The subject is the attempt to produce reliable detection of antibodies in the colostrum to facilitate ease of sample collection by herdsmen. These samples could be frozen. The study in the article indicated that antibody to OPP virus was detectable in colostrum with the AGID test

Schipper, I.A.

Vadheim, Kirsten L.

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DETECTION OF COLOSTRAL ANTIBODIES TO OVINE PROGRESSIVE PNEUMONIA VIRUS Kirsten L. Vadheim and I. A. Schipper I n most laboratories, antibodies to ovine progressive pneumonia virus are detected in serum samples with the agar gel immunodiffusion (AGID) test. We compared AGID results on matched serum and colostrum samples from 102 ewes. Our findings indicate that colostrum samples may provide a screening tool as reliable as serum. Furthermore, colostrum does not require the equipment or bleeding skills necessary when working with serum samples. Ovine progressive pneumonia (OPP) is a chronic, fatal disease affecting 30 to 70 percent of midwestern and western sheep (3). The causative agent is a slow virus similar to a number of other viruses in many parts of the world. Because signs develop gradually over a period of years, a large number of sheep may be af­fected before the disease is diagnosed (2, 4). Flocks are currently screened for the presence of specific anti­bodies to OPP virus by the agar gel immunodiffusion (AGID) test on serum. If antibodies could be detected reliably in the colostrum, sample collection for screen­ing could be done easily by herdsmen and samples could be frozen. Our results indicate that antibody to OPP virus is detectable in colostrum with the AGID test. MATERIALS AND METHODS Colostrum was obtained within 6 hours of lambing from 102 ewes in two separate flocks. Five milliliters of thawed or fresh colostrum was combined with 0.1 milliliter of rennin and allowed to incubate at 37°C for I hour. The whey was removed and stored at 4°C. Vadheim is graduate research assistant and Schipper is professor, Department of Veterinary Science. Funding of this project was by USDA Special Grant No. 59-2381-1-2-069-0. The authors are grateful to Professor M. Light, Department of Animal Science, for providing the sheep used in this investigation and to W. Lime­sand, shepherd, Animal Science for his help in sample collection. AGID slides were prepared by coating glass slides with an adhesive agar and overlaying with 2.5 milliliters of 1.5 percent IS Ionager. The agar was allowed to solidify and was then set in a humidity chamber for 1 hour at room temperature. Wells were cut in the agar in a pattern of six peripheral wells surrounding one central well. Twenty­seven microliters of OPP viral antigen was added to the central well. The peripheral wells were filled alternately with either calcium magnesium-free phosphate buffered saline or a known positive sample as negative and positive controls. On experimental slides, serum and colostrum samples to be tested were substituted for the negative controls. The slides were then incubated in a humidity chamber at room temperature for five days. Results were read while observing the slides over an indirect light source. Positive samples indicated by the formation of precipitin lines midway between the central and sample wells. RESULTS Table 1 indicates the results of AGID screening for OPP virus antibodies in flocks I and 2. Samples from flock 2 were taken only from ewes previously determin­ed to be OPP-positive by AGID on serum. TABLE 1 Flock 1 Flock 2 Sheep Colostrum Serum Sheep Colosrum Serum Red 13 533 + + 14 9226 + + 15 8476 + + 50 9198 + + 53 0273 + + Blue 2 + + 80-633 + + 7 80-209 + + 19 8702 + + 21 + + 9·152 + + 23 194 + + 24 8317 + + 25 7068 + + Orng2 8034 + + 3 + + 2099 + + 5 + + 80·028 + + 6 9·281 + + 8 V·42 + + 9 77-103 + + 11 2013 + + 14 + + 9516 + + 16 8701 + + 26 Flock 1 Flock 2 tibodies formed against OPP virus in the serum might Sheep Colostrum Serum Sheep Colosrum Serum be expected in the colostrum. Orng 17 + + 1362 + + 25 + + 81-13 + + The disparity in the results for sheep 40, Flock 1 26 77-464 + + 29 80-098 + + (which gave negative results with serum and positive 40 + 80-194 + + results with colostrum) may have been due to the length 41 77-396 + + of time which passed between serum and colostrum col­42 9147 + + 43 0382 + + lection. During the weeks or months involved, the titer 44 81-109 + +  may have decreased significantly in the serum. It is also45 7181 + + 46 1629 + + possible that since IgG is more concentrated in the col­47 P421 + + ostrum than in the serum, weak positives would be more 77-069 +48 + likely to appear in the colostrum samples. 49 9052 + + 50 7188 + + Gr 1 205 + + Our results show that AGIO testing on colostrum 4 7137 + + samples is a reliable method for screening for the11 + + 7388 + + 15 81-391 + + presence of OPP virus antibodies. 21 131 + + 22 F80 + + 148 + + 9137 + + 239 + +  REFERENCES119 + + 81-623 + + J. Cutlip, R. C., T. A_ Jackson, G_ A. Laird. Immunodiffusion 375 + + 78-304 + + test for ovine progressive pneumonia. Am. J. Vet. Res. 38: 81-706 + + 1081-1084,1977_ 846] + + 30099 + + 2. Cutlip, R. c., G. A. Laird. Isolation and characterization of a No Tag + + virus associated with progressive pneumonia (maedi) of sheep.5-027 + + Am_ J. Vet. Res. 37:1377-1382, 1976_0129 + + 1362 + + 79-281 + + 3. Cutlip, R_ c., T. A. Jackson, G. A. Laird. Prevalence of ovine 8640 + + progressive pneumonia in a sampling of cull sheep from T161 + + western and midwestern United States. Am. J. Vet. Res_ 8188 + + 38:2091-2093, 1977. 4. Mohanty, S. B., S. K. Dutta: Veterinary Virology. Lea and Febinger, Philadelphia, 198 J. The near-perfect correlation between serum and col­5. Moliter, T. W., I. A. Schipper, D. L. Berryhill, M. R. Light.ostrum samples on antibody screening is not surprising Evaluation of the agar gel immunodiffusion test for the detec­in light of the humoral immune mechanisms involved in tion of precipitating antibodies against progressive pneumonia ruminant colostrum. Immunoglobulin G (IgG) , the virus of sheep. Can. J. Compo Med. 43:280-287, 1979. primary immunoglobulin in sheep colostrum, is entirely 6. Newby, T. J., C. R. Stokes, F. J. Bourne. Immunological ac­serum derived and is found in much higher concentra­tivities of milk. Vet. Immun. Immunopath. 3:67-94, 1981. tions in the colostrum than in the serum. Therefore an­27 

Detection of Colostral Antibodies to Ovine Progressive Pneumonia Virus

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