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in Journal of the American Veterinary Medical Association

Objective

To monitor the prevailing viral respiratory tract infections in cattle after transportation to feedlots.

Animals

100 cattle with signs of respiratory tract disease on arrival at 2 feedlots.

Procedures

Nasal swab samples were obtained from each animal and were used for inoculation of defined cell culture systems that detected bovine viruses known to cause respiratory tract infections, as well as viruses previously not recognized as respiratory pathogens for cattle.

Results

Bovine respiratory coronaviruses were isolated from 38 of the 100 cattle, including 6 of 50 cattle from California, 22 of 31 cattle from Oklahoma, 6 of 11 cattle from Texas, and 4 of 8 cattle of unknown origin. Parainfluenza 3 viruses also were isolated from 4 California cattle, but other bovine viruses were not detected.

Clinical Implications

The high rate of coronavirus isolations from feedlot cattle with signs of respiratory tract disease implied wide distribution and high susceptibility among cattle to this infection, which had not been detected by use of viral isolation systems in previous etiologic evaluations of feedlot cattle affected with bovine respiratory disease complex. (J Am Vet Med Assoc 1996; 208:1452-1455)

Free access
in Journal of the American Veterinary Medical Association

Summary

Clinical trials have shown that currently available commercial vaccines against porcine pleuropneumonia provide inconsistent, serotype-specific protection from the disease. Recovery from naturally acquired infection, however, provides solid, serotype cross-protective immunity. We examined various serum responses of pigs receiving 1 of 4 commercial vaccines or a cell extract, and compared the serologic responses of these pigs after challenge exposure with virulent Actinobacillus pleuropneumoniae serotype 1. Evaluation of serum included complement-mediated killing, opsonizing capacity, IgG titers to whole organisms, and cytotoxin neutralization titers. Pigs that received the cell extract had fewer clinical signs of pleuropneumonia than pigs in other vaccinated groups, and also were significantly (P< 0.05) better protected from development of lung lesions and death. Such vaccinates were the only pigs that developed significant (P< 0.05) serum antibody titers (ie, protective immune response) to whole-cell antigens and to cytotoxin.

Free access
in American Journal of Veterinary Research

Summary

Viral rna oligonucleotide fingerprinting was used to discriminate 3 cytopathic vaccine bovine viral diarrhea viruses (bvdv) grown in medium supplemented with serum contaminated with noncytopathic bvdv from the same 3 viruses grown in cell culture free of bvdv. Oligonucleotide fingerprinting also effectively discriminated between reference Singer bvdv, nadl bvdv, and New York-1 bvdv grown in bvdv-free noncontaminated or bvdv-contaminated cell cultures. Oligonucleotide fingerprint mapping of viral rna maybe used to determine the purity of virus stocks, as well as that of bvdv vaccines.

Free access
in American Journal of Veterinary Research

Summary

Bovine viral diarrhea virus (bvdv) infections resulting in clinical disease developed in calves, despite vaccination of dams and high maternal bvdv antibody titers in calves. Eight persistently injected (pi) calves born to immunocompetent dams were identified in the herd. Neutralizing bvdv antibody titers of pi calves had decreased greatly by the time the calves were 1 to 2 months old. Antibody titers of pi calves decreased more rapidly than antibody titers of calves that were not pi. Reduced antibody titers in pi calves allowed detection of bvdv in serum specimens of all pi calves by the time they were 8 weeks old. Persistent infection in suspect calves was detectable serologically and was confirmed by virologic examination of serum specimens 4 months after weaning, when the calves were 9 months old. Growth rates were reduced in viremic calves.

Free access
in Journal of the American Veterinary Medical Association

SUMMARY

Viral rna oligonucleotide fingerprinting was used to compare genetic relationships among pestiviruses originating from ovine or bovine host species. Ovine pestiviruses, including reference border disease virus and 2 border disease isolates originating from natural pestivirus infections of sheep, appeared to have a more distant genetic relationship among themselves than with certain bovine pestiviruses. A closer genetic relatedness was evident between border disease virus and 3 noncytopathic bovine pestiviruses, including Draper bovine viral diarrhea virus (bvdv), a bvdv isolate that originated from aborted bovine fetuses, and a virus that was isolated from the serum of a calf that had a chronic bvdv infection. Four noncytopathic bovine viruses, including Draper bvdv and 3 field isolates, were closely related. Reference Oregon C24V bvdv, a cytopathic virus, was closely related to only 1 of the 7 noncytopathic viruses in this study.

Free access
in American Journal of Veterinary Research