Green J C, Volkmann D H, Poock S E, McGrath M F, Ehrhardt M, Moseley A E, Lucy M C
Division of Animal Sciences, University of Missouri, Columbia, Missouri 65211, USA.
J Dairy Sci. 2009 Aug;92(8):3819-24. doi: 10.3168/jds.2009-2120.
The ruminant trophoblast produces pregnancy-associated glycoproteins (PAG) that can be detected in the blood of pregnant animals. The objective was to determine the accuracy of a rapid ELISA PAG-based test for the purpose of pregnancy detection in cattle. Blood was sampled from dairy cattle (539 Holstein cows, 173 Holstein heifers, 73 Guernsey cows, 22 Guernsey heifers, and 12 Jersey heifers) and crossbred beef cattle (145 cows and 46 heifers) that were >or=25 d after insemination (range = 25 to 45 d for dairy and 29 to 56 d for beef). Cattle were examined by ultrasonography for detection of pregnancy within 2 d of blood collection. Whole blood or plasma was incubated in a polystyrene tube coated with a monoclonal PAG antibody for 15 min. The tubes were then washed and subjected to sequential incubations with a biotinylated polyclonal PAG antibody (15 min, followed by wash), a horseradish peroxidase-streptavidin solution (15 min, followed by wash), and a peroxidase substrate. Tubes were visually assessed for color after 15 min (clear solution = PAG negative, not pregnant; blue solution = PAG positive, pregnant). Total assay time was approximately 90 min. The ultrasound examination was used as the standard for pregnancy diagnosis. The sensitivity (99.8 +/- 0.2%), specificity (91.7 +/- 1.4%), and negative predictive value (99.7 +/- 0.3%) for the PAG test used in dairy cattle were similar for different breeds and for cows and heifers. The positive predictive value for the test was greater in dairy heifers than in dairy cows (96.5 +/- 1.4% vs. 90.5 +/- 1.7%, respectively). In beef cattle, the sensitivity (100%), specificity (92.3 +/- 3.0%), positive predictive value (95.0 +/- 2.0%), and negative predictive value (100%) for the PAG test were similar for cows and heifers. The accuracy of the test was not different for dairy and beef cattle. In conclusion, the rapid ELISA pregnancy test based on PAG was highly sensitive and specific for pregnancy detection in dairy and beef cattle.
反刍动物的滋养层会产生妊娠相关糖蛋白（PAG），这种蛋白可在怀孕动物的血液中检测到。本研究的目的是确定一种基于PAG的快速ELISA检测方法用于牛妊娠检测的准确性。从授精后≥25天的奶牛（539头荷斯坦奶牛、173头荷斯坦小母牛、73头根西奶牛、22头根西小母牛和12头泽西小母牛）和杂交肉牛（145头母牛和46头小母牛）采集血液（奶牛的采集范围为25至45天，肉牛为29至56天）。在采血后2天内通过超声检查牛是否妊娠。将全血或血浆在涂有单克隆PAG抗体的聚苯乙烯管中孵育15分钟。然后洗涤试管，并依次与生物素化多克隆PAG抗体孵育（15分钟，随后洗涤）、辣根过氧化物酶 - 链霉亲和素溶液孵育（15分钟，随后洗涤）以及过氧化物酶底物孵育。15分钟后通过肉眼观察试管颜色（溶液清澈 = PAG阴性，未怀孕；溶液呈蓝色 = PAG阳性，怀孕）。总检测时间约为90分钟。超声检查用作妊娠诊断的标准。用于奶牛的PAG检测的敏感性（99.8±0.2%）、特异性（91.7±1.4%）和阴性预测值（99.7±0.3%）在不同品种以及母牛和小母牛之间相似。该检测的阳性预测值在奶牛小母牛中高于奶牛（分别为96.5±1.4%和90.5±1.7%）。在肉牛中，PAG检测的敏感性（100%）、特异性（92.3±3.0%）、阳性预测值（95.0±2.0%）和阴性预测值（100%）在母牛和小母牛之间相似。该检测在奶牛和肉牛中的准确性没有差异。总之，基于PAG的快速ELISA妊娠检测方法在奶牛和肉牛的妊娠检测中具有高度敏感性和特异性。
