A CTB-SARS-CoV-2-ACE-2 RBD Mucosal Vaccine Protects Against Coronavirus Infection

Size effect of mesoporous silica nanoparticles on regulating the immune effect of oral influenza split vaccine

Mucosal immunization is a powerful weapon against viral infection. In this paper, large pore mesoporous silica nanoparticles (LMSN) with different particle sizes were synthesized for loading influenza split vaccine (SV) to explore the effect of nanoparticle sizes on mucosal immunization and adjuvant efficacy. Interestingly, it was found that among the three particle sizes of nanoparticles, only LMSN-M with around 250 nm could significantly enhance the mucosal immune effect of SV, possessing adjuvant effect. The results indicated that particle size affected the adjuvant effect of LMSN. There was no apparent difference in vaccine loading capacity of LMSN with different particle sizes, but the release of SV depended on the pore length of LMSN. The adjuvant effect of LMSN-M was attributed to its higher cellular uptake performance, intestine absorption and transport efficiency, and the ability to stimulate the maturation of dendritic cells. Simultaneously, compared with LMSN-S and LMSN-L, the more retention of LMSN-M in mesenteric lymph nodes increased the chance of interaction between vaccine and immune system, resulting in the enhanced immunity. This is the first time to study the impact of particle size of LMSN adjuvant on improving mucosal immunity of oral influenza vaccine, and the present work provides a scientific reference for adjuvant design of oral vaccine.

Vaccine Strategies to Elicit Mucosal Immunity

Vaccines are essential tools to prevent infection and control transmission of infectious diseases that threaten public health. Most infectious agents enter their hosts across mucosal surfaces, which make up key first lines of host defense against pathogens. Mucosal immune responses play critical roles in host immune defense to provide durable and better recall responses. Substantial attention has been focused on developing effective mucosal vaccines to elicit robust localized and systemic immune responses by administration via mucosal routes. Mucosal vaccines that elicit effective immune responses yield protection superior to parenterally delivered vaccines. Beyond their valuable immunogenicity, mucosal vaccines can be less expensive and easier to administer without a need for injection materials and more highly trained personnel. However, developing effective mucosal vaccines faces many challenges, and much effort has been directed at their development. In this article, we review the history of mucosal vaccine development and present an overview of mucosal compartment biology and the roles that mucosal immunity plays in defending against infection, knowledge that has helped inform mucosal vaccine development. We explore new progress in mucosal vaccine design and optimization and novel approaches created to improve the efficacy and safety of mucosal vaccines.