Scientists Find Microscopic Viruses 'Biting' Onto Each Other

Do vampires really exist? People been trying to put the debate to rest for centuries, but a recent discovery about the behavior of certain viruses might have answers for us after all. Well, sort of...

Most people known that viruses rely on the cellular functions of other organisms to survive. But a team of researchers at the University of Maryland Baltimore County (UMBC) have found a little twist in this theory - there's one type of virus that actually feed on other viruses. In a recent study, led by biologist Tagide deCarvalho, the researchers found mobile genetic elements (MGEs) "piggyback" on other viruses, which are known as "helper" viruses. "When I saw it, I was like, 'I can't believe this.' No one has ever seen a bacteriophage – or any other virus – attach to another virus." There's a particular type called satellite nucleic acid, which relies on other viruses to build its machinery. One example is the Enterobacteria phage P4, which hangs out inside an Escherichia coli bacterium. But when it pairs up with Enterobacteria phage P2, the latter creates protein overcoats for P4, covering the nucleic acid fragments until the cell bursts.

After studying these organisms more closely, the UMBC researchers stumbled upon a whole new level of weird: they found satellite phages attacking Streptomyces bacteria. Unlike the P4s, these phages can make their own coat but but lack the tail-like structure that helps them poke through a host's defenses. And that's where the helper viruses comes to their rescue, using their tails to grab onto the larger virus. In the researchers' words, it's like they were "biting" onto their helpers like microscopic vampires.

The team observed 40 out of 50 helper phages having a satellite attached, while the 10 satellite-free ones appeared to have fibers around their throats, like "bite marks." According to senior author of the study Ivan Erill, this attachment makes sense - it ensures the MGE enters the cell at the right time. But according to the scientists, there's definitely more of these viral tag-alongs out there, waiting to be discovered. Stay tuned...