CONICET | Buscador de Institutos y Recursos Humanos

We have designed and characterized with very goodresults a novel pertussis vaccine candidate based on outer membrane vesicles(OMVs). OMVs are nanosized lipid vesicles that contain proteins, lipids,peptidoglycan and toxins. We detected that OMVs from B. pertussis are highlyimmunogenic, inexpensive to produce and very stable. Here, we analyze the contribution of the integrity ofOMVs on their immunogenic and protective capacity against pertussis. The ruptureof the OMVs was carried out mechanically using a Ribolyser Sample Homogenizer.The loss of the OMVs integrity was confirmed by transmission electron microscopyand dynamic light scattering technique. By SDS-PAGE we detected that theelectrophoretic protein and LPS profiles of ribolyser-treated OMVs were similarto those observed for non-treated OMVs. By performing a comparative study with non-treatedOMVs, we demonstrated in mice that ribolyser-treated OMVs exhibited lower protectedcapacity against sublethal B. pertussis infections. Indeed, the B. pertussisloads were significantly increased in the lungs of ribolyser-treated OMVs-vaccinatedanimals, with the CFUs recovered being increased by 2 log units above thosedetected in the non-treated OMVs immunized animals, (p<0.001). We also detectedthat ribolyser-treated OMVs induced lower levels IgG antibodies against B. pertussiswhole-cell lysates. Of interest was that the ribolyser-treated OMVs -generatedsera with lower bactericidal capabilities than that detected with the non-treatedOMVs-induced sera, suggesting that those activities were involved in theclearance of B. pertussis. Finally, by performing experiments combining OMVswith unrelated antigen, we demonstrated that ribolyser-treated OMVs has a reducedadjuvant capacity in comparison with non-treated OMVs. All the results presented here point out therelevance of OMVs integrity in their immunogenic capacity.