Endogenous retroviruses (ERVs) are involved in cellular proliferation, pluripotency, tissue‐specific remodelling and regulation of developmental processes. These elements are transcriptionally active in mouse and human pre‐implantation embryos. Empirical evidence indicates that regulatory networks involved with ERV transcripts are responsible for pluripotency and totipotency at certain stages of mouse and human pre‐implantation development. Yet, the expression in pre‐implantation bovine embryo remains unidentified. To determine whether two members of bovine endogenous retroviruses, BERV‐K1 and BERV‐K2, are expressed in the pre‐implantation bovine embryo, each embryonic stage developed in vitro and was subjected to RNA release, reverse transcription and quantitative PCR. We found that BERV‐K1 and BERV‐K2 are expressed throughout different stages of pre‐implantation development. The higher level of expression was detected in embryonic blastomeres with totipotent/pluripotent status (two‐cell to 16‐cell stages), while the more differentiated blastocyst stage showed significantly lower levels of ERVs expression. These findings suggest a possible role for endogenous retroviruses in the establishment of totipotent and pluripotent states in pre‐implantation bovine embryo, similar to functions which have been suggested for these elements in human and mouse embryos.

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