Glycan moieties in Entamoeba histolytica ubiquitin are immunodominant

Abstract

The ubiquitin-proteasome system plays a central role performing several functions to maintain parasite homeostasis. We have reported the partial characterization of N-linked glycosylation profile in E. histolytica ubiquitin (EhUb). Here we examined the immunogenicity and antigenicity of carbohydrates in EhUbiquitin. Rabbits were immunized with purified EhUbiquitin or purified recombinant rUb expressed by E. coli. Using Western Blot, we explored the immunogenicity and antigenicity of protein portion and carbohydrates moiety. Interestingly, immunized rabbits produced antibodies to both Ub glycoprotein and rUb; but antibodies against carbohydrates were immunodominant, rather than antibodies to the protein moiety of EhUbiquitin. In addition, we observed that antibodies to protein moiety are not conserved in serum unless antigen is continually administrated. Conversely, anti-Ub glycoprotein antibodies are well maintained in circulation. In humans, infection with Entamoeba histolytica induces strong IgG anti-Ub response. The human antibodies recognize both, the protein moieties and the glycosylated structure. Entamoeba histolytica ubiquitin is immunogenic and antigenic. The glycan moieties are immunodominant and induces IgG. These data open the door to use carbohydrates as potential targets for diagnose tests, drugs and vaccine to prevent this parasitic disease.

Keywords: Entamoeba histolytica; EhUbiquitin; antigen; glycans; immunogen; polysaccharides; ubiquitin.