Preparation, characterization and in vivo evaluation of alginate-coated chitosan and trimethylchitosan nanoparticles loaded with PR8 influenza virus for nasal immunization

For efficient mucosal vaccine delivery, nanoparticulate antigens are better taken by microfold cells in the nasal associated lymphoid tissue and also dendritic cells. Nanoparticles based on polymers such as chitosan(CHT) and its water soluble derivative, trimethylchitosan(TMC), could be successfully used as carrier/adjuvant for this purpose. Sodium alginate, a negatively charged biopolymer, could modify the immunostimulatory properties of CHT and TMC NPs and increase their stability. Sodium alginate(ALG)-coated chitosan(CHT)and trimethylchitosan(TMC) nanoparticles(NPs) loaded with inactivated PR8 influenza virus were successfully prepared by direct coating of the virus with CHT or TMC polymers to evaluate their immunoadjuvant potential after nasal immunization. After nasal immunizations in BALB/c mice, PR8-CHT formulation elicited higher IgG2 a and Ig G1 antibody titers compared with PR8-TMC. ALG coating of this formulation(PR8-CHT-ALG) significantly decreased the antibody titers and a less immune response was induced than PR8-TMC-ALG formulation. PR8-TMC-ALG formulation showed significantly higher Ig G2 a/Ig G1 ratio, as criteria for Th1-type immune response, compared with PR8-CHT-ALG and PR8 virus alone. Altogether, the PR8-TMC-ALG formulation could be considered as an efficient intranasal antigen delivery system for nasal vaccines.

HspX protein as a candidate vaccine against Mycobacterium tuberculosis： an overview

BACKGROUND： Tuberculosis （TB） is a contagious infectious disease caused by Mycobacterium tuberculosis （Mtb）. This disease with two million deaths per year has the highest mortality rate among bacterial infections. The only available vaccine against TB is BCG vaccine. BCG is an effective vaccine against TB in childhood, however, due to some limitations, has not proper efficiency in adults. Also, BCG cannot produce an adequately protective response against reactivation of latent infections. OBJECTIVE： In the present study we will review the most recent findings about contribution of HspX protein in the vaccines against tuberculosis. METHODS： Therefore, many attempts have been made to improve BCG or to find its replacement. Most of the subunit vaccines for TB in various phases of clinical trials were constructed as prophylactic vaccines using Mtb proteins expressed in the replicating stage. These vaccines might prevent active TB but not reactivation of latent tuberculosis infection （LTBI）. A literature search was performed on various online databases （PubMed, Scopus, and Google Scholar） regarding the roles of HspX protein in tuberculosis vaccines. RESULTS： Ideal subunit post-exposure vaccines should target all forms of TB infection, including active symptomatic and dormant （latent） asymptomatic forms. Among these subunit vaccines, HspX is the most important latent phase antigen of M. tuberculosis with a strong immunological response. There are many studies that have evaluated the immunogenicity of this protein to improve TB vaccine. CONCLUSION： According to the studies, HspX protein is a good candidate for development of subunit vaccines against TB infection.