Seven bovid herpesvirus-4 (BHV-4) isolates recovered from various clinical conditions of cattle were studied for their pathogenic potential in pregnant rabbits. These viruses were originally recovered from respiratory and reproductive tract infections of cattle. A virus dose of 4 × 106.8TCID50 per fetus was inoculated via the intrauterine route in 10- and 17-day pregnant rabbits. Clinical, virologic, and pathologic data were collected to compare the effect of each isolate on does and fetuses/kits. Three isolates (LVR-140, QVR-3140 and 86-068) caused abortion, fetal reabsorption and/or mummification in inoculated rabbits. Virus was recovered from tissues of inoculated rabbits (especially the spleen, ovaries and uterus) by organ explanation and/or co-cultivation. Intravenous inoculation of isolate 86-068 did not produce any clinical signs in either 10- or 17-day pregnant rabbits. All seven isolates of BHV-4 showed a predilection for the reproductive tract of pregnant rabbits but varied in the severity of disease signs produced. Variation was also observed in the genome of various isolates on the basis of restriction endonuclease (RE) analysis. Relationship of RE patterns to the variation in the pathogenic potential of seven BHV-4 isolates is discussed.
Bibliographical noteFunding Information:
We thank Drs. J.F. Evermann (Washington State University, Pullman, WA ), F.A. Osorio (University of Nebraska, Lincoln, NE ) and G. Wellemans (Institute for Veterinary Research, Groeselenberg, Belgium) for providing some of the BHV-4 isolates used in this study. Technical assistance of Chris Thurn and Dale Carlquist is gratefully acknowledged. Published as contribution no. 17,029 of the series of the Minnesota Agricultural Experiment Station. Funding for this project was provided by Minnesota Agricultural Experiment Station and the Pakistan Agricultural Research Council, Islamabad, Pakistan. Dr. Naeem is a fellow of the Pakistan Agricultural Research Council.