2C and D). hierarchy, and epitope-specific CD8+ T cell requirements for co-stimulation that all influence the immune response magnitude. The unique effect of TLR agonists on neonatal T cell reactions is definitely important to consider for RSV vaccines designed for young infants. Intro Globally, lower respiratory tract infections are the largest contributor to mortality in the 1st year of existence (1). Viral infections cause 50% of this mortality, with RSV becoming the single most important viral pathogen followed by influenza (1). Immunity to viral illness requires clearance of infected cells by CD8+ cytotoxic T lymphocytes (CTL), and in young infants, the appearance of CD8+ T cells correlates with the time of recovery and convalescence (2, 3). The highly regulated immune environment of the neonate has been implicated in limiting robust CD8+ T cell reactions, thus playing a role in susceptibility to viral illness (4C6). Neonatal humans and mice, however, have been found to mount more adult-like T cell reactions in the establishing of infections, such as human being cytomegalovirus or Trypanozoma cruzi (7, 8), and after particular immunizations or stimuli (9C11). These studies implicate a role for innate signaling to override the limitations of pathogen-specific CD8+ T cell reactions in young infants. Following main illness, CD8+ T cell activation happens in the lymph nodes draining the site of illness upon encountering antigenic peptide offered in the context of a MHC class I (MHCI) molecule in conjunction with accessory signaling (12C14). Only a tiny portion of all the potential viral epitopes are identified by na?ve epitope-specific CD8+ T cells and the magnitude of each epitope-specific response varies resulting in a numerical hierarchy with immunodominant epitopes provoking the largest CD8+ T cell reactions. Intrinsic CD8+ T cell factors such as the quantity and phenotype of na?ve pathogen-specific CD8+ T cells and the affinity of the T cell receptor (TCR) for the peptide-MHCI complex have been shown to predict the resulting immunodominance hierarchy (15C17). In addition, factors extrinsic to the T cell such as antigen availability and the affinity of peptide for the MHCI complex of APCs have been shown to GANT61 influence T Rabbit Polyclonal to MCM3 (phospho-Thr722) cell response magnitudes (18C20). We have demonstrated previously that adult CB6F1/J mice have an immunodominant response to an epitope in the M2 protein of RSV (KdM282C90, RSV transcription processivity element, amino acid residues 82C90) and a subdominant response to an epitope in GANT61 the M protein (DbM187C195, RSV matrix protein, amino acid residues 187C195) (21). Neonatal mice make a distinct response during RSV illness in which the KdM282C90 CD8+ T cell response is lower in magnitude, resulting in a codominant T cell response (22). The adult response hierarchy is definitely maintained during congenic transfer of adult CD8+ T cells into neonatal mice going through RSV illness, suggesting that intrinsic factors identified the KdM282C90-immunodominance (22). In addition, we have demonstrated that lung standard dendritic GANT61 cell (cDC) reactions are more mature upon RSV illness outside of the neonatal period and this coincides with the age-dependent transition from neonatal to adult CD8+ T cell response hierarchy (23). In mice, two cDC subsets, designated CD103+ DCs and CD11b+ DCs, take up antigen in the lung and migrate to the mediastinal lymph node that drains the lung (dLN) to present antigen to T cells (24, 25). CD103+ GANT61 DCs have been shown to be more effective at cross-presenting antigen to CD8+ T cells (25). Recent studies, however, have suggested that both CD103+ DCs and CD11b+ DCs can contribute to the quantity and quality of.