Comprehensive developmental somatic proteome atlas of Haemonchus contortus underpinned by a chromosome-scale genome and deep tandem mass spectrometry

Haemonchus contortus is a highly pathogenic, blood-feeding nematode that causes widespread disease and significant economic loss in livestock worldwide. Previous proteomic studies were constrained by incomplete genomic resources and limited analytical sensitivity, impeding comprehensive profiling across life stages. In this study, we integrated advanced tandem mass spectrometry with a chromosome-scale genome assembly of the Haecon-5 strain to construct the most detailed somatic proteome of H. contortus to date. We identified and quantified 7,002 proteins across five key developmental stages and sexes (i.e. egg, L3, L4, adult female and adult male), tripling the number identified in previous studies. Comparative analyses revealed pronounced stage-specific expression and functional specialisation, with parasitic stages enriched in proteins linked to metabolism, cellular function and environmental sensing. Fifteen proteins associated with the hypoxia-inducible factor 1 (HIF-1) signalling pathway were upregulated in parasitic stages, suggesting a role in adaptation to hypoxia. Additionally, 150 proteases implicated in haemoglobin degradation were characterised, and functional assays confirmed markedly elevated haemoglobinolytic activity in blood-feeding stages. These findings offer key insights into H. contortus development and parasitism, and establish a high-resolution proteomic framework to underpin fundamental biological studies and enable the discovery of molecular targets for novel interventions against this and related nematodes.