title: Polyfunctional CD4+ T cell responses to a set of pathogenic arenaviruses provide broad population coverage.
abstract: 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.
authors.affiliation: Division of Vaccine Discovery, La Jolla Institute for Allergy and Immunology, 9420 Athena Circle, La Jolla, California, 92037 USA. maya@liai.org.
authors.forename: Maya F
authors.initials: MF
authors.lastname: Kotturi
authors.forename: Jason
authors.initials: J
authors.lastname: Botten
authors.forename: Matt
authors.initials: M
authors.lastname: Maybeno
authors.forename: John
authors.initials: J
authors.lastname: Sidney
authors.forename: Jean
authors.initials: J
authors.lastname: Glenn
authors.forename: Huynh-Hoa
authors.initials: HH
authors.lastname: Bui
authors.forename: Carla
authors.initials: C
authors.lastname: Oseroff
authors.forename: Shane
authors.initials: S
authors.lastname: Crotty
authors.forename: Bjoern
authors.initials: B
authors.lastname: Peters
authors.forename: Howard
authors.initials: H
authors.lastname: Grey
authors.forename: Daniel M
authors.initials: DM
authors.lastname: Altmann
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Buchmeier
authors.forename: Alessandro
authors.initials: A
authors.lastname: Sette