Influence of adjuvant formulation on the induced protection of mice immunized with total soluble antigen of Trichinella spiralis.

Vaccination of pigs against the helminth nematode Trichinella could be a good alternative to prevent the risk of human infection. In order to develop an efficient and safe vaccine, the choice of the adjuvant is an important issue. In this study, two adjuvants were selected to prepare vaccines based on total soluble Trichinella spiralis muscle larvae (ML) antigen: Montanide ISA 70 water in oil emulsion and Montanide IMS nanoparticles. Aluminium hydroxide was used as a reference adjuvant. The immune response was checked by ELISA of parasite antigen specific IgG1 and IgE. Finally, protection induced in vaccinated mice was measured after a T. spiralis challenge by counting ML burdens. The results clearly showed an impact of adjuvants on the specific IgG1 and IgE antibody responses against T. spiralis. Differences were observed between the rates of protection induced according to the type of formulation, although the three adjuvants tested were able to enhance the humoral immune response. This work demonstrated the need to use an adjuvant to obtain a specific IgG1 and IgE responses directed against the total soluble extract of T. spiralis.

Montanide ISA 720 and 51: a new generation of water in oil emulsions as adjuvants for human vaccines.

The development of adjuvants will represent a major challenge for this century. Indeed the need for safer vaccines leads to the development of a new generation of antigens like synthetic peptide, recombinant proteins or even vectored DNA. However, this is to the detriment of their immunogenicity. The addition of adjuvant is becomes necessary to enhance immune responses and improve vaccine potency. However, adjuvants can be responsible for the apparition of secondary reactions and they must be adapted according to various criteria such as the route of immunization, the type of the immune response, the duration of immunity, or the quality of the antigen, in order to get the best balance between efficacy and safety.

The use of oil adjuvants in therapeutic vaccines.

Water in oil emulsions represents one of the new promising generations of adjuvants for immunotherapy. Fifty years ago, incomplete freund adjuvant (IFA) has been used in clinical trials for prophylactic vaccines like poliomyelitis or flu vaccine because of its strong potency. However, even if the quality of the raw materials has been improved in order to avoid secondary reactions, the risk benefit ratio was not favorable to its use for prophylactic vaccines. Moreover, emulsions were highly viscous with a weak stability. The development of new adjuvants concepts like liposomes, oil in water emulsions, bacterial immunostimulating compounds has induced a loss of interest for such formulations. The emergence of immunotherapy treatments for cancer, AIDS or other diseases leads to the re-emergence of these adjuvants, as the risk benefit ratio is more favorable. Then, safety of these adjuvants has been improved by the use of more specific surfactants and refined oils but also by improving their manufacturing process, allowing even sometimes their use in clinical trials for prophylactic vaccines.