Molecular characterization of IFN-T expressed in buffalo embryonic trophoblasts and expression of recombinant BuIFN-T1a2 and BuIFN-T8 isoforms in E. coli.

Interferon tau (IFN-T) acts as a signaling molecule for maternal recognition of pregnancy (MRP) in ruminants. Aim of the present study was to identify various Buffalo Interferon tau (BuIFN-T) transcripts in buffalo trophoblast, phylogenetic comparison of these sequences with known mRNA sequences of buffalo, bovine, caprine and ovine and to express and purify the recombinant BuIFN-T (rBuIFN-T) isoforms. Following RNA extraction from trophectodermal cells, RT-PCR was performed using Ifn-t gene specific primers. 13 distinct cDNA variants encoding eight different BuIFN-T proteins were identified. BuIFN-T1a2 and BuIFN-T8 were expressed in prokaryotic expression system at 37 °C, 25 °C and 16 °C with 1 mM IPTG for 12 h and the recombinant proteins expressed at 16 °C were partially purified by Immobilised Metal Affinity Chromatography (IMAC). BuIFN-T isoforms have greater nucleotide and amino acid homology with caprine (98-100%, 96-100%), ovine (94-97%, 90-95%) and bovine (89.6-90.6%, 82-86%). These novel BuIFN-T isoforms contained pronounced nucleotide and amino acid sequence identity with one another (99.1-99.8%, 98-99%) but moderate sequence identity with previously identified buffalo IFN-T (90-92%, 82-86%). Solubility of expressed recombinant isoforms (rBuIFN-T1a2 and rBuIFN-T8) was highest at 16 °C. In conclusion, 13 distinct Ifn-t gene variants exist in trophectoderm of in vitro developed buffalo blastocysts that encode eight different proteins. rBuIFN-T1a2 and rBuIFN-T8 were successfully expressed in soluble form in Escherichia coli expression system at 16 °C with 1 mM IPTG and the resulting recombinant proteins were partially purified by IMAC.