Evaluation of the immunodiagnostic potential of a recombinant surface protein domain fromAcanthamoeba castellanii

Abstract

SUMMARYAcanthamoebaspp. are free-living protists widely distributed in environment, able to cause keratitis, encephalitis and skin lesions in humans and animals.Acanthamoebaspp. exist in two forms: an infective trophozoite and a dormant cyst. Several factors contribute to the pathogenesis ofAcanthamoebaspp. The parasite adhesion to the host cell is the primary step for infection and is mediated by a mannose binding-protein, expressed in the surface and considered the main pathogenicity factor inAcanthamoebaspp. So far, there was no evidence of another surface protein ofAcanthamoebaspp. relevant for host invasion or infection by these organisms. The aims of this study were to identify and characterize anAcanthamoeba castellaniisurface protein and to evaluate its diagnostic potential.In silicopredictions of surface proteins allowed to identify theA. castellaniicalreticulin as a possible surface antigen. The coding sequence of a predicted extracellular domain ofA. castellaniicalreticulin was cloned byin vivohomologous recombination and the recombinant polypeptide (AcCRT29–130) was produced. Its immunodiagnostic potential was assessed in a recombinant antigen-based ELISA with sera from experimentally infected rats that developed keratitis and encephalitis, and sera from patients with encephalitis. The AcCRT29–130was significantly more recognized by sera from encephalitis infected rats in comparison with the non-infected controls. Human sera from encephalitis patients, however presented no significant response. These results showed the AcCRT29–130potential forA. castellaniiinfection immunodiagnosis in animals, with further studies being required for assessment of its use for human infections.