Phylogenetic tree of aspartic proteases, including Ov-APR-1 from Opisthorchis viverrini (GenBank protein accession no. AAZ39883); protozoa, Plasmodium falciparum (plasmepsin1, P39898): fungi, Laccaria bicolor (XP_001877133), Aspergillus niger (XP_001399855); flatworm, Clonorchis sinensis (AAL14708) Fasciola hepatica (ABJ97285), Schistosoma japonicum (AAC37302), Schistosoma mansoni (AAB63442); arthropod, Aedes aegypti (XP_001657556), Drosophila melanogaster (NP_652013); roundworm, Ancylostoma ceylanicum (AAO22152), Meloidogyne incognita (ABC88426); vertebrates, Homo sapiens (NP_001900), Canis familiaris (NP_001020792), Mus musculus (NP_034113), Bos taurus (BAB21620). The number on each branch represents the bootstrap value from 1000 replicates.