claim: the sars-cov-2 and other human coronavirus spike proteins are fine-tuned towards temperature and proteases of the human cell
evidence_1: we here reveal features of the coronavirus spike (s) protein, which optimize the virus towards different parts of the respiratory tract.", "coronavirus spikes exhibit distinct temperature preference to precisely match the upper (~33°c) or lower (37°c) airways.", "significance statement the rapid spread of sars-cov-2, the cause of covid-19, is related to abundant replication in the upper airways, which is not observed for other highly pathogenic human coronaviruses.", "collectively, our findings indicate how the coronavirus spike protein is fine- tuned towards the temperature and protease conditions of the airways, to enhance virus transmission and pathology.", 
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  "even stronger preference for the upper airway temperature of 33°c was evident for the s protein of hcov-229e, a common cold coronavirus.")