American Society of Hirudotherapy

Genomics & Proteomics

Modern molecular approaches to medicinal leech biology

Last Updated: May 27, 2026Reviewed by: Andrei Dokukin, MD
Omics & molecular biologyDiscovery science

Last updated: November 1, 2026

Classical biochemistry isolated and characterized individual bioactive components of medicinal leech salivary gland secretion over several decades of painstaking protein purification. Modern “omics” technologies have changed this picture: genome sequencing, transcriptomics and mass spectrometry proteomics have identified 189 proteins in the salivary secretion of H. medicinalis and 344 in H. verbana (Babenko et al. 2020), revealing an unexpectedly complex pharmacological arsenal and opening new avenues for drug discovery.

Genome Assemblies

Kvist et al. (2020)

A draft Hirudo medicinalis genome assembly. Kvist et al. (2020) found 15 known anticoagulation factors and 17 other antihemostasis-linked proteins by BLAST and phylogenetic analysis. Eglin C and destabilase had the highest copy numbers (seven each), whereas hirudin occurred as a single copy.

Genome Features

  • A draft genome assembly (proteome work: Babenko et al. 2020)
  • a draft genome assembly (Babenko et al. 2020)
  • 15 anticoagulation gene families identified
  • 17 antihemostatic gene families identified
  • Gene duplication in hirudin/eglin families
  • Repeat content: characteristic of lophotrochozoan genomes

Transcriptomics — Salivary Cell Gene Expression

Babenko et al. (2020)

RNA-seq analysis of salivary cells from three Hirudo species (H. medicinalis, H. orientalis, H. verbana). Co-authored by I.P. Baskova, linking classical biochemistry with modern genomics. Differential expression analysis identified 102, 174 and 72 salivary-cell transcripts in H. medicinalis, H. orientalis and H. verbana respectively; the authors report that the secretions of the three species have a similar composition.

Guan et al. (2024)

Investigated starvation-induced changes in the salivary proteome and transcriptome. Leeches upregulate specific anticoagulant and tissue-penetration genes during prolonged fasting, optimizing SGS composition for the next feeding event. This finding explains the traditional practice of using “hungy” leeches in clinical application — they produce a more potent and complex secretion.

Proteomics — Mass Spectrometry Era

Liu et al. (2019)

Comprehensive proteomic analysis using LC-MS/MS deduced 434 full-length protein sequences from combined leech salivary-gland proteome and transcriptome data and, after integrating both datasets, found 44 proteins and 221 transcripts of bioactive molecules involved in leech sucking pathways (Liu et al. 2019, PMID 30880165).

Novel ClassFunctionDrug Discovery Potential
M12/M13 ProteasesMetalloprotease tissue remodelingWound healing, anti-fibrotic
CRISP ProteinsCysteine-rich secretory proteins; immune modulationAnti-inflammatory leads
ApyraseADP hydrolysis; antiplateletAntiplatelet drug leads
Adenosine DeaminaseAdenosine metabolism; vasodilationCardiovascular modulation
CystatinsCysteine protease inhibitionAnti-inflammatory, antiparasitic
FicolinsLectin complement pathway activationInnate immunity modulation

Structural Biology Breakthroughs

Tandem-Hirudin (Lukas et al., 2022)

Discovery of the first oligomeric hirudin — a hirudin variant that forms tandem multimers. Unlike classical hirudin, tandem-hirudin shows no direct thrombin inhibitory activity, suggesting a novel, as-yet-uncharacterized biological function. This finding challenges the assumption that all hirudin family members are anticoagulants.

Destabilase Crystal Structure (Marin et al., 2023)

Crystal structure of destabilase resolved at 1.1 Angstrom resolution — the first high-resolution structure of this enzyme (a second structure was solved at 1.4 Angstrom). The structures show a sodium ion bound between Glu34 and Asp46, which may explain inhibition of the muramidase activity, and, together with a 1 microsecond molecular-dynamics simulation, led the authors to revise the earlier Ser49/Lys58 hypothesis for the isopeptidase (fibrin-dissolving) activity, proposing His112 rather than Lys58 as the general base.

From single compounds to proteome-scale studies

Paradigm Shift

Classical biochemistry (1950s–2000s) identified approximately 30–40 bioactive components through painstaking individual protein purification. Modern omics approaches have expanded this to over 200 identified proteins. The majority remain functionally uncharacterized — each representing a potential drug lead or biological insight into the most pharmacologically complex animal secretion known.

How many salivary proteins does the medicinal leech have?

Mass spectrometry identified 189 proteins in the salivary cell secretion of Hirudo medicinalis, 344 in H. verbana and 86 in H. orientalis (Babenko et al. 2020). Liu et al. (2019) deduced 434 full-length salivary protein sequences in leeches whose species the abstract does not name. No published source gives a combined “440+” total. Liu et al. 2019 summary.

Future Directions

Single-Cell Transcriptomics

scRNA-seq of individual salivary gland cells will reveal which cell types produce which SGS components, enabling targeted manipulation of specific bioactive pathways.

CRISPR Functional Studies

Gene knockout/knockdown in leech salivary gland cells will establish definitive gene–function relationships for the hundreds of uncharacterized salivary proteins identified by proteomics.

Synthetic Biology

Recombinant production of individual SGS components or designed multi-component cocktails could enable standardized, leech-free delivery of specific therapeutic combinations.

Studies in the ASH clinical-study library

Entries from our clinical-study library filed under this topic. Each entry states its own study design and GRADE rating.

All studies in the library

Related Resources

SGS Composition

Classical biochemistry of salivary components.

Compound Reference

Complete bioactive component database.

Drug Pipeline

Pharmaceutical development from leech biology.

This website provides educational information and does not constitute medical advice, diagnosis, or treatment recommendations. Medicinal leech therapy carries clinically meaningful risks and should be performed only by qualified clinicians under institutionally approved protocols. FDA 510(k) clearance for medicinal leeches is limited to specific indications; investigational and off-label discussions are labeled accordingly. For patient-specific guidance, consult a qualified healthcare provider.