Polysaccharides: Candidates of promising vaccine adjuvants

Abstract

Aluminium-based adjuvants remain the only adjuvants approved for human use in the USA for over 80 years because of alum's simplicity, tolerability, safety and cost-efficiency. Recent development of vaccines, especially the increasing applications of recombinant subunit and synthetic vaccines, makes aluminium adjuvants cannot stimulate enough immunity to the antigens, since aluminium adjuvants can only induce Th2 type immune responses. So, novel adjuvants are urgent to make up the disadvantages of aluminium adjuvants. However, some major hurdles need to be overcome, not only the scientific knowledge of adjuvants but also unacceptable side-effects and toxicity. A number of carbohydrate-based polysaccharides from plant, bacterial, yeast and synthetic sources can act as pathogen-associated molecular patterns (PAMPs) and recognize pattern recognition receptors (PRRs) on immune cells, followed by triggering innate immunity and regulating adaptive immunity. What is more, polysaccharides are safe and biodegradable without tissue deposits as observed in aluminium adjuvants. Therefore, polysaccharide-based compounds and formulations are potential vaccine adjuvant candidates. Here, we mainly review polysaccharide-based adjuvants investigated in recent years.

Natural Vaccine Adjuvants and Immunopotentiators Derived From Plants, Fungi, Marine Organisms, and Insects

“…21e25 Advax coadministered with vaccines induces Th1 (IgG2a, IL-2, IFN-g) and Th2 (IgG1, IgA, IL-5, IL-6) responses. 26 More details on inulin are given elsewhere in this book.…”

Marburg virus‐like particles produced in insect cells induce neutralizing antibodies in rhesus macaques

“…With advances in vaccine technology, natural polysaccharide adjuvants have emerged and have been used as immunopotentiators that improve antibody levels and promote cellular immunity . Research has demonstrated that adjuvant PCP‐II elicited antigen‐specific antibody levels in mice immunized with influenza vaccine and hepatitis B surface antigen (HBsAg).…”

N‐dihydrogalactochitosan as a potent immune activator for dendritic cells

“…Since the first reports of Coley's toxins (which were a mixed bacterial vaccine), a wide array of different immune activators have been tested for their ability to stimulate the immune system to combat cancer. The best known anticancer immune activators are probably BCG (used clinically for bladder cancer) and CpG oligodeoxynucleotide, but polysaccharides have also been tested . N ‐dihydrogalactochitosan (GC) is a new immune activator that was originally prepared by attaching galactose molecules to the amino groups of chitosan, a glucosamine polymer, in order to improve solubility in water at neutral pH, and to overcome problems of sterile filterability in the manufacturing process.…”