Immunoproteomic identification of polyvalent vaccine candidates from Vibrio parahaemolyticus outer membrane proteins.

Bacterium is still a major cause of many infectious diseases and a global threat to human health, aquaculture, and animal feeding. Prevention by vaccination is the most efficient and economical way of fighting bacterial diseases, but one of the persistent challenges to prevent bacterial infections and disease transmissions is the existence of multiple bacterial species, families, and genera and the lack of efficient polyvalent vaccines against them. The information on candidate immunogens for polyvalent vaccine development is elusive, as well. For the development of broad cross-protective vaccines, we have employed heterogeneous antiserum-based immunoproteomics approaches to identify antigenically similar outer membrane (OM) proteins that could be used as potential polyvalent vaccine candidates against Vibrio parahaemolyticus , V. alginolyticus , V. fluvialis , Aeromonas hydrophila , and A. sobria infections. VPA1435, VP0764, VPA1186, VP1061, and VP2850 could be recognized by at least three antisera and demonstrated significantly passive and active immune protection against V. parahaemolyticus infection in a crucian carp model. VP1061 and VP2850 induced higher immune and protective abilities than the other three OM proteins. Furthermore, the abilities of VP1061 and VP2850 in the generation of broad cross-protective immune reaction against the infections of V. alginolyticus , A. hydrophila , and Pseudomonas fluorescens were also investigated in fish and mouse models. Our results suggested that VP1061 and VP2850 could potentially be used as polyvalent vaccine candidates for the development of novel polyvalent vaccines against V. parahaemolyticus and other Gram-negative pathogens. On the basis of these results, characteristics of OM proteins as polyvalent vaccine candidates have been addressed.

Identification of broad cross-protective immunogens using heterogeneous antiserum-based immunoproteomic approach.

Bacterium is still one of the major causes of life-threatening microbial infections. The most effective way to control bacterial infections is probably vaccine prevention. However, development of bacterial vaccine, especially polyvalent vaccines that could be used to fight against a variety of bacterial serotypes and species, is challenging due to the difficulty in identifying broad cross-protective antigens for different serotypes and species of pathogenic bacteria. In the present study, we developed a new approach to identify polyvalent vaccine candidates from outer membrane (OM) proteins of Vibrio alginolyticus with the ability to fight against infections caused by different genera and families of Gram-negative bacteria. This approach combined heterogeneous antiserum-based immunoproteomics with bacterial immunization challenging method. Four of the 35 protein spots resolved in a 2-DE gel of V. alginolyticus sarcosine-insoluble fraction could be recognized not only by homogeneous antiserum, but also by heterogeneous antisera obtained from other bacterial species, genera and families. The genes encoding the four OM proteins were then cloned and expressed in E. coli BL21. The expressed recombinant proteins were used as broadly cross-protective immunogens to immunize carps for investigation of their cross-protective spectra, activities and protective abilities in carps. The carps immunized with OmpA (VA0764) and Pal (VA1061) have abilities to fight against infections not only caused by V. alginolyticus, but also by Aeromonas hydrophila and Pseudomonas fluorescens. This study provides a novel approach for the identification of broadly cross-protective antigens, and possibly polyvalent vaccines against a variety of microbial infections.