Background. Several arenaviruses cause severe hemorrhagic fever and aseptic meningitis in humans for which no licensed vaccines are available. A major obstacle for vaccine development is pathogen heterogeneity within the Arenaviridae family. Evidence in animal models and humans indicate that T cell and antibody-mediated immunity play important roles in controlling arenavirus infection and replication. Because CD4+T cells are needed for optimal CD8+T cell responses and to provide cognate help for B cells, knowledge of epitopes recognized by CD4+T cells is critical to the development of an effective vaccine strategy against arenaviruses. Thus, the goal of the present study was to define and characterize CD4+T cell responses from a broad repertoire of pathogenic arenaviruses (including lymphocytic choriomeningitis, Lassa, Guanarito, Junin, Machupo, Sabia, and Whitewater Arroyo viruses) and to provide determinants with the potential to be incorporated into a multivalent vaccine strategy. Results. By inoculating HLA-DRB1*0101 transgenic mice with a panel of recombinant vaccinia viruses, each expressing a single arenavirus antigen, we identified 37 human HLA-DRB1*0101-restricted CD4+T cell epitopes from the 7 antigenically distinct arenaviruses. We showed that the arenavirus-specific CD4+T cell epitopes are capable of eliciting T cells with a propensity to provide help and protection through CD40L and polyfunctional cytokine expression. Importantly, we demonstrated that the set of identified CD4+T cell epitopes provides broad, non-ethnically biased population coverage of all 7 arenavirus species targeted by our studies. Conclusions. The identification of CD4+T cell epitopes, with promiscuous binding properties, derived from 7 different arenavirus species will aid in the development of a T cell-based vaccine strategy with the potential to target a broad range of ethnicities within the general population and to protect against both Old and New World arenavirus infection. © 2010 Kotturi et al; licensee BioMed Central Ltd.

The contribution of HLA class II-restricted CD4 + T cell responses to HIV immune control is poorly defined. Here, we delineated previously uncharacterized peptide-DRB1 restrictions in functional assays and analyzed the host genetic effects of HLA-DRB1 alle