RBF protein with MA103 adjuvant elicited protective immunity against human respiratory syncytial virus in BALB/c mice

The development of human respiratory syncytial virus (HRSV) vaccine was hampered by an enhanced respiratory disease due to Th2-biased immune response. In this study, adjuvants MA103 and aluminum phosphate (Adju-Phos) were used to verify the immunogenicity of RBF protein (F protein expressed by E. coli). Both adjuvants significantly increased the neutralizing antibody titer and the number of IFN-γ-secreting CD4+ T cells in mice. However, from the IgG1/IgG2a and IFN-γ/IL-4-secreting CD4+ T cells ratio, MA103 significantly enhanced Th1-biased immune response. The pathological damage of lung in group RBF/MA103 was slighter than that in group RBF/Adju-Phos. In addition, the HRSV copies in the lung of group RBF/MA103 decreased by approximately 3×log10. These results suggested that MA103 provided better protection in mice.

Microneedle-based two-step transdermal delivery of Langerhans cell-targeting immunoliposomes induces a Th1-biased immune response

Novel Coronavirus is affecting human's life globally and vaccines are one of the most effective ways to combat the epidemic. Transcutaneous immunization based on microneedle (MN) has attracted much attention because of its painlessness, rapidity, high efficiency and good compliance. In this study, CD11c monoclonal antibody-immunoliposomes (OVA@CD11c-ILP) actively targeting to Langerhans cells (LCs) were successfully prepared and were delivered by the microchannels of skin produced by MN to induce an immune response in vivo. OVA@CD11c-ILP could be targeted to LCs by conjugating CD11c monoclonal antibody to the surface of the ILP. OVA@CD11c-ILP promoted the maturation of dendritic cells (DCs) and the uptake and endocytosis of antigen by LCs. Moreover, OVA@CD11c-ILP immunization can significantly inhibit tumor growth and prolong overall survival. Furthermore, a higher antibody's titer ratio of IgG1/IgG2a indicated that the immune response stimulated by this immunization method was Th1-biased and the liposomes showed Th1-type adjuvant effect. In conclusion, the combination delivery system of immunoliposomes and microneedle can significantly improve the efficiency of antigen presentation and effectively activate cellular immune responses in the body, which is expected to be a promising transdermal immune strategy.

Yeast Shells Encapsulating Adjuvant AS04 as an Antigen Delivery System for a Novel Vaccine against Toxoplasma Gondii

Toxoplasma gondii (T. gondii) infection causes severe zoonotic toxoplasmosis, which threatens the safety of almost one-third of the human population globally. However, there is no effective protective vaccine against human toxoplasmosis. This necessitates anti-T. gondii vaccine development, which is a main priority of public health. In this study, we optimized the adjuvant system 04 (AS04), a vaccine adjuvant constituted by 3-O-desacyl-4'-monophosphoryl lipid A (a TLR4 agonist) and aluminum salts, by packing it within natural extracts of β-glucan particles (GPs) from Saccharomyces cerevisiae to form a GP-AS04 hybrid adjuvant system. Through a simple mixing procedure, we loaded GP-AS04 particles with the total extract (TE) of T. gondii lysate, forming a novel anti-T. gondii vaccine GP-AS04-TE. Results indicated that the hybrid adjuvant can efficiently and stably load antigens, mediate antigen delivery, facilitate the dendritic uptake of antigens, boost dendritic cell maturation and stimulation, and increase the secretion of pro-inflammatory cytokines. In the mouse inoculation model, GP-AS04-TE significantly stimulated the function of dendritic cells, induced a very strong TE-specific humoral and cellular immune response, and finally showed a strong and effective protection against toxoplasma chronic and acute infections. This work proves the potential of GP-AS04 for exploitation as a vaccine against a range of pathogens.

Aluminum hydroxide colloid vaccine encapsulated in yeast shells with enhanced humoral and cellular immune responses

Aluminum salt (Alum) is one of the most important immune adjuvants approved for use in humans, however it is not suitable for vaccination against various chronic infectious diseases and cancers for not being able to induce cell-mediated (Th1) immunity. Here, we encapsulated an Alum colloid inside β-glucan particles (GPs), which are a type of natural particles derived from the yeast glucan shells, to prepare hybrid GP-Alum (GP-Al) adjuvant particles with a very uniform size of 2-4 μm. These hybrid particles can be used to load antigen proteins through a simple mixing procedure, and can be highly specifically targeted to antigen-presenting cells (APCs) and strongly activate dendritic cells (DCs) maturation and cytokine secretion. In an animal model, they elicit a strong Th1-biased immune response and extremely high antibody titer, and cause marked prophylactic and therapeutic effects against tumors. As Alum has been proven to be a safe adjuvant to induce strong humoral responses and β-glucans are safe for human use, this very uniform hybrid Alum particulate system could have important application as a vaccine carrier to stimulate humoral and cellular immune responses at the same time.