Research progress of new vaccine adjuvants / 生物工程学报

In recent years, the development of new vaccines such as nucleic acid vaccines, genetically engineered vaccines, and synthetic peptide vaccines has achieved rapid development. However, compared with traditional inactivated or live vaccines, these vaccines often have problems such as poor immunogenicity. Therefore, an adjuvant is needed to enhance its effect, and adjuvants have proven to be a key component in vaccines. There are many types of adjuvants, while currently no unified standard for the classification. At present, the most commonly used adjuvants are Aluminum adjuvant and Freund's adjuvant, but new generation vaccines will probably need new generation adjuvants. Thus, this review aims to showcase the current status of immune adjuvants, with the focus on immunomodulatory molecular adjuvant, antigen delivery adjuvant and compound adjuvant. This review provides new insights for the development of novel vaccine adjuvants.

Microfold cells-targeting antigen delivery: a promising strategy to enhance the efficacy of mucosal vaccines / 生物工程学报

The mucosae represent the first line of defense against the invasion of most pathogens, and the mucosal immune system plays a crucial role in the control of infection. Mucosal vaccination can trigger both humoral and cell-mediated immune responses mucosally as well as systemically. Hence, protective immune responses can be elicited effectively by mucosal vaccination. Microfold (M) cells being unique to the mucosal immune system can take up luminal antigens and initiating antigen-specific immune responses. The number of antigen uptake by M cells is directly related to the immune efficacy of mucosal vaccines. Utilizing M cell ligands, M cells-targeting antigen delivery can achieve highly effective mucosal immune responses. The strategy of targeted delivery of antigens to M cells and its applications can be used for the improvement of mucosal immune responses and the development of mucosal vaccines. Despite these efforts, successful development of safe and effective mucosal vaccines remains a big challenge and needs a long way to go, and provably still resort to further researches on cellular properties and functions as well as mucosal immune mechanisms.

Preparation and in vitro characterization of chitosan nanoparticles containing Mesobuthus eupeus scorpion venom as an antigen delivery system

Hydrophilic nanoparticles have been widely investigated in recent years as delivery systems for therapeutic macromolecules such as antigens. In the present study Mesobuthus eupeus venom-loaded chitosan nanoparticles were prepared via ionic gelation of tripolyphosphate (TPP) and chitosan. The optimum encapsulation efficiency (91.1 percent) and loading capacity (76.3 percent) were obtained by a chitosan concentration of 2 mg/mL, chitosan-to-TPP mass ratio of 2 and M. eupeus venom concentration of 500 µg/mL. The average nanoparticle size at optimum conditions was determined by Zetasizer (Malvern Instruments, UK). The nanoparticle size was about 370 nm (polydispersity index: 0.429) while the zeta potential was positive. Transmission electron microscope (TEM) imaging showed a spherical, smooth and almost homogenous structure for nanoparticles. Fourier transform infrared (FTIR) spectroscopy confirmed tripolyphosphoric groups of TPP linked with ammonium groups of chitosan in the nanoparticles. The in vitro release of nanoparticles showed an initial burst release of approximately 60 percent in the first ten hours, followed by a slow and much reduced additional release for about 60 hours. It is suggested that the chitosan nanoparticles fabricated in our study may provide a suitable alternative to traditional adjuvant systems.(AU)

Virosome vaccines and their application in cancer immunotherapy

Background: An increasing number of tumor associated antigens (TAA) capable of inducing immune responses have been identified in the last two decades. Unfortunately, they are weak immunogens and require potent adjuvants to promote their immunogenicity. Virosomes, nano-lipid vesicles containing viral protein spikes, have been proven amenable for transferring antigen (Ag) to the major histocompatibility complex (MHC) class I processing pathway with the aim to prime cytotoxic T-ymphocytes (CTL) responses. Objective: This mini-review outlines the virosomes platform, ranging from virosomal preparation, their intracellular trafficking and mechanism of action. Methods: The review is directed toward an application of virosomes as a novel and potential vaccine adjuvant in active cancer immunotherapy. Results and conclusion: Virosomes have been proven to be a suitable TAA delivery carrier. Ag encapsulated inside the lumen of virosomes could be prevented from serum- and cell-associated peptidases. Virosomes also facilitated the intracellular trafficking of encapsulated Ag, in which Ag could reach the cytosol and be presented by the MHC-Class I machinery. In addition, virosomes with TAA encapsulated are amenable to be a novel tumor immunotherapeutic strategy.

Progress in Mucosal Adjuvants / 中国生物工程杂志

Mucosal adjuvants play important roles in vaccine development. By now, the common used mucosal adjuvants can be divided into three categories: the bacterial derivatives, cytokines and chemokines, and antigen delivery systems. Progresses of the three kinds of adjuvants were reviewed to give a reference to novel vaccine research.