Why is Delta so infectious? New lab tool spotlights little noticed mutation

New lab tool spotlights mutation that speeds spread of Delta variant

As the world has learned to its cost, the Delta variant of the pandemic coronavirus is more than twice as infectious as previous strains. Just what drives Delta’s ability to spread so rapidly hasn’t been clear, however. Now, a new lab strategy that makes it possible to quickly and safely study the effects of mutations in SARS-CoV-2 variants has delivered one answer: a little-noticed mutation in Delta that allows the virus to stuff more of its genetic code into host cells, thus boosting the chances that each infected cell will spread the virus to another cell.

That discovery, published today in Science, is “a big deal,” says Michael Summers, a structural biologist at the University of Maryland, Baltimore County—not just because it helps explain Delta’s ravages. The new system, developed by Nobel Prize winner Jennifer Doudna of the University of California (UC), Berkeley, and her colleagues, is a powerful tool for understanding current SARS-CoV-2 variants and exploring how future variants might affect the pandemic, he says. “The system she has developed allows you to look at any mutation and its influence on key parts of viral replication. … That can now be studied in a much easier way by a lot more scientists.” ...