Sonya L. Cyr

A nasal Proteosome influenza vaccine containing baculovirus-derived hemagglutinin induces protective mucosal and systemic immunity.

The potential for enhancing the immunogenicity of recombinant (baculovirus-derived) influenza hemagglutinin (rHA) was investigated by comparing the immune responses elicited in mice by an intranasal (i.n.) rHA formulated with Proteosomes, with those induced by intramuscular (i.m.) or i.n. rHA alone. The Proteosome-rHA vaccine induced mucosal responses in the respiratory tract, as well as high serum IgG and hemagglutination inhibition (HAI) titers. In contrast, rHA alone given i.m. induced serum IgG without mucosal responses and was ineffective at inducing either mucosal or systemic responses when given i.n. Only mice immunized with the Proteosome-rHA vaccine were completely protected from both death and acute morbidity following live virus challenge, indicating that the i.n. Proteosome-rHA vaccine induced more complete protective immunity than the same doses of unformulated rHA given i.n. or i.m.

TLR4 and MyD88 control protection and pulmonary granulocytic recruitment in a murine intranasal RSV immunization and challenge model

An intranasal vaccine composed of Toll-like receptor 2 (TLR2) ligand Neisseria meningitidis outer membrane proteins and Toll-like receptor 4 (TLR4) ligand Shigella flexneri lipopolysaccharide (LPS) (Protollin) and enriched respiratory syncytial virus (RSV) proteins (eRSV) has been demonstrated to promote balanced Th1/Th2 responses without eosinophil recruitment and to protect against challenge in mouse models. We used TLR2, TLR4 and myeloid differentiation factor 88 (MyD88) knock-out (-/-) mice to investigate the roles of these signalling pathways on immunogenicity, protection and pulmonary infiltrates following RSV immunization and challenge. Antigen-specific systemic and mucosal antibody production was significantly impaired only in TLR4-/- mice following Protollin-eRSV immunization. In contrast, an intact MyD88 pathway was crucial to elicit a balanced type 1:type 2 immune response, characterized by increased splenocyte production of antigen-induced IFNgamma and IL-10 with concomitant reduction of IL5, IgG2a isotype switching and abrogation of pulmonary eosinophil recruitment following challenge. MyD88-dependent signalling also contributed to neutrophil recruitment to the lungs following immunization with eRSV antigen, in the presence or absence of Protollin, compared to a mock antigen or vaccine. Both TLR4 and MyD88-signalling were required for optimal protection against challenge. The upregulation of early signalling molecules IFN-beta, TNFalpha, CD40 and CD86 were studied in splenocytes isolated from naïve TLR2, TLR4 and MyD88-/- mice following stimulation with vaccine components. Splenocytes from TLR4-/- mice displayed reduced IFN-beta while those of MyD88-/- mice elicited less TNFalpha and lower expression of CD40 and CD86 on CD11c+ cells. Together, our results suggest that optimal immunogenicity and protection against RSV without risk of enhanced pulmonary inflammation requires intact TLR4/MyD88-dependent signalling.