The use of propolis as vaccine's adjuvant.

The success of many vaccines relies on their association with selected adjuvants in order to increase their immunogenicity and ensure long-term protection. All available adjuvants have adverse effects due to their toxicity and reactogenicity. Pre-clinical in vivo investigations can identify new natural products for further applications. Several studies have confirmed the different medicinal benefits of propolis. However the studies that addressed its use as a potent, safe, vaccine adjuvant were limited to specific countries and languages, primarily Chinese. Those studies introduced the use of different extracts and formulations of propolis as adjuvants for bacterial, viral, and parasitic vaccines. This comprehensive up-to-date review categorizes, documents, and discusses those trials in a clear chronological manner.