CpG oligodeoxynucletide potently enhances cellular immune responses in suckling mice infected with human rotavirus / 中华传染病杂志

ABSTRACT

Objective To investigate the effects of CpG oligodeoxynucleotide (ODN) on cellular immune responses in suckling mice infected with human rotavirus (HRV). Methods Forty ICR suckling mice were randomly divided into four groups control group. HRV infection group, CpG ODN pretreatment group and CpG ODN treatment group. Suckling mice were sacrificed four days after rotavirus challenge. Small intestine and spleen samples were collected under sterile condition. Thedegree of small intestinal mucosal injures was evaluated with standard scoring criteria. The spleen index was calculated and spleen lymphocyte stimulation index was detected by methyl thiazolyl tetrazolium ( MTT) assays. Levels of gamma interferon (IFN-γ), interleukin-4 ( IL-4) in the supernatant of spleen lymphocyte culture were detected by enzyme linked immunosorbent assay (ELISA). T lymphocyte subsets were analyzed by flow cytometry. The data was compared by one way ANOVA. Results The scores of mucosal injures of mice in HRV infection group, CpG ODN pretreatment group and CpG ODN treatment group were 4. 00 ±1. 31, 2. 75 ±1. 28 and 2. 87 ±0. 99, respectively, and the differences among groups were statistically significant (F=ll. 32,P＜0. 01). The scores of mucosal injures in CpG ODN pretreatment group and CpG ODN treatment group were both lower than that in HRV infection group (P＜0. 05). Compared with control group, spleen lymphocyte stimulation index and the percentage of CD8+ T lymphocytes were higher, the percentage of CD4+ T lymphocyte and ratio of CD4+ /CD8+ T cells were lower, levels of T helper (Th)1 type cytokine IFN-y increased significantly in HRV infection group; while the spleen index, spleen lymphocyte stimulation index, percentages of CD4+ and CD8+ T lymphocytes, IFN-y levels were all increased in CpG ODN pretreatment group and CpG ODN treatment group (P＜0. 05). The spleen index, spleen lymphocyte stimulation index, the percentage of CD4+ T lymphocytes, CD4+/CD8+ ratios and IFN-y levels in CpG ODN pretreatment group and CpG ODN treatment group were all significantly higher than HRV infection group (P＜0. 05). Conclusion CpG ODN potently enhances cellular immune responses in ICR suckling mice infected with HRV and CpG ODN could induce dominant Th1 response.