Objective: To discuss the effect of polysaccharides from Tegillarca granosa as an adjuvant on pcDNA3.1-Sj26GST vaccine against Schistosoma japonicum infection.
Methods: Sixty SPF BALB/c mice were divided into four groups randomly (15 mice each group), including a control group, a polysaccharides group, a vaccine group, and a vaccine plus polysaccharides group. In the 0, 2th and 4th week of the experiment, the mice in the above four groups were immunized for 3 times with 100 μl PBS, 100 μg polysaccharides from Tegillarca granosa, 100 μg Sj26GST vaccine, and 100 μg Sj26GST vaccine plus equivalent polysaccharides, respectively. Two weeks after the last immunization, all the mice were infected with 40 ± 1 Schistosoma japonicum cercariae through the skin of the abdomen. After the infection for 6 weeks, all the mice were sacrificed, and their serums, livers and the adult worm of Schistosoma japonicum in them were collected, the specific sera IgG antibodies were detected by ELISA, and the worm reduction rates and egg reduction rates in the liver were calculated.
Results: Six weeks after the infection, the IgG antibody levels of the mice in the vaccine group and the vaccine plus polysaccharides group were 18.26 ± 0.42 mg/ml and 20.21 ± 0.89 mg/ml respectively, the difference between them were statistically significant, and both of the IgG levels of the above groups were significantly higher than those in the control (both P < 0.05). The worm reduction rate and egg reduction rate in the vaccine group were 28.60% and 35.84%, respectively, and the rates in the vaccine plus polysaccharides group were 38.04% and 49.74%, respectively, the differences between the worm reduction rates and egg reduction rates were both statistically significant (both P < 0.05). Meanwhile, the two rates in the two above groups were all significantly higher than those in the control group (all P < 0.01).
Conclusion: Polysaccharides from Tegillarca granosa using as an adjuvant can increase the protection effect of pcDNA3.1-Sj26GST vaccine against Schistosoma japonicum infection.