Veterinary Science

For decades, scientists have believed that a protein called interferon tau (IFNT) is indispensable for pregnancy in cattle. Produced by the early embryo, it was thought to signal its presence to the mother and prevent the hormonal changes that would otherwise end the pregnancy.

Researchers at LMU have now challenged this established model in a study recently published in the journal Nature Communications. Cattle embryos completely lacking IFNT can establish and maintain pregnancies, even resulting in the birth of healthy calves.

Birth of genetically modified calves without interferon tau

The team, led by Dr. Asghar Ali, postdoctoral researcher at LMU’s Gene Center Munich, and Professor Eckhard Wolf, Chair of Molecular Animal Breeding and Biotechnology and Vice Dean at LMU’s Faculty of Veterinary Medicine, used CRISPR-Cas9 gene editing to eliminate all functional copies of the IFNT genes in bovine cells. Then they generated cloned embryos from these modified cell nuclei and transferred them into recipient animals.

The results surprised the researchers: Despite producing no IFNT, the embryos developed normally during the earliest stages and successfully established pregnancies. On 26 February 2026, two healthy female calves were born, both confirmed to lack functional IFNT genes.

“Our findings challenge a fundamental assumption in reproductive biology. We have demonstrated that cattle embryos can establish pregnancies and develop to term without producing interferon tau, a signal previously considered indispensable,” says Asghar Ali, corresponding author of the study.

More information in LMU press release

Original publication:
Pregnancy establishment in cattle without embryonic interferon tau.
Ali A, Zakhartchenko V, Güngör T, Nüske S, Stöckl JB, Hecken S, Hauser A, Krebs S, Reese S, Suchowski M, Friedl R, Schwanitz S, Scholz AM, Blutke A, Protschka M, Büttner M, Fröhlich T, Reichenbach HD, Wolf E. 
Nat Commun. 2026 Oct 8;17(1):10609. https://doi.org/10.1038/s41467-026-78446-4