In conclusion, this study showed that recombinant Etx mutant Y30A-Y196A is non-toxic to mice, demonstrating the potential of Y30A-Y196A mutant to form the basis of an improved recombinant vaccine against enterotoxemia
in ruminants. Further studies are needed to determine whether Y30A-Y196A is able to induce protection against experimental enterotoxemia in sheep. MBB and CAH carried out most of the experiments and drafted the manuscript. CAH carried out and CV assisted with the in vivo toxicity assay. SPFC, CGS, CEN and ARC helped with experiments and interpreted the data. RT, DSM and AKB designed research and revised the manuscript. All authors read and approved the final manuscript. The authors have no competing interests. We acknowledge the support of the Wellcome ERK inhibitor datasheet Trust Grant WT089618MA and the European Union Marie Curie Network grant 237942. We also thank Michel R. Popoff, Institut Pasteur for providing wild type epsilon toxin. “
“Neisseria meningitidis is a major cause of epidemics in sub-Saharan Africa . These were mainly caused by strains belonging to capsular group A, but there has been
an increasing contribution of serogroups W and X strains with epidemic potential in the last two decades , ,  and . A serogroup A polysaccharide conjugate vaccine (MenAfriVac) has been developed for preventive mass immunization in the African meningitis belt . The vaccine is highly effective at prevention of serogroup A invasive disease and carriage ,  and , but group W and X strains remain a check details persistent problem. This underlines the need for an affordable vaccine that provides protection against the
main serogroups causing meningitis in Africa and potentially against serogroups that may emerge in the region in the future. GMMA generated from strains engineered to over-express immunogenic antigens that are present across all serogroups, constitute an attractive approach to vaccination. The term GMMA (Generalised Modules for Membrane Antigens) provides a clear distinction from conventional detergent-extracted Parvulin outer membrane vesicles (dOMV), and native outer membrane vesicle (NOMV), which are released spontaneously from Gram-negative bacteria. GMMA differ in two crucial aspects from NOMV. First, to induce GMMA formation, the membrane structure has been modified by the deletion of genes encoding key structural components, including gna33 (meningococcus) and tolR (Shigella and Salmonella ). Second, as a consequence of the genetic modification, large quantities of outer membrane bud off (the Italian word for bud is ‘gemma’) to provide a practical source of membrane material for vaccine production, leading to potential cost reduction. While NOMV have been used for immunogenicity studies, the yields are too low for practical vaccines.