In Delaware, Dr. Perilla and Dr. Hadden-Perilla are studying a moment even earlier in the process, when the coronavirus enters a human cell and unravels its genome. This transforms the virus from a hardy infectious particle, which must move through the air and evade immune cells, into a naked and vulnerable template, unspooling itself for evaluation. The coronavirus “is a shape-shifter,” Dr. Hadden-Perilla said. But scientists don’t fully understand how the virus can tell when it’s time to disrobe.

Dr. Perilla said he suspected that some sort of signal inside human cells might trigger the virus’s shell to pop open and release its RNA. That’s the case for the Ebola virus, he said: “It wants to open.” Stopping that process could be vital to halting an infection before it spirals out of control.