Fig. 5

The role of pcDNA3.1(+)-giardins in G. duodenalis infection. Mice were immunized (i.m.) with recombinant eukaryotic expression plasmids pcDNA3.1(+)-alpha-2 giardin or pcDNA3.1(+)-alpha-7.3 giardin and then challenged with G. duodenalis cysts (i.g.). The PBS group and pcDNA3.1(+) plasmid + G. duodenalis cyst treatment group were used as the negative control groups, whereas the G. duodenalis cyst single treatment group was regarded as the positive control group. a The experimental groups and treatment scheme. b The BW of mice in each different treatment group was monitored for 7 days after challenge. Asterisks indicate a significant difference between each group in the G. duodenalis group and pcDNA3.1(+)-alpha-2 giardin group at *P < 0.05, **P < 0.01 and ***P < 0.001; dollar signs ($) indicate a significant difference between each group in the G. duodenalis group and pcDNA3.1(+)-alpha-7.3 giardin group at ^$$P < 0.01 and ^$$$P < 0.001. c The parasite burden was determined by counting the trophozoites number in 1 ml of the duodenal lavage fluid from harvested duodenum (3 cm long) and presented as parasite number per centimeter duodenum. Differences among the G. duodenalis infection group, pcDNA3.1(+)-alpha-2 giardin group and pcDNA3.1(+)-alpha-7.3 giardin group were analyzed by one-way ANOVA using SPSS version 22.0 software. Asterisks indicate significant differences at **P < 0.01 and ***P < 0.001. d Histopathological changes in the duodenum. Red arrows point to villi lesions; green arrows point to crypt lesions. Scale bar: 100 μm. e, f Statistical analysis of villus height (e) and crypt height (f) in mice duodenum. Differences among each group within Fig. 1d were analyzed by one-way ANOVA using SPSS version 22.0 software. Asterisks indicate significant differences at *P < 0.05 and **P < 0.01. Results were obtained from seven independent biological experiments. n.s., Not significant (P > 0.05)