Fasciola hepatica Cathepsin L Zymogens: Immuno-Proteomic Evidence for Highly Immunogenic Zymogen-Specific Conformational Epitopes to Support Diagnostics Development

• Published in: Journal of proteome research Vol. 21; no. 8; pp. 1997 - 2010
• Main Authors: Collett, Clare F., Phillips, Helen C., Fisher, Maggie, Smith, Sian, Fenn, Caroline, Goodwin, Phil, Morphew, Russell M., Brophy, Peter M.
• Format: Journal Article
• Language: English
• Published: American Chemical Society 05.08.2022
• Subjects: recombinant; diagnostics; triclabendazole; fasciolosis; cathepsin
• ISSN: 1535-3893; 1535-3907
• DOI: 10.1021/acs.jproteome.2c00299

Fasciola hepatica, the common liver fluke and causative agent of zoonotic fasciolosis, impacts on food security with global economic losses of over $3.2 BN per annum through deterioration of animal health, productivity losses, and livestock death and is also re-emerging as a foodborne human disease. Cathepsin proteases present a major vaccine and diagnostic target of the F. hepatica excretory/secretory (ES) proteome, but utilization in diagnostics of the highly antigenic zymogen stage of these proteins is surprisingly yet to be fully exploited. Following an immuno-proteomic investigation of recombinant and native procathepsins ((r)­FhpCL1), including mass spectrometric analyses (DOI: 10.6019/PXD030293), and using counterpart polyclonal antibodies to a recombinant mutant procathepsin L (anti-rFhΔpCL1), we have confirmed recombinant and native cathepsin L zymogens contain conserved, highly antigenic epitopes that are conformationally dependent. Furthermore, using diagnostic platforms, including pilot serum and fecal antigen capture enzyme-linked immunosorbent assay (ELISA) tests, the diagnostic capacities of cathepsin L zymogens were assessed and validated, offering promising efficacy as markers of infection and for monitoring treatment efficacy.