Dödligt virus från Kina orsakar panik (SARS-CoV-2, COVID-19)

/.../But SARS-CoV-2 doesn’t appear to be a savage destroyer of cells. Although it’s too early to know for sure, the virus’s fatality rate seems to be roughly 10 times that of the flu. “You would think that’s because it’s just a killing machine,” says Max Krummel, PhD, UCSF’s Smith Professor of Experimental Pathology and chair of the Bakar ImmunoX initiative. So far, however, the science suggests otherwise.

“One of the weirder things about this new coronavirus is it doesn’t seem to be incredibly cytopathic, by which we mean cell-killing,” Krummel says. “Flu is really cytopathic; if you add it to human cells in a petri dish, the cells burst within 18 hours.” But when UCSF researchers subjected human cells to SARS-CoV-2, many of the infected cells never perished. “It’s pretty compelling data that maybe we’re not dealing with a hugely aggressive virus,” Krummel says.

The bigger provocation, he suspects, may be your own immune system. Like any pathogen, SARS-CoV-2 will trigger an immune attack within minutes of entering your body. This counterstrike is extraordinarily complex, involving many tactics, cells, and molecules. In a UCSF study called COMET (COVID-19 Multi-Phenotyping for Effective Therapies), Krummel and other scientists have been observing this immune warfare in more than 30 people admitted to UCSF hospitals with COVID-19 and other respiratory infections. “What we’re doing is looking at patients’ blood, their genes, and the secretions from their noses and lungs, and we’re asking, ‘What’s your army? What’s your response strategy?’”

An early analysis of COMET data, Krummel says, suggests that the immune systems of many hospitalized patients mobilize differently – and more aggressively – against SARS-CoV-2 than against influenza viruses, which cause the flu. Their lungs are ravaged, these data suggest, not by the virus alone but by the detritus of an immunological battle gone awry. This rogue immune response could explain why, around day 11 of a COVID-19 infection, patients often develop a severe pneumonia known as acute respiratory distress syndrome, or ARDS.