"How the coronavirus infects cells — and why Delta is so dangerous" https://www.nature.com/articles/d41586-021-02039-y https://www.nature.com/articles/d41586-0

"How the coronavirus infects cells — and why Delta is so dangerous" https://www.nature.com/articles/d41586-021-02039-y https://www.nature.com/articles/d41586-021-02039-y "The virus then ejects its genome directly into the cell. By invading in this spring-loaded manner, SARS-CoV-2 infects faster than SARS-CoV and avoids being trapped in endosomes, according to work published in April by Barclay and her colleagues at Imperial College London9. The virus’s speedy entry using TMPRSS2 explains why the malaria drug chloroquine didn’t work in clinical trials as a COVID-19 treatment, despite early promising studies in the lab10. Those turned out to have used cells that rely exclusively on cathepsins for endosomal entry. “When the virus transmits and replicates in the human airway, it doesn’t use endosomes, so chloroquine, which is an endosomal disrupting drug, is not effective in real life,” says Barclay."