily; blood samples were collected weekly. Clotted blood from each sample was submitted for bacterial culture. Serum was tested with an indirect ELISA and the standard tube agglutination test (STAT), buffered plate agglutination test, brucellosis card test (BCT), and complement fixation test (CFT). Tissues collected at necropsy were submitted for bacterial culture and histologic examination.

Results—All 15 inoculated cattle seroconverted on 2 or more serologic tests, and bacteria were isolated from 4 inoculated cows at necropsy. There was no bacteriologic evidence of vertical or horizontal transmission, and none of the cattle developed clinical abnormalities or gross or histologic lesions. Results of the indirect ELISA were positive for all inoculated cattle. The other tests gave variable results; the CFT, STAT, and BCT yielded negative results for at least 1 of the 4 cattle from which the organism was isolated.

Conclusions and Clinical Relevance—Results suggest that cattle-to-cattle transmission of B suis biovar 4 is unlikely. Serologic tests for bovine brucellosis should be used cautiously when attempting to identify cattle with rangiferine brucellosis, as they do not discriminate between the 2 diseases and vary in their ability to detect exposed cattle. (J Am Vet Med Assoc 2003;222:1252–1256)

Full access
in Journal of the American Veterinary Medical Association

Summary

Sixteen reindeer (Rangifer tarandus tarandus) naturally infected with Brucella suis biovar 4 were penned with 6 male and 2 female cattle for 30 days, then removed and euthanatized. During this period, 5 reindeer had fawns, and 2 reindeer aborted. Brucella suis biovar 4 was recovered from all adult reindeer at necropsy. Nine reindeer had B suis biovar 4 in uterus, udder, and/or milk. The cattle were euthanatized 2 months after the reindeer were removed. Clinical or pathologic signs of disease were not observed in the cattle. Brucella suis biovar 4 was isolated from 2 male and from both female cattle at necropsy. The female cattle had positive reactions on the buffered plate antigen test, brucellosis card test, tube agglutination test, complement fixation test, and indirect enzyme immunoassay for most of the experiment, but the males had inconsistent reactions on these tests. The indirect enzyme immunoassay was the only test to detect all cattle from which bacteria were cultured. This study revealed that caution is warranted before moving reindeer or caribou into areas of traditional agriculture.

Free access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine whether a herpesvirus isolated from the semen of a North American elk was related to bovine herpesvirus 1 (BHV-1).

Sample Population—Semen from 1 healthy bull elk and 2 subtypes of BHV-1 (BHV-1.1 and BHV-1.2).

Procedures—A virus with cytopathic and electron microscopic characteristics consistent with an alphaherpesvirus was isolated from elk semen, using fetal bovine kidney cells. Cross-neutralization assays were performed with antisera against BHV-1 and the elk herpesvirus (ElkHV). Restriction endonuclease digests of ElkHV DNA were compared with digests of BHV-1.1 and BHV-1.2 DNA. A portion of the ElkHV DNA polymerase gene was amplified with consensus primers by use of the polymerase chain reaction and sequenced. Sequence was compared with known sequences of other herpesviruses. An immunoperoxidase monolayer assay was used to determine reactivities of 22 BHV–1-specific monoclonal antibodies (mAb) against ElkHV. In vitro neutralizing activities of the reactive mAb were determined by use of a microneutralization assay.

Results—Results of cross-neutralization assays indicated that ElkHV was serologically related to BHV-1. Endonuclease digestion of ElkHV DNA generated fragments that were distinct from those of BHV-1. Nucleotide sequencing confirmed that ElkHV is an alphaherpesvirus closely related to but distinct from BHV-1. Six of 22 BHV–1-specific mAb reacted against ElkHV; 2 of these 6 also neutralized in vitro infectivity of ElkHV.

Conclusions and Clinical Relevance—ElkHV is antigenically and genetically distinguishable from BHV-1. However, the viruses are serologically related and share at least 6 antigenic determinants, one of which is a major neutralizing determinant. (Am J Vet Res 2000;61:1614–1618)

Full access
in American Journal of Veterinary Research