Vaccines are essential to prevent infectious diseases, but their thermal instability leads to their heavy reliance on cold-chain. Physical encapsulation is the simplest and most effective strategy to increase the thermostability of vaccines. However, traditional mineralized coatings are strictly dependent on the properties of substrate surface and synthesis conditions. Considering the instability and low surface charge density of vaccines, we developed a facile and robust approach for the protection of a single viral vaccine, tobacco mosaic virus (TMV), through tannic (TA) and FeIII metal-polyphenol networks, which significantly improved the thermostability of viral vaccine by strengthening its conformational rigidity. We found that the formed TA-FeIII nanoshell drastically enhanced the thermostability of the viral vaccine at high temperature of 100 °C and long-term storage at 37 °C. Additionally, the TA-FeIII nanoshell did not destroy the viral RNA, had excellent biocompatibility and was easily synthesized on the vaccine surface within seconds. This ease, low cost and substrate-independent approach makes TA-FeIII nanoshell as a potential candidate for vaccine applications.
Transdermal drug delivery has been regarded as an alternative to oral delivery and subcutaneous injection. However, needleless transdermal delivery of biomacromolecules remains a challenge. Herein, a transdermal delivery platform based on biocompatible fluorocarbon modified chitosan (FCS) is developed to achieve highly efficient non-invasive delivery of biomacromolecules including antibodies and antigens. The formed nanocomplexes exhibits effective transdermal penetration ability via both intercellular and transappendageal routes. Non-invasive transdermal delivery of immune checkpoint blockade antibodies induces stronger immune responses for melanoma in female mice and reduces systemic toxicity compared to intravenous injection. Moreover, transdermal delivery of a SARS-CoV-2 vaccine in female mice results in comparable humoral immunity as well as improved cellular immunity and immune memory compared to that achieved with subcutaneous vaccine injection. Additionally, FCS-based protein delivery systems demonstrate transdermal ability for rabbit and porcine skins. Thus, FCS-based transdermal delivery systems may provide a compelling opportunity to overcome the skin barrier for efficient transdermal delivery of bio-therapeutics.
Adjuvants including aluminum adjuvant (Alum) and oil-water emulsion have been widely used in inactivated pseudorabies virus (PRV) vaccines to improve their performance, however, they are not sufficient to protect from PRV infection because of the weak immune response and poor Th1-type immune response. Divalent manganese ion (Mn 2+ ) has been reported to increase the cellular immune response significantly. In this work, a xanthan gum and carbomer-dispersed Mn 2+ -loaded tannic acid-polyethylene glycol (TPMnXC) nanoparticle colloid is developed and used as an adjuvant to improve the performance of the inactivated PRV vaccine. The good in vitro and in vivo biocompatibility of the developed TPMnXC colloid has been confirmed by the cell viability assay, erythrocyte hemolysis, blood routine analysis, and histological analysis of mouse organs and injection site. The TPMnXC-adjuvanted inactivated PRV vaccine (TPMnXC@PRV) significantly promotes higher and more balanced immune responses indicating with an increased specific total IgG antibody and IgG2a/IgG1 ratio, efficient splenocytes proliferation, and elevated Th1- and Th2-type cytokine secretion than those of control groups. Wild PRV challenge experiment is performed using mice as a model animal, achieving a protection rate of up to 86.67 %, which is much higher than those observed from the commercial Alum. This work not only demonstrates the high potentiality of TPMnXC in practical applications but also provides a new way to develop the Mn 2+ -loaded nanoadjuvant for veterinary vaccines.
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