Virus hunter Ian Lipkin from Columbia University says. "“When people analyze samples from people who are ill, they have some idea in mind. This is probably an enterovirus, or maybe it's a herpesvirus. They then do a specific assay for that particular agent. They don't usually have the capacity to look broadly.”
"In the 120 or so years since viruses were first discovered, our ability to identify them, and diagnose the diseases they cause, has improved enormously. But even the most cutting-edge of techniques have limitations. Sequencing technologies allow scientists to unambiguously decipher the genetic material of viruses in a sample, but they suffer from poor sensitivity—that is, they sometimes miss what they're trying to find. That's because viral genes are often swamped by those of their hosts, so sequencing them is like trying to find a needle in a haystack.
PCR, a method for amplifying DNA, solves that problem by making lots and lots of copies of the needle beforehand. It is exquisitely sensitive but it's also hard to do in bulk, and you need to have some idea of what you're looking for in the first place."
A new technique, "VirCapSeq-VERT, combines the best features of these techniques, and throws in a few more for good measure. Think of it as a massive exercise in fishing for viruses. To make the hooks, the team identified and synthesized distinctive stretches of DNA from the genomes of every known group of virus that affects humans and other vertebrates. They ended up with two million of these hooks, each of which was baited to snag a different virus. If you dangle them in a blood sample, yank them out, and then sequence everything that's attached to them, you end up with the full genome of every virus present."
Full article from The Atlantic, Science section: