Breadth of the CD4+ T cell response to Anaplasma marginale VirB9-1, VirB9-2 and VirB10 and MHC class II DR and DQ restriction elements

MHC class II molecules influence antigen-specific CD4(+) T-lymphocyte responses primed by immunization and infection. CD4(+) T-cell responses are important for controlling infection by many bacterial pathogens including Anaplasma marginale, and are observed in cattle immunized with the protective A. marginale outer membrane (OM) vaccine. Immunogenic proteins that comprise the protective OM vaccine include type IV secretion system (T4SS) proteins VirB9-1, VirB9-2, and VirB10, candidates for inclusion in a multi-epitope vaccine. Our goal was to determine the breadth of the VirB9-1, VirB9-2, and VirB10 T-cell response and MHC class II restriction elements in six cattle with different MHC class II haplotypes, defined by DRB3, DQA, and DQB allele combinations for each animal. Overlapping peptides spanning each T4SS protein were tested in T-cell proliferation assays with autologous antigen presenting cells (APC) and artificial APC expressing combinations of bovine DR and DQ molecules. Twenty immunostimulatory peptides were identified; three representing two or more epitopes in VirB9-1, ten representing eight or more epitopes in VirB9-2, and seven representing seven or more epitopes in VirB10. Of eight DRA/DRB3 molecules, four presented 15 peptides, which was biased as DRA/DRB3*1201 presented ten and DRA/DRB3*1101 presented four peptides. Four DQA/DQB molecules composed of two intrahaplotype and two interhaplotype pairs presented seven peptides, of which five were uniquely presented by DQ molecules. In addition,three functional mixed isotype (DQA/DRB3) restriction elements were identified. The immunogenicity and broad MHC class II presentation of multiple VirB9-1, VirB9-2, and VirB10 peptide epitopes justify their testing as a multi-epitope vaccine against A. marginale

A Bang into nowhere: Comments on the Universe Expansion Theory

Anaplasma marginale is the most prevalent tick-borne livestock pathogen and poses a significant threat to cattle industry. In contrast to currently available live blood-derived vaccines against A. marginale, alternative safer and better-defined subunit vaccines will be of great significance. Two proteins (VirB9-1 and VirB9-2) from the Type IV secretion system of A. marginale have been shown to induce humoral and cellular immunity. In this study, Escherichia coli were used to express VirB9-1 and VirB9-2 proteins. Silica vesicles having a thin wall of 6 nm and pore size of 5.8 nm were used as the carrier and adjuvant to deliver these two antigens both as individual or mixed nano-formulations. High loading capacity was achieved for both proteins, and the mouse immunisation trial with individual as well as mixed nano-formulations showed high levels of antibody titres over 107 and strong T-cell responses. The mixed nano-formulation also stimulated high-level recall responses in bovine T-cell proliferation assays. These results open a promising path towards the development of efficient A. marginale vaccines and provide better understanding on the role of silica vesicles to deliver multivalent vaccines as mixed nano-formulations able to activate both B-cell and T-cell immunity, for improved animal health