ACE2 receptor and TMPRSS2 are highly expressed in GI cells, particularly enterochromaffin cells that also express NRP1, suggesting that enteric glial cells and neurons infected with SARS-CoV-2 work as an axonal retrograde transport route to the CNS via the vagus nerve transmitting the infection to the brainstem vagal centers (nucleus tractus solitaries) (Figure 1) [46]. The gene discussed is TMPRSS2; the disease is infection.