American Society of Hirudotherapy

The hirudin-like factors HLF3 and HLF4-hidden hirudins of European medicinal leeches

Research article published in Parasitology research (2020)

Last Updated: June 18, 2026Reviewed by: ASH Editorial Board
Research article — evidence reviewArticle reference
Evidence: In vitro / laboratoryDrug DevelopmentGenomics & ProteomicsMüller C et al. · Parasitology research, 2020

Abstract

The hirudin-like factors 3 (HLF3) and 4 (HLF4) belong to a new class of leech-derived factors and are present in specimens of the three European medicinal leeches, Hirudo medicinalis, Hirudo verbana, and Hirudo orientalis, respectively. Here we describe the functional analysis of natural and synthetic variants of HLF3 and HLF4. Whereas the natural variants display only very low or no detectable anti-coagulatory activities, modifications within the N-termini in combination with an exchange of the central globular domain have the potency to greatly enhance the inhibitory effects of respective HLF3 and HLF4 variants on blood coagulation. Our results support previous observations on the crucial importance of all parts (both the N- and C-termini as well as the central globular domains) of hirudin and HLF molecules for thrombin inhibition.

Abstract sourced from PubMed (NCBI) for the cited record. See the original publication for the authoritative version.

Publication typeJournal Article
Indexed MeSH termsAmino Acid SequenceAnimalsBlood CoagulationHirudinsHirudo medicinalisLeechesProtein DomainsRecombinant ProteinsStructure-Activity RelationshipThrombin

Summary

The hirudin-like factors 3 (HLF3) and 4 (HLF4) belong to a new class of leech-derived factors and are present in specimens of the three European medicinal leeches, Hirudo medicinalis, Hirudo verbana, and Hirudo orientalis, respectively.

Why This Matters for Hirudotherapy

This study functionally characterized hirudin-like factors 3 and 4 (HLF3, HLF4), a newly described class of leech-derived factors present in three European medicinal leech species (Hirudo medicinalis, H. verbana, and H. orientalis), finding that natural variants showed minimal or undetectable anticoagulant activity while engineered modifications to the N-termini combined with exchange of the central globular domain substantially enhanced thrombin inhibition. This work directly advances understanding of the leech salivary secretome by expanding the known repertoire of thrombin-targeting molecules beyond classic hirudin and clarifying how each structural region—N-terminus, C-terminus, and central globular domain—contributes to inhibitory potency. The clinical relevance to hirudotherapy remains indirect, as the enhanced anticoagulant effects resulted from engineered molecular modifications rather than natural leech secretions, and the abstract provides no in vivo or therapeutic outcome data.

Citation

The hirudin-like factors HLF3 and HLF4-hidden hirudins of European medicinal leeches.

Müller C et al. · Parasitology research, 2020

DOI

Added to ASH library: March 18, 2026 · Site last updated: June 18, 2026

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