MX2 gene mRNA expression as potential biomarker for early pregnancy diagnosis in cattle

Early pregnancy diagnosis is vital for economic sustainability of dairy farms and maintaining the reproductive efficiency of the herd. There are many techniques including progesterone assay, pregnancy specific proteins and interferon stimulated genes have been explored for early pregnancy diagnosis but, they are associated with varying level of efficacy. In the present experiment, interferon stimulated gene (Myxovirus resistance gene 2/MX2) expression pattern was used as a potential biomarker for early pregnancy in cattle. The association of MX2 gene expression in relation to progesterone assay was studied to explore its potential use as biomarker of early pregnancy. The plasma progesterone concentration in conceived animals on day 7 (2.26±0.19 ng/ml), 17 (5.42±0.35 ng/ml) and 21(6.38±0.39 ng/ml) was recorded to be significantly higher as compared to respective values in non-conceived animals, i.e. 1.55±0.09 ng/ml, 4.14±0.14 ng/ml and 0.81±0.06 ng/ml. The sudden decrement in plasma progesterone concentration after day 17th discriminates conceived and non-conceived animals. MX2 expression levels were observed to spike in blood due to release of interferon tau (τ) after implantation of embryo. The relative mRNA expression of MX2 gene showed a 9.5 to 28.64-fold higher expression on 17 days post insemination in pregnant animals as compared to non-pregnant animals. Thus, MX2 gene can be used as a reliable biomarker for the early detection of pregnancy.