Scientists discover weird virus-like 'obelisks' in the human gut and mouth

We don’t know what they do, but they like to hang out inside bacteria.

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We may have an adequate understanding of the human body in that, well, we invented aspirin and sequenced the genome, but researchers still find out new things about the humble homo sapien all of the time. Case in point? Scientists just discovered a previously unknown entity hanging out in the human gut and mouth. The researchers are calling these virus-like structures “obelisks”, due to their presumed microscopic shape.

These entities replicate like viruses, but are much smaller and simpler. Due to the minuscule size, they fall into the “viroid” class, which are typically single-stranded RNAs without a protein shell. However, most viroids are infectious agents that cause disease and it doesn’t look like that’s the case with these lil obelisks, as reported by Live Science.

So why are they inside of us and what do they do? That’s the big question. The discoverers at Stanford University, the University of Toronto and the Technical University of Valencia have some theories. They may influence gene activity within the human microbiome, though they also hang out in the mouth. To that end, they have been found using the common mouth-based bacterium Streptococcus sanguinis as a host. It’s been suggested that these viroids infect various bacteria in both the mouth and gut, though we don’t know why.

Some of the obelisks seem to contain instructions for enzymes required for replication, so they look to be more complex than your average viroid, as indicated by Science. In any event, there has been a “chicken and the egg” debate raging for years over whether viruses evolved from viroids or if viroids actually evolved from viruses, so further study could finally end that argument.

While we don’t exactly know what these obelisk sequences do, scientists have discovered just how prevalent they are in our bodies. These sequences are found in roughly seven percent of human gut bacteria and a whopping 50 percent of mouth bacteria. The gut-based structures also feature a distinctive RNA sequence when compared to the mouth-based obelisks. This diversity has led researchers to proclaim that they “comprise a class of diverse RNAs that have colonized, and gone unnoticed in, human, and global microbiomes.”

“I think this is one more clear indication that we are still exploring the frontiers of this viral universe,” computational biologist Simon Roux of the DOE Joint Genome Institute at Lawrence Berkeley National Laboratory told Science.

“It’s insane,” added Mark Peifer, a cell and developmental biologist at the University of North Carolina at Chapel Hill. “The more we look, the more crazy things we see.”

Speaking of frontier medicine, scientists also recently created custom bacteria to detect cancer cells and biometric implants that detect organ rejection after replacement surgery. The human body may be just about as vast and mysterious as the ocean, or even space, but we’re slowly (ever so slowly) unraveling its puzzles.