KRT18 and infection: Further, hACE2 expression after AAV-hACE2 intranasal inoculation is restricted to the respiratory system whereas transgene expression may be widespread [26,50,51] and result in infection in organs that are not usually associated with SARS-CoV-2 infection such as direct infection in brains of K18 hACE2 transgenic mice, which is a major factor contributing to the fatal outcome.