“Virologists have infected millions of miniature organs with SARS-CoV-2, to learn how the virus wreaks havoc and how to stop it,” writes Smriti Mallapaty in the latest issue of Nature. In one study, published in Science Immunology in 2020, researchers used CRISPR in gut organoids to identify two proteins (TMPRSS2 and TMPRSS4) that facilitate the virus entry into human cells, together with the ACE2 receptor. “Other labs are knocking out ACE2 entirely, to see whether the virus can still get in”. Here the full text of the news feature.