ABSTRACT.Trumenba (bivalent rLP2086) is a vaccine licensed for the prevention of meningococcal meningitis disease caused by Neisseria meningitidis serogroup B (NmB) in individuals 10-25 years of age in the USA. The vaccine is composed of two factor H binding protein (fHbp) variants that were recombinantly expressed in Escherichia coli as native lipoproteins: rLP2086-A05 and rLP2086-B01. The vaccine was shown to induce potent bactericidal antibodies against a broad range of NmB isolates expressing fHbp that were different in sequence from the fHbp vaccine antigens. Here, we describe the characterization of the vaccine antigens including the elucidation of their structure which is characterized by two distinct motifs, the polypeptide domain and the N-terminal lipid moiety. In the vaccine formulation, the lipoproteins self-associate to form micelles driven by the hydrophobicity of the lipids and limited by the size of the folded polypeptides. The micelles help to increase the structural stability of the lipoproteins in the absence of bacterial cell walls. Analysis of the lipoproteins in Toll-like receptor (TLR) activation assays revealed their TLR2 agonist activity. This activity was lost with removal of the O-linked fatty acids, similar to removal of all lipids, demonstrating that this moiety plays an adjuvant role in immune activation. The thorough understanding of the structure and function of each moiety of the lipoproteins, as well as their relationship, lays the foundation for identifying critical parameters to guide vaccine development and manufacture.

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A recent isolate of Eimeria praecox, strain G, was obtained from Georgia and purified. Studies of the life history, pathogenicity, and cross-immunity of the isolate were conducted to verify its identity. In inoculated three-week-old chickens, the occurrence of merogony and gametogony was limited to the superficial epithelium of the upper intestine. Oocysts, 23 x 19.5 microns, with a shape index of 1.17 were first observed 83 h after inoculation. Mortality and morbidity were not observed in any of the experimental birds. However, there was a positive correlation between dose of oocysts, reduced weight gain, and the incidence of exudative diathesis. These studies showed that E. praecox depresses weight gains in chickens and may be of economic importance. Although complete immunity to avian coccidiosis is believed to be species specific, chickens immune to E. praecox (G) or E. acervulina had a degree of cross-immunity to a heterologous challenge. Electrophoretic analysis of glucose phosphate isomerase and lactate dehydrogenase prepared from the European strain of E. praecox and E. praecox (G) showed no differences, confirming the identity of the isolate as E. praecox.

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The serial passage of 3 strains of Eimeria from the chicken in embryonating turkey embryos is reported here. All 3 strains increased their reproduction in turkey embryos; reproduction being equal to or better than the same lines maintained in chicken embryos. Pathogenicity and immunogenicity trials conducted in chickens using these 3 strains of Eimeria showed that all 3 turkey embryo-adapted lines were significantly less pathogenic than the parent lines. Only 1 of the lines (E. tenella (PS) turkey embryo-adapted) maintained its immunogenic potential.