Fig. 4. Model illustrating the contributions of archaea to the origins of eukaryotic defense mechanisms.

Based on our reconstructions of structures and phylogeny in the study, we propose that early forms of both the viperin and argonautes defense systems were inherited from Asgardarchaeota via the LECA (last eukaryotic common ancestor) into modern eukaryotes. However, other systems present in Asgard-like Mokosh appear to have originated from bacteria, highlighting that both prokaryotes have an important role on the origin of defense mechanisms in Eukaryotes. The known mechanisms of mokosh, argonaute, and viperin defense systems are illustrated at the bottom. Created using BioRender.com, released under a Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International license.