A stable and potent buffalo EF1α1 promoter for robust gene expression in mammalian systems

This study reports the first isolation and characterization of the buffalo EF1α1 promoter, demonstrating its strong gene expression activity both in vitro across diverse cultured cell types and in vivo across multiple mouse organs. Although viral promoters, such as cytomegalovirus (CMV) and simian virus (SV40), are widely used for their strong expression in various cell lines in mammalian expression systems and in animal tissues, they are prone to methylation-induced transcriptional silencing and subsequent loss of exogenous gene expression. The most effective alternative to viral promoters is the synthetic hybrid CAG promoter (cytomegalovirus major immediate-early enhancer combined with the chicken beta-actin promoter) or mammalian cellular promoter such as human elongation factor 1 alpha (hEF1α), which drives strong gene expression but lacks consistency and is limited in their in vivo expression potential due to their vulnerability to epigenetic silencing. To overcome these challenges, the bbEF1α1 promoter was cloned and evaluated both in vitro and in vivo. It consistently drives higher levels of exogenous gene expression than CMV in diverse cell lines. Importantly, transgene expression was achieved in various organs of transgenic mice and in muscle tissue following in vivo electroporation. These findings establish the bbEF1α1 promoter as a powerful ubiquitous driver of gene expression, offering high stability with broad applications in gene therapy, biopharmaceutical production, and functional genomics.