Covid-19 coronavirus binding to human cell, conceptual computer illustration. SARS-CoV-2 coronavirus (previously 2019-nCoV) binding to an ACE2 receptor on a human cell (not to scale). SARS-CoV-2 causes the respiratory infection Covid-19, which can lead to fatal pneumonia. ACE2 (angiotensin-converting enzyme 2) is a membrane-bound aminopeptidase, the key host receptor for the spike glycoprotein of SARS-CoV-2 which serves as initial step in the development of coronavirus infection on a cellular level and a potential target for treatment strategy.