DPP4 and coinfection: Furthermore, host receptors utilized by other coronaviruses (e.g., ANPEP and DPP4) are co-expressed with the SARS-CoV-2 receptor (ACE2) at the single-cell level in respiratory and/or gastrointestinal epithelial cells (Tables S9 and S10) [33], which could facilitate co-infection at the cellular level (a prerequisite for genomic recombination).