2134/12671672.v1 Katja Schaefer Katja Schaefer Ivy M Dambuza Ivy M Dambuza Sergio Dall’Angelo Sergio Dall’Angelo Raif Yuecel Raif Yuecel Marcel Jaspars Marcel Jaspars Laurent Trembleau Laurent Trembleau Matteo Zanda Matteo Zanda Gordon D Brown Gordon D Brown Mihai G Netea Mihai G Netea Neil AR Gow Neil AR Gow A weakened immune response to synthetic Exo-Peptides predicts a potential biosecurity risk in the retrieval of Exo-Microorganisms Loughborough University 2020 immune response space travel planetary protection infection risk exobiology unusual amino acids 2020-07-23 10:51:30 Journal contribution https://repository.lboro.ac.uk/articles/journal_contribution/A_weakened_immune_response_to_synthetic_Exo-Peptides_predicts_a_potential_biosecurity_risk_in_the_retrieval_of_Exo-Microorganisms/12671672 The discovery of liquid water at several locations in the solar system raises the possibility that microbial life may have evolved outside Earth and as such could be accidently introduced into the Earth’s ecosystem. Unusual sugars or amino acids, like non-proteinogenic isovaline and α-aminoisobutyric acid that are vanishingly rare or absent from life forms on Earth, have been found in high abundance on non-terrestrial carbonaceous meteorites. It is therefore conceivable that exo-microorganisms might contain proteins that include these rare amino acids. We therefore asked whether the mammalian immune system would be able to recognize and induce appropriate immune responses to putative proteinaceous antigens that include these rare amino acids. To address this, we synthesised peptide antigens based on a backbone of ovalbumin and introduced isovaline and α-aminoisobutyric acid residues and demonstrated that these peptides can promote naïve OT-I cell activation and proliferation, but did so less efficiently than the canonical peptides. This is relevant to the biosecurity of missions that may retrieve samples from exoplanets and moons that have conditions that may be permissive for life, suggesting that accidental contamination and exposure to exo-microorganisms with such distinct proteomes might pose an immunological challenge.