Abstract Lumazine synthase from Brucella spp. (BLS) is a highly immunogenic decameric protein. It is possible to insert foreign peptides or proteins at its ten-amino acid termini. These chimeras elicit systemic and oral immunity without adjuvants, which a

BERGUER, P; ALZOGARAY VANINA; ROSSI, ANDRES HUGO; MUNDIÑANO ,J; PIAZZON, I; GOLDBAUM, FERNANDO

PLOS ONE

PUBLIC LIBRARY SCIENCE

Lugar: San Francisco; Año: 2012

1932-6203

Lumazine synthase from Brucella spp. (BLS) is a highly immunogenic decamericprotein. It is possible to insert foreign peptides or proteins at its ten-amino acid termini. Thesechimeras elicit systemic and oral immunity without adjuvants, which are commonly needed inthe formulation of subunit-based vaccines. Here, we show that BLS induces the crosspresentation of a covalently attached peptide OVA257-264 and a specific cytotoxic response tothis peptide in the absence of adjuvants. Unlike other subunit-based vaccines, this chimerainduces rapid activation of CTLs and a specific cytotoxic response, making this polymericprotein an ideal antigen carrier for vaccine development. Adoptive transfer of transgenic OT-IT cells revealed efficient cross presentation of BLS-OVA257-264 in vivo. BLS-OVA257-264immunization induced the proliferation of OVA257-264-specific CD8+ lymphocytes and alsoincreased the percentage of OVA257-264-specific CD8+ cells expressing the early activationmarker CD69; after 5 days, the percentage of OVA257-264-specific CD8+ cells expressing highlevels of CD44 increased. This cell subpopulation showed decreased expression of IL-7Rα,indicating that BLS-OVA257-264 induced the generation of CD8+ effector cells. BLS-OVA257-264was cross presented in vitro independently of the presence of a functional TLR4 in the DCs.Finally, we show that immunization of wild type mice with the chimera BLS-OVA257-264without adjuvants induced a strong OVA257-264-specific effector cytotoxic response. Thiscytotoxicity is dependent on TLR4 as is not induced in mice lacking a functional receptor.These data show that TLR4 signaling is necesary for the induction of a cytotoxic response butnot for antigen cross presentation.