Vaccines adjuvants

Abstract

A wide variety of adjuvant-active materials have been used in experimental and veterinary vaccines but the only commonly used adjuvants for human vaccines are based on aluminium salts. The reasons for this are numerous but most new adjuvant products have failed in the developmental stage due to toxicity or limitations associated with manufacturing and stability. Research completed over the last 30 years is now providing products with significant potential for improving the efficacy of human vaccines. These new products are derived from many different sources, including natural products, such as plant saponins, bacterial lipopolysaccharides, biodegradable oils and lipids, and novel synthetic polymers. Individual adjuvants exert varied effects on the immune system and many products can be used in combination formulations. This degree of flexibility will allow for vaccines to be optimally formulated for specific disease targets. The ability to produce more potent vaccines, through the use of adjuvants, is critical to the expansion of this field, especially for vaccines targeting pathogens where no form of protection exists. Examples of pathogen targets used most commonly to clinically evaluate new adjuvant technologies include HIV-1 and the causative agent of human malaria, Plasmodium falciparum. Adjuvants may also provide significant benefit to those segments of the population that are partially immunocompromised, such as the elderly. Finally, highly potent adjuvant-supplemented vaccines have shown promise as therapeutics for the treatment of cancer; products that can be used to supplement established therapies. Descriptions of the advantages and limitations of adjuvants that are most likely to be available for use as components in licensed vaccines within the next decade have been included in this review.