A polymeric protein induces specific cytotoxicity in a TLR4 dependent manner in the absence of adjuvants

BERGUER PM, ALZOGARAY VA, ROSSI AH, MUNDIÑANO J, PIAZZON I AND GOLDBAUM FA.

PLOS ONE

PUBLIC LIBRARY SCIENCE

Lugar: San Francisco; Año: 2012 vol. 7 p. 45705 - 45706

1932-6203

Lumazine synthase from Brucella spp. (BLS) is a highly immunogenic decameric protein. It is possible to insert foreignpeptides or proteins at its ten-amino acid termini. These chimeras elicit systemic and oral immunity without adjuvants,which are commonly needed in the 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 to this peptide in the absence ofadjuvants. Unlike other subunit-based vaccines, this chimera induces rapid activation of CTLs and a specific cytotoxicresponse, making this polymeric protein an ideal antigen carrier for vaccine development. Adoptive transfer of transgenicOT-I T cells revealed efficient cross presentation of BLS-OVA257–264 in vivo. BLS-OVA257–264 immunization induced theproliferation of OVA257–264-specific CD8+ lymphocytes and also increased the percentage of OVA257–264-specific CD8+ cellsexpressing the early activation marker 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-7Ra, indicating that BLS-OVA257–264induced the generation of CD8+ effector cells. BLS-OVA257–264 was cross presented in vitro independently of the presence ofa functional TLR4 in the DCs. Finally, we show that immunization of wild type mice with the chimera BLS-OVA257–264 withoutadjuvants induced a strong OVA257–264-specific effector cytotoxic response. This cytotoxicity is dependent on TLR4 as is notinduced in mice lacking a functional receptor. These data show that TLR4 signaling is necesary for the induction of acytotoxic response but not for antigen cross presentation.