2.1 Samples and data
164 complete TMPRSS2 protein sequences of 164 animal species (one protein sequence for each species) were collected from NCBI, including 80 Mammalia, 34 Aves, 13 Reptilia, 3 Amphibia, and 34 fish. Pig, horse, cattle, duck, goose, chicken, dog, cat, and hamster that have potentially direct contacts with humans.. The accession number of each sequence is listed in Table S1.