ACE and COVID-19: It is also possible that viral particles in CSF are in undetectable trace amounts (19, 20) and may require a highly sensitive method to test in the future (21); (2) Interaction with angiotensin-converting-enzyme (ACE) receptors: Glial cells and neurons in the CNS have been reported to express ACE2 receptors, making them a potential target of COVID-19 and contributing toward morbidity and mortality.