| Humans has been plagued by Influenza virus in human history, which causes seasonal flu every year, sometimes even global flu pandemic outbreak. Human direct infection with H5N1 avian influenza virus was first detected in Hong Kong in 1997. Since then, cases of human infection with multiple subtypes of avian influenza virus have been found. H7N9 influenza infected human was first found in shanghai of China in 2013.There had been 698 people infected in china and 281 people dead until January 2016. The fatality rate of 40.3% is about 60 times that of the A/H1N1 flu in 2009.Vaccination is the most effective way to prevent and control influenza virus so far. We usually adopt vaccine by the intramuscular route. However, this strategy can only provide a systemic immune response. Mucosal immunity can not only induce local mucosal immunity response, but also induce systemic immunity response. But the harsh natural environment of mucous membrane cavity could cause“alien” substance degraded or exclusion eliminated. Adding adjuvant can improve the effect of mucosal immunity response. There has no safe and effective mucosal immunity adjuvant been used in clinical so far. In this study, we used polygonatum polysaccharides(POP) as a mucosal immune adjuvant, analyzed and evaluated its efficacy in mouse model.Six to eight old BALB/c mice were used as an animal model and a single intranasal immunization was adopted. Firstly, we selected different doses(0.1μg, 0.33μg, 1μg and 3μg) of H7N9 influenza virus split vaccine for BALB/c mice intranasal immunization to explore the mucosal immunity effect of H7N9 influenza split vaccine. According to the result,We studied the mucosal immune adjuvant effect of H7N9 influenza virus spilt vaccine by adding different doses of polygonatum polysaccharides(400μg, 600μg, 800μg, 1000μg and 1200μg). We detected the mice serum IgG,Ig G1,IgG2 a, and S-IgA by ELISA and detected the HI antibody by HI assay to evaluate the mucosal immune adjuvant effect of the polygonatum polysaccharides. Three weeks after the immunization,mice were challenged with a lethal dose of homologous virus, the mouse body weight and survival rate was monitored continuously for 21 days. Three days after the challenge, lung lotion was collected for virus load testing. Protective effect of polygonatum polysaccharides and H7N9 influenza virus vaccine was evaluated by mucosal immune against lethal dose challenge of the homologous influenza virus.The result showed that an increase in adjuvant dosage was accompanied with an increase in antibody titer. And all kinds of antibody titer were significant higher in mouse groups immunized with both vaccine and adjuvant than that only immunized with vaccine, when the dose of polygonatum polysaccharides reach to 1000ug/mouse. But, whenthe dose of polygonatum polysaccharides reach to 1200 ug/mouse,the antibody titer was lower than 1000ug/mouse. It means the vaccine group added that dose of polygonatum polysaccharides can induce stronger local mucosal immunity and system immunity response. Besides, IgG1 titer was higher than IgG2 a,which means that polygonatum polysaccharides is a kind of TH-2 adjuvant. In terms of weight loss and survival rate, when the dose of polygonatum polysaccharide reached to1000 ug/mouse, its protection effect was the best. The survival rate of vaccine alone group was 0%, but the survival rate reached to 75% when adding that dose of polygonatum polysaccharides which showed good adjuvant effect.The result showed that the POP can enhance the efficacy of H7N9 split vaccine by improving the efficiency of mucosal immune response induction, which make it a promising mucosal adjuvant candidate for further research. |
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