Characterisation of the major body fluid proteins from Dioctophyma renale ? the giant kidney worm ? novel protein types and potential diagnostic markers

MALCOLM W. KENNEDY; BETINA CÓRSICO; MARCOS BUTTI; GISELA R. FRANCHINI; A. NAHILI GIORELLO; NILDA E. RADMAN

Cape Cod

Congreso; Molecular Helminthology: An Integrated Approach; 2017

Introduction: Dyoctophyma renale is the largest parasitic nematode of terrestrial vertebrates and is distributed worldwide. It develops in, and completely destroys mammalian kidneys, and is a debilitating and potentially lethal parasite of humans, domestic animals (dogs in particular), and certain endangered wild canids. Unequivocal cases in humans have been documented in several countries. Principal concerns about dioctophymatosis include the lack of sensitive and specific diagnostic techniques to detect cases of nonpatent unisexual infections in the kidneys, ectopically located worms, prepatent asymptomatic infections, or with which to survey the levels of exposure in human populations. We have initiated a detailed molecular, biophysical and immunochemical analysis of proteins from D. renale in order to establish improved diagnostic markers.Methods: We have purified the two major proteins from the pseudocelomic body fluid (PCF) of adult D. renale and have characterised them using biochemical and spectrophotometric techniques. The immunogenicity of PCF proteins was evaluated using immunoblot analysis using sera from infected dogs. Results: PCF of D. renale contains two highly abundant proteins in both males and females, one of 44 kDa (P44) that binds lipids in a fluorescence-based assay using environment-sensitive probes, and another of 17 kDa (P17) that is intensely red, probably haem-containing. Preliminary N-terminal sequencing of these proteins revealed no apparent homologues in available databases. Additionally, we found P44 and other components of PCF to be targets of strong antibody responses in naturally infected dogs.Discussion: D. renale´s P44 appears to be a novel class of hydrophobic ligand binding protein with a highly apolar binding site and may be specific to clade I nematodes. P17 is probably involved in oxygen transport essential for a large parasite living in an oxygen-poor environment. The immunogenicity of these two proteins in natural infections, and their apparent phylogenic restriction, make them good candidates for species-specific diagnostics.