Expression and molecular cloning of interferon stimulated genes in buffalo (Bubalus bubalis)

Abstract

Buffalo, the most important livestock species in tropical India, remains to be a poor breeder mainly due to embryonic mortality (65%) occurring mostly between 16 and 18 days of pregnancy. Early and accurate diagnosis of pregnancy can thus become a boon for successful herd management in buffalo. However, most of the currently available methods allow diagnosis only after 30 days post AI. Interferon tau (IFNT), the first pregnancy recognition signal in ruminants is one such molecule, which stimulates expression of various Interferon stimulated genes (ISGs) in the peripheral blood mononuclear cells (PBMC's) concomitant with IFNT signaling which occurs around maternal recognition of pregnancy (MRP). Hence, the study was planned to demonstrate the expression dynamics of ISGs (OAS1, MX1, MX2 and ISG15) in PBMCs during peri-implantation period in buffalo and also molecular cloning and expression of suitable ISG coded protein (s) in suitable host. Blood was collected from two groups of multiparous buffaloes: Group1: (n = 10) inseminated/pregnant (Experimental) and Group2: (n = 10) anestrous/non pregnant (Control). The expression profile of ISGs was then analyzed using real time qPCR. Expression profile of most ISGs was observed to increase through day 14 to day 20 post AI and declined thereafter. On the basis of differential gene expression at day 18 post AI, OAS1 and MX2 were identified as suitable ISG candidate biomarkers for accurate pregnancy diagnosis within 18 days post AI. Molecular cloning and expression of selected ISGs in a suitable prokaryotic expression vector was done thereafter. Bulk expression of the recombinant proteins was done and purified by affinity chromatography and confirmed by Western blot using Mouse Monoclonal His-probe antibodies. To conclude, as OAS1 and MX2, showed distinct differential expression at day 18 post AI, they may serve as ideal biomarkers for detection of early pregnancy in buffalo.