Natural and induced antibodies contribute to differential susceptibility to secondary cystic echinococcosis of Balb/c and C57Bl/6 mice

MOURGLIA ETTLIN G; CUCHER M; ARBILDI P; ROSENZVIT M; DEMATTEIS S

IMMUNOBIOLOGY.

ELSEVIER GMBH

Año: 2016 vol. 221 p. 103 - 115

0171-2985

tAntibodies are key immune players in several helminth infections and animal models have been centralfor the identification of their mechanisms of protection. Murine secondary cystic echinococcosis is auseful model for studying Echinococcus granulosus immunobiology, being the immune profile mountedby the experimental host a determinant of parasite success or failure in infection establishment. In thepresent study, we analyzed infection outcome using Balb/c and C57Bl/6 mice strains, and compared theirantibody responses in terms of quality and intensity. Our results showed that Balb/c is a highly susceptiblestrain to secondary cystic echinococcosis, while C57Bl/6 mice are quite resistant. Moreover, significantdifferences between strains were observed in natural and induced antibodies recognizing E. granulosusantigens, both at the systemic and peritoneal levels. Natural cross-reacting IgM, IgG2b and IgG3 antibodieswere detected in sera from both strains but with different intensities, and ? remarkably ? natural IgG2bshowed to be an intrinsic correlate of protection in both mice strains. Interestingly, naïve C57Bl/6 serumdisplayed a higher protoscolicidal activity, and heterologous ? but not homologous ? transference ofC57Bl/6 naïve serum into Balb/c mice, significantly reduced their infection susceptibility. In the peritonealcavity, different levels of natural cross-reacting IgM and IgG3 antibodies were detected in both micestrains, while cross-reacting IgG2b was detected only in C57Bl/6 mice. On the other hand, infected micefrom both strains developed isotype-mixed antibody responses, with Balb/c mice biasing their responsetowards high avidity IgG1 and C57Bl/6 mice showing a predominance of mixed IgM/IgG2c/IgG2b/IgG3.In this regard, IgG1 levels showed to be a correlate of susceptibility in both mice strains. In conclusion,our results suggest that antibodies ? either natural or induced ? play a role in the susceptibility degreeto murine secondary cystic echinococcosis.