The development of a new combined adjuvant vector for mucosal immunization CTA1-DD/ISCOM

Sammanfattning: The CTA1-DD/ISCOMs vector is a rationally designed mucosal adjuvant that was developed to host the distinctive properties of either adjuvant alone or in a combination that hosted additive enhancing effects on mucosal immune responses. Here I demonstrate that CTA1-DD can be incorporated into the ISCOM with greatly augmented immunogenicity of both incorporated and admixed antigen. The combined vector was a highly effective enhancer of a broad range of immune responses including specific antibodies and CD4+ T cell immunity. In particular, mucosal specific IgA responses in the respiratory and the genital tracts were strongly augmented by the combined vector, a mechanism that was enzyme dependent since the presence of the enzymatically inactive CTA1R7K-DD component failed to enhance the response above that with ISCOMs alone. Antigen incorporated into the combined vector could be presented by B cells as well as dendritic cells (DC). I also found that B cells in the lymph node were indeed targeted by the combined vector, but not by ISCOMs alone. The CTA1-DD/ISCOMs vaccine vector combines properties from two distinctive adjuvant systems. The ISCOM targets DC while the CTA1-exerts ADP-ribosylating functions. Following subcutaneous injection the CTA1-DD/ISCOMs vector induced a substantial increase in the cellularity of the draining lymph node, which was particularly evident for B cells and even more for granulocytes. These effects were enzyme-dependent as the inactive mutant CTA1R7K-DD/ISCOMs did not elicit a similar pattern. Functional studies of highly enriched DC in vitro demonstrated that the combined vector was superior at stimulating pro-inflammatory cytokines and chemokines, notably IL-1β, MIP-1 and RANTES, compared with ISCOMs alone. These effects appeared not to be due to better binding/up-take of the combined vector in DC, rather they depended on an intact enzymatic activity of the CTA1-enzyme. These findings help explain which are the critical properties added by the CTA1-DD to the ISCOM adjuvant. In my final article I used an adoptive transfer system to investigate the specific induction of genital tract CD4+ T cells by using ovalbumin (OVA) as our model antigen. Transfer of OVA specific T cell receptor (TCR) transgenic CD4+ T cells to naïve normal mice allows for tracking these cells using a TCR-specific antibody, KJ.126, after immunizations with or without adjuvant vectors. I found that hormones play an important role in the priming of T cells, since estrogen-treated mice failed to respond and progesterone-treated mice greatly expanded their OVA-specific T cells following immunization. Progesterone treatment expanded the OVA-specific T cells in a dose dependent way in regional lymph nodes. I also investigated the role of local verses systemic immunization on activation of genital tract T cells and found that both vaginal and intranasal immunizations with cholera toxin conjugated to OVA (CT-OVA) strongly expanded KJ.126+ T cells in the draining lymph node (Para aortic lymph node). However, local immunization was significantly more effective and was also an absolute requirement to attract T cells to the genital tract mucosa. These results convincingly demonstrate that not only antibody responses, but also antigen-specific T cell responses are effectively primed and boosted by local genital tract immunizations.

  Denna avhandling är EVENTUELLT nedladdningsbar som PDF. Kolla denna länk för att se om den går att ladda ner.