Polysaccharides extracted from wild plants might be a new source of vaccination adjuvants. In this study, the researchers concentrated on PCP-I, a natural plant polysaccharide produced from Poria cocos, a Chinese traditional herbal remedy. They used the anthrax protective antigen (PA) as a model to assess PCP-adjuvant I’s capacity to improve the immunogenicity and protection of a PA-based anthrax vaccine. PCP-I may dramatically increase anthrax-specific anti-PA antibodies, toxin-neutralizing antibodies, anti-PA antibody affinity, and IgG1 and IgG2a levels, according to the findings.
Furthermore, PCP-I boosted the frequency of PA-specific memory B cells, the proliferation of PA-specific splenocytes, the production of IL-4, and the activation of Dendritic cells (DCs) in vitro. PCP-I and CpG substantially increased the amount of anti-PA antibodies and neutralising antibodies, notably PA-specific IgG2a, and changed the Th2-bias to a Th1/Th2 balanced response. Furthermore, PCP-I with or without CpG may considerably enhance the survival rate of vaccinated mice following anthrax toxin exposure. These data imply that PCP-I may be a potential vaccination adjuvant worthy of further investigation.