2.2 Phylogenetic analysis
The phylogenetic tree of all 164 species and 38 selected species was constructed by MEGA X[15] using the neighbor-joining (NJ) method with 1000 bootstrap replicates. Multiple sequences alignment used for phylogenetic tree construction was generated by the MAFFT software[16] with default parameters. We further searched for conserved domains within human TMPRSS2 protein against the NCBI’s CDD v3.18 – 55570 PSSMs database[17] by setting the expected value threshold of 0.01 and 500 maximum number of hits. We then constructed a phylogenetic tree using protein sequences of domain regions by use of the same NJ method as the whole amino sequences.