Adjuvant formulations for virus-like particle (VLP) based vaccines.

The development of virus-like particle (VLP) technology has had an enormous impact on modern vaccinology. In order to optimize the efficacy and safety of VLP-based vaccines, adjuvants are included in most vaccine formulations. To date, most licensed VLP-based vaccines utilize the classic aluminum adjuvant compositions. Certain challenging pathogens and weak immune responder subjects may require further optimization of the adjuvant formulation to maximize the magnitude and duration of the protective immunity. Indeed, novel classes of adjuvants such as liposomes, agonists of pathogen recognition receptors, polymeric particles, emulsions, cytokines and bacterial toxins, can be used to further improve the immunostimulatory activity of a VLP-based vaccine. This review describes the current advances in adjuvant technology for VLP-based vaccines directed at viral diseases, and discusses the basic principles for designing adjuvant formulations for enhancing the vaccine immunogenicity.