Comparative Study of Lefaxin Family in Two Asian Leeches: and .

Thrombotic diseases represent a significant global health burden, particularly for middle-aged and elderly populations. Medicinal leeches, such as and , have been traditionally used for their anticoagulant properties. The genomes of these leeches each harbor three lefaxin genes, which are designated and , respectively. We conducted genomic and transcriptomic sequencing on wild populations of both species. Bioinformatics tools were employed to analyze intraspecific variation, molecular evolution, and protein structures. We expressed recombinant lefaxin proteins in and assessed their anticoagulant activities using in vitro coagulation assays. exhibited greater genetic diversity and stability, whereas showed higher expression levels and hydrophilicity. Both species exhibited purifying selection, indicating conserved function, and their lefaxin structures are similar to the archetypal lefaxin (UniProt No. P86681.1). lefaxins bound Factor Xa more effectively. lefaxins exhibited more robust anticoagulant activity in vitro compared to those from . , a non-hematophagous leech, shows potent anticoagulant activity through lefaxins, challenging traditional views on leech efficacy. This study underscores the potential of lefaxins as therapeutic targets for thrombotic diseases and highlights the need to reconsider the use of various leech species in medicine.