Vaccination of mice with chitosan nanogel-associated recombinant NcPDI against challenge infection with Neospora caninum tachyzoites.

The effects of nanogel encapsulation of recombinant NcPDI (recNcPDI) following vaccination of mice by intranasal or intraperitoneal routes and challenge infection with Neospora caninum tachyzoites were investigated. Nanogels were chitosan based, with an alginate or alginate-mannose surface. None of the mice receiving recNcPDI intraperitoneal (i.p.) (without nanogels) survived, whereas intranasal (i.n.) application protected 9 of 10 mice from disease. Association of recNcPDI with nanogels improved survival of i.p. vaccinated mice, but nanogels without recNcPDI gave similar protection levels. When nanogels were inoculated via the i.n. route, 80% of the mice were protected. Association of recNcPDI with the alginate-coated nanogels protected all mice against disease. Quantification of the cerebral parasite burden showed a significant reduction of parasite numbers in most experimental groups vaccinated i.n., except those vaccinated with alginate-mannose nanogels with or without recNcPDI. For i.p. vaccinated groups, no significant differences in cerebral infection densities were measured, but there was a reduction in the groups vaccinated with recNcPDI associated with both types of nanogels. Analysis of the immune responses of infected mice indicated that association of recNcPDI with nanogels altered the patterns of cytokine mRNA expression profiles, but had no major impact on the antibody subtype responses. Nevertheless, this did not necessarily relate to the protection.

Detection of IgG and IgE serum antibodies to Culicoides salivary gland antigens in horses with insect dermal hypersensitivity (sweet itch).

We postulated that all horses exposed to the bites of Culcoides (midges) would have an antibody response to the antigen secreted in Culcoides saliva, but that IgE antibody would be restricted to allergic individuals. Using immunohistology on sections of fixed Culicoides, we have demonstrated the presence of antibodies in horse serum which recognise Culicoides salivary glands. Antibodies were detected in the serum of horses with insect dermal hypersensitivity and in the serum of normal horses exposed to Culicoides bites. In contrast, no antibodies were detected in serum from native Icelandic ponies which had not been exposed to Culicoides. Anti-salivary gland IgG antibodies were detected in serum from both allergic and healthy horses exposed to Culicoides. IgE antibodies were only detected in horses with signs of insect dermal hypersensitivity, they were not found in serum of healthy controls nor in the serum of horses with a history of hypersensitivity but in remission at the time of sampling. Using western blotting we confirmed the presence of antibodies to Culicoides antigens and demonstrated that individual horses react to different numbers of antigens. This paper demonstrates the ability of serum from allergic horses to detect Culcoides antigens and will enable further studies to isolate and characterise the allergens.

Nanogel vaccines targeting dendritic cells: contributions of the surface decoration and vaccine cargo on cell targeting and activation.

Dendritic cells (DCs) play crucial roles in initiating and promoting immune defences, providing a pivotal target for vaccines. Although nanoparticle/nanogel-based delivery vehicles are showing potential for delivering vaccines to the immune system, there is little information on their characteristics of interaction with DCs. While particle uptake by DCs has been shown, the mechanism of cell targeting has not been studied. Moreover, it is still unclear how particle surface decoration influences the handling of such vaccines by DCs. Accordingly, chitosan nanogels carrying a model antigen, ovalbumin (ova), were analysed for interaction with and processing by DCs. Nanogel surfaces decorated with alginate (alg) or mannosylated alginate (alg-man), were used for targeting particular DC receptors. DC uptake of particles was observed, being dependent on endosomal-based processes. Inhibiting PI3-kinase or lipid raft activities impaired the uptake, which was only reduced, indicating the involvement of more than one endocytic pathway; notably, this was observed with both nanogel-delivered or free ova. Importantly, surface decoration of particles was less influential on particle uptake, contrasting with the ova cargo which played the major role. Such influence of the vaccine cargo has to date been largely ignored. When receptors interacting directly with ova were blocked, this altered the uptake of alg-nanogels and alg-man-nanogels carrying ova. The nanogels did have an influential role, in that modulation of DC functional activity owed more to the nanogel structure. Using an in vitro restimulation assay with ova-specific lymphocytes, nanogel-delivered and free ova were similarly effective at inducing specific antibody. Nanogel-delivered ova with mannose surface decoration was superior to free ova for inducing interferon-γ production by T-lymphocytes. Together, the data demonstrates that particle-based vaccine delivery should consider the influences of both the surface decoration and the vaccine cargo; each can influence different aspects of the interaction with DCs. Such combined influences are likely to impinge on the characteristics of the immune response induced.