When experts warn that aliens pose a threat to life on Earth, we think of an advanced species that destroys our planet using futuristic weaponry. However, a new study has revealed that deep space microorganisms could pose the greatest threat. The coronavirus pandemic has shown that the disease can stop life on Earth, and if an unknown disease were to travel to our planet via meteorites, the results could be devastating.
Life forms on Earth are based on amino acids, but these amino acids may be slightly different than those potentially found in space.
Researchers from the universities of Aberdeen and Exeter tested how mammalian immune cells responded to peptides (combinations of amino acids) that contain two amino acids that are rare on Earth but commonly found in meteorites.
The study in mice, which have a similar immune response to humans, showed that mammals have a “less efficient” response to peptides commonly found in meteorites.
The researchers examined the reaction of T cells, which are key to immune responses, to the amino acids isovaline and α-aminoisobutyric acid.
The response was weak, with T-cell activation levels of 15 percent and 61 percent, compared to 82 percent and 91 percent when exposed to peptides made entirely of amino acids that are common on Earth.
Professor Neil Gow, deputy vice chancellor (Research and Impact) at the University of Exeter, said: “The world is now too aware of the immune challenge posed by the emergence of new pathogens.
“As a thought experiment, we wonder what would happen if we were exposed to a microorganism that had been recovered from another planet or moon where life had evolved.
“There are some very unusual organic building blocks outside of planet Earth, and these could be used to form the cells of such alien microbes.
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“We chemically synthesize ‘exopeptides’ that contain amino acids that are rare on Earth, and we tested whether a mammalian immune system could detect them.
“Our research showed that these exopeptides were still being processed and T cells were still activated, but these responses were less efficient than those of ‘ordinary’ Earth peptides.
“Therefore, we speculate that contact with extraterrestrial microorganisms could present an immunological risk for space missions aimed at recovering organisms from exoplanets and moons.”
