Potentiating lung-localized immune responses to conserved influenza virus antigen through a novel vaccine platform

Abstract

Abstract Current influenza vaccines are primarily delivered at peripheral sites and provide immunity characterized by neutralizing antibody responses. However, this strategy often fails to provide broadly-protective immune capacity. Numerous studies have implicated lung localized T cells as key mediators of broadly protective immunity to influenza infection. The goal of our current research is to expand virus-specific CD4 T cells via the respiratory route in order to understand how this mode of priming poises the host for future protective immunity to infection. We have explored a novel nanolipoprotein (NLP) vaccine conjugated to influenza nucleocapsid protein (NP) to boost lung localized immunity. ELISA assays revealed that NLP immunization boosted anti-NP antibody titers, which have been shown to contribute to heterosubtypic immunity. Importantly, immunization with NLP elicited NP-specific CD4 and CD8 T cell responses in the lung, draining lymph node, and spleen. Intravascular labeling and flow cytometry were performed to assess the localization and phenotype of CD4 T cells in the lung. Analyses revealed that intranasal immunization with NLP elicited an increased abundance of lung parenchyma-localized CD4 T cells expressing surface markers associated with tissue residency and cytolytic potential. Using a novel pMHC class II tetramer, we observed that the majority of antigen-specific CD4 T cells were localized to the lung tissue and can rapidly produce antiviral cytokines upon restimulation. These studies will improve our understanding of vaccine strategies deigned to elicit effector T cells at mucousal sites and demonstrate the potential of tissue resident cells to mediate broadly protective immune responses to influenza.