# Immune-Enhancing Effect of Acanthopanax gracilistylus W. W. Smith Polysaccharides and Liposomes as Dilutions of Chicken Newcastle Disease Vaccine

## TL;DR

This study shows that polysaccharides from Acanthopanax gracilistylus and their liposomes boost chicken immune responses to vaccines, especially when used as adjuvants.

## Contribution

AGSPL liposomes are shown to be more effective than AGSP in enhancing vaccine immunogenicity in chickens.

## Key findings

- AGSP and AGSPL significantly increased chicken antibody levels and cytokine concentrations after vaccination.
- AGSPL outperformed AGSP in promoting immune cell proliferation and enhancing vaccine efficacy.
- AGSPL has potential as a natural, effective vaccine adjuvant or diluent for poultry.

## Abstract

This study aims to investigate the immunostimulatory effects of Acanthopanax gracilistylus W. W. Smith Polysaccharide and its liposomes on vaccine immunogenicity. Research has revealed that these two substances (particularly liposomes) effectively stimulate the proliferation of immune cells in chickens. Animal experiments demonstrated that following vaccination, they significantly elevate antibody levels and the content of multiple cytokines. This indicates that Acanthopanax gracilistylus W. W. Smith Polysaccharide and its liposomes can safely and effectively enhance vaccine immune responses, with liposomes exhibiting particularly pronounced effects. These findings provide crucial evidence for developing novel, highly effective adjuvants or diluents derived from natural plant sources. Future applications in poultry farming hold promise for enhancing vaccine efficacy and reducing disease incidence, carrying significant socioeconomic value.

Acanthopanax gracilistylus W. W. Smith is a traditional Chinese herbal medicine that contains a variety of bioactive components, including polysaccharides. In this study, a polysaccharide was extracted from A. gracilistylus (AGSP) using an aqueous alcohol precipitation method. The sugar and glucuronic acid contents of AGSP are 43% and 8.06%, respectively. It was consisted of seven monosaccharides, mannose (Man), rhamnose (Rha), glucuronic acid (GlcA), galacturonic acid (GalA), glucose (Glc), galactose (Gal), and arabinose (Ara), with molar ratios of 0.32:0.15:0.04:0.12:5.12:2.50:0.85. AGSP liposomes (AGSPL) was prepared via the reverse-phase evaporation method. The encapsulation rate of AGSPL was 45.17% and its average particle size, polymer dispersity index (PDI), and zeta potential were 98.79 nm, 0.191, and −8.38 mV, respectively. The proliferation of chicken splenic T and B lymphocytes was significantly promoted in vitro at AGSP concentrations of 125–250 μg/mL and AGSPL concentrations of 15.63–31.25 μg/mL and 1.95–15.63 μg/mL, respectively. In vivo, the HI antibody titers and the concentrations of IFN-γ, IL-2, IL-4, and IL-6 in the AGSP and AGSPL groups were higher than those in the vaccine control (VC) and blank control (BC) groups. The efficacy of AGSPL was superior to that of AGSP. These findings indicate that AGSP and AGSPL markedly enhance the immunogenicity of ND vaccines, especially AGSPL, which is a promising candidate for polysaccharide-based vaccine diluents or adjuvants.