Interferon-Stimulated Gene Expression in Peripheral Blood Leucocytes as a Convenient Prediction Marker for Embryo Status in Embryo-Transferred Japanese Black Cows during the Peri-Implantation Period

SIMPLE SUMMARY: Practically and economically, predicting pregnancy status is crucial for food animal production. Recently, the expression of interferon-stimulated genes (ISGs) in peripheral blood leukocytes has been examined as a biomarker for predicting the gestational status during maternal recognition in ruminants. Although the ISG levels in the blood cells of cattle have been reported, the practical application of this detection method in embryo-transferred (ET) cows has not been evaluated in detail. The levels of three of the four ISGs in this study were significantly higher in pregnant cows than in non-pregnant cows on day 21 of gestation. The diagnostic performance results showed that the three ISGs are appropriate biomarkers for predicting the gestational status of ET cows. The statistical evaluation of diagnostic accuracy in ET cows indicated that the values of sensitivity, specificity, and accuracy were very high and the positive predictive values of the three ISGs were estimated. The results of this study suggest that ISGs are good biomarkers for gestational status during the peri-implantation period in ET cattle. ABSTRACT: Pregnancy diagnosis during early gestation is important for cattle reproduction. The expression of interferon-stimulated genes (ISGs) in peripheral blood leukocytes (PBLs) was studied in embryo-transferred (ET) Japanese Black cattle. ISGs in PBLs—ISG15, MX1, MX2, and OAS1—were detected in multiple ovulation ET cattle using a real-time quantitative polymerase chain reaction, and receiver operating characteristic (ROC) curve analysis was performed. Gestational status was predicted using the average ISG levels during the normal estrous cycle (AVE) and the Youden index from the ROC curve analysis as cutoff values. The ISG15, MX1, and MX2 levels were significantly higher in pregnant cattle (n = 10) than in non-pregnant cattle (n = 23) on gestation day 21, whereas the levels of all ISGs were similar between non-pregnant and non-pregnant cattle with late embryonic death (n = 7). ISG15, MX1, and MX2 appropriately predicted the gestational status of ET cows. The statistical evaluation of the diagnostic accuracy in ET cows on day 21 of gestation presented higher values of sensitivity, specificity, accuracy, and positive predictive values of ISG15, MX1, and MX2 using the Youden index than using the AVE. Therefore, ISG15, MX1, and MX2 are excellent biomarkers of gestational status during the peri-implantation period in ET cattle.