Space germs are out there, and the sad truth is that our immune systems aren’t prepared for them.

In these clearly unsettling and upsetting times, the prospect of escaping to another planet may seem like sheer bliss. But wait, not so fast, I have some predictably grim news for you. As it turns out, the bacteria and viruses beyond Earth may be just as deadly as the home-grown kind, if not more so.

Researchers from the universities of Aberdeen and Exeter have revealed that the immune systems of mammals – humans included – may struggle to detect and combat germs from other worlds.

What are space germs?

For as long as alien life has been pondered, scientists have wondered what form such life may take. The most likely would be life in its simplest form: Microorganisms, such as bacteria and viruses.

These space germs may be comprised of different amino acids to their Earth-bound equivalents. Amino acids are the key building blocks that make up all life, and some are more common than others.

Meteorites found on Earth have been known to contain rare amino acids. It is thought that alien microbes may contain some combination of these lesser-seen amino acids. Lead author of the study Dr Katja Schaefer, of the University of Exeter, explained this. “Life on Earth relies on essentially 22 amino acids.”

“We hypothesised that lifeforms that evolved in an environment of different amino acids might contain them in their structure.”

Space germs may contain amino acids similar to the ones found in meteorites. This impact crater site in Arizona is where such a meteorite has been found.
Meteorites, found at impact crater sites like this one in Arizona, have been known to contain rare amino acids.

The experiment

The researchers chemically synthesised peptides (combinations of amino acids) containing the two rare amino acids found in space: isovaline and α-aminoisobutyric acid.

These ‘exo-peptides’ were then inserted into the immune cells of mice, which function in a similar way to a human’s. The reactions of these mice’s T-cells (which are key to immune responses) were then observed.

The immune response was found be “less efficient” when dealing with the ‘exo-peptides’. The activation level of T-cells was found to be 15% and 61%.

When exposed to peptides comprised entirely of common amino acids found on Earth, this level is much higher – at 82% and 91%.

“Our investigation showed that these exo-peptides were still processed, and T cells were still activated, but these responses were less efficient than for ‘ordinary’ Earth peptides,” Dr Schaefer explained.

“We therefore speculate that contact with extra-terrestrial microorganisms might pose an immunological risk for space missions aiming to retrieve organisms from exoplanets and moons.”

What space germs may other planets and moons possess? We have yet to find out.
What space germs may other planets and moons possess? We have yet to find out.

A timely discovery

Given the ongoing global coronavirus pandemic, the apt timing of this research isn’t lost on the team.

Professor Neil Gow, Deputy Vice-Chancellor at the University of Exeter, gave his thoughts. “The world is now only too aware of the immune challenge posed by the emergence of brand new pathogens.”

“Would our immune system be able to detect proteins made from these non-terrestrial building blocks if such organisms were discovered and were brought back to Earth and then accidentally escaped?”

“Our paper addresses this hypothetical event.”

So, might an extraterrestrial microbial threat be seen in our future? It is certainly a possibility. Much like how the ill-fated Martians of The War of the Worlds were defeated by Earth’s simple bacteria, we may one day be challenged by the space germs of another world.

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