Because of their large surface area and immunological competence, mucosal tissues are attractive administration and target sites for vaccination. An important characteristic of mucosal vaccination is its ability to elicit local immune responses, which act against infection at the site of pathogen entry. However, mucosal surfaces are endowed with potent and sophisticated tolerance mechanisms to prevent the immune system from overreacting to the many environmental antigens. Hence, mucosal vaccination may suppress the immune system instead of induce a protective immune response. Therefore, mucosal adjuvants and/or special antigen delivery systems as well as appropriate dosage forms are required in order to develop potent mucosal vaccines. Whereas oral, nasal and pulmonary vaccine delivery strategies have been described extensively, the sublingual and buccal routes have received considerably less attention. In this review, the characteristics of and approaches for sublingual and buccal vaccine delivery are described and compared with other mucosal vaccine delivery sites. We discuss recent progress and highlight promising developments in the search for vaccine formulations, including adjuvants and suitable dosage forms, which are likely critical for designing a successful sublingual or buccal vaccine. Finally, we outline the challenges, hurdles to overcome and formulation issues relevant for sublingual or buccal vaccine delivery.

We successfully developed a hollow microneedle technology for dermal vaccination that enables fundamental research on factors, such as insertion depth and volume, and insertion angle, on the immune response.

PurposeThe aim of current study was to develop a dried inactivated polio vaccine (IPV) formulation with minimal loss during the drying process and improved stability when compared with the conventional liquid IPV.MethodsExtensive excipient screening was combined with the use of a Design of Experiment (DoE) approach in order to achieve optimal results with high probability.ResultsAlthough it was shown earlier that the lyophilization of a trivalent IPV while conserving its antigenicity is challenging, we were able to develop a formulation that showed minimal loss of potency during drying and subsequent storage at higher temperatures.ConclusionThis study showed the potential of a highly stable and safe lyophilized polio vaccine, which might be used in developing countries without the need of a cold-chain.Electronic supplementary materialThe online version of this article (doi:10.1007/s11095-014-1359-6) contains supplementary material, which is available to authorized users.

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In the near future oral polio vaccine (OPV) will be replaced by inactivated polio vaccine (IPV) as part of the eradication program of polio. For that reason, there is a need for substantial amount of safe and more affordable IPV for low-income countries. Bioneedles, which are biodegradable mini-implants, have the potential to deliver vaccines outside the cold-chain and administer them without the use of needles and syringes. In the current study, Bioneedles were filled with IPV, subsequently lyophilized, and antigenic recoveries were determined both directly after IPV-Bioneedle preparation as well as after elevated stability testing. Further, we assessed the immunogenicity of IPV-Bioneedles in rats and the residence time at the site of administration. Trivalent IPV was formulated in Bioneedles with recoveries of 101±10%, 113±18%, and 92±15%, respectively for serotypes 1, 2 and 3. IPV in Bioneedles is more resistant to elevated temperatures than liquid IPV: liquid IPV retained less than half of its antigenicity after 1 day at 45°C and IPV in Bioneedles showed remaining recoveries of 80±10%, 85±4% and 63±4% for the three serotypes. In vivo imaging revealed that IPV administered via Bioneedles as well as subcutaneously injected liquid IPV showed a retention time of 3 days at the site of administration. Finally, an immunogenicity study showed that IPV-filled Bioneedles are able to induce virus-neutralizing antibody titers similar to those obtained by liquid intramuscular injection when administered in a booster regime. The addition of LPS-derivate PagL in IPV-filled Bioneedles did not increase immunogenicity compared to IPV-Bioneedles without adjuvant. The current study demonstrates the pre-clinical proof of concept of IPV-filled Bioneedles as a syringe-free alternative delivery system. Further pre-clinical and clinical studies will be required to assess the feasibility whether IPV-Bioneedles show sufficient safety and efficacy, and may contribute to the efforts to eradicate and prevent polio in the future.

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Polio is on the brink of eradication. Improved inactivated polio vaccines (IPV) are needed towards complete eradication and for the use in the period thereafter. Vaccination via mucosal surfaces has important potential advantages over intramuscular injection using conventional needle and syringe, the currently used delivery method for IPV. One of them is the ability to induce both serum and mucosal immune responses: the latter may provide protection at the port of virus entry. The current study evaluated the possibilities of polio vaccination via mucosal surfaces using IPV based on attenuated Sabin strains. Mice received three immunizations with trivalent sIPV via intramuscular injection, or via the intranasal or sublingual route. The need of an adjuvant for the mucosal routes was investigated as well, by testing sIPV in combination with the mucosal adjuvant cholera toxin. Both intranasal and sublingual sIPV immunization induced systemic polio-specific serum IgG in mice that were functional as measured by poliovirus neutralization. Intranasal administration of sIPV plus adjuvant induced significant higher systemic poliovirus type 3 neutralizing antibody titers than sIPV delivered via the intramuscular route. Moreover, mucosal sIPV delivery elicited polio-specific IgA titers at different mucosal sites (IgA in saliva, fecal extracts and intestinal tissue) and IgA-producing B-cells in the spleen, where conventional intramuscular vaccination was unable to do so. However, it is likely that a mucosal adjuvant is required for sublingual vaccination. Further research on polio vaccination via sublingual mucosal route should include the search for safe and effective adjuvants, and the development of novel oral dosage forms that improve antigen uptake by oral mucosa, thereby increasing vaccine immunogenicity. This study indicates that both the intranasal and sublingual routes might be valuable approaches for use in routine vaccination or outbreak control in the period after complete OPV cessation and post-polio eradication.