| Objective:To establish the experimental animal models of different rodent hosts and to observe the differences of rodent hosts susceptibility to Plasmodium berghei, and investigating the mechanism of rodent hosts susceptibility differences.Methods:(1) Kunming mice, BALB/c mice and SD rats were divided into normal control group and the infection group of 1, 3, 5, 7, 9 day, then ten animals of each experimental groups were injected with 1×106 P.b(1×107 P.b for rats).(2) Parasitemia, survival rate and the spleen wet weight of each group were recorded.(3) Flow cytometry were used to analyze the proportion of CD4+, CD8+, NK and NKT cells in peripheral blood of normal control group and infected groups.(4) ELISA method was used to detect the changes of Arginase, IFN-γ and IL-4 in peripheral blood of normal control group and infected groups.(5) The changes of NO and NOS in peripheral blood were detected by test kit of normal control group and infected groups.(6) Real time fluorescent quantitative PCR were used to detect the expression changes of peripheral blood PBMC TLR4 and TLR9 of normal control group and infected groups.Results:1. The parasitemia of Kunming mice and BALB / c mice gradually were increased after infection P.b, and finally wer all died. The parasitemia of SD rats were dected and the peak were occurred at day 5, and then the parasitemia gradually disappeared.The spleen weights of Kunming mice were significantly higher(P<0.01) than the normal group at day 1, 3, 5, 7, 9. When compared to normal group, for BALB/c group and SD rats group, statistical differences were found at day 3, 5, 7, 9(P<0.01 for BALB/c, P<0.05 for SD rats), except for day 1.2. After injection, the percentage of CD4+T lymphocytes in peripheral blood of Kunming mice was significantly increased(P<0.01) at day 1, 3, 5 when compared to the normal control group, and was decreased(P<0.05) at day 7, and had no statistical difference at dat 9. The percentage of CD8+T lymphocytes in peripheral blood of Kunming mice was decreased(P<0.05) at day 1, 3, 5 when compared to the normal control group, and was increased(P<0.05) at day 7, and had no statistical difference at day 9.For BALB/c mice group, after injection, the percentage of CD4+T lymphocytes in peripheral blood was signifycantly increased(P<0.05) at dat 1, 3 when compared to the normal control group,and was decreased(P<0.05) at day 7,and had no statistical difference at day 5, 9. The percentage of CD8+T lymphocytes in peripheral blood was increased(P<0.05) at day 1, 3,and was increased(P<0.05) at day 7,and had no statistical difference at dat 5, 9.For SD rats, the percentage of CD4+T lymphocytes in peripheral blood was increased(P<0.05) at day 1 when they compared to the normal control group, and had no statistical difference at day 3, 5, 7, 9. The percentage of CD8+T lymphocytes in peripheral blood was decreased(P<0.05) at day 1 when compared to the normal control group, and had no statistical difference at day 3, 5, 7, 9.3. After injection, the percentage of NK cell in peripheral blood of Kunming mice was increased(P<0.05) at day 1, 3, 5 when compared to the normal control group, had no statistical difference at day 7, and was decreased(P<0.05) at day 9. The percentage of NKT cell in peripheral blood of Kunming mice had no statistical difference at day 1, 5 when compared to the normal control group, and was increased(P<0.05) at day 3, and was decreased(P<0.01) at day 7, 9.The percentage of NK cell in peripheral blood of BALB/c mice had no statistical difference at day 1, 7 when compared to the normal control group, and was increased(P<0.05) at day 3, 5 and was decreased(P<0.05) at day 9. For NKT cells, in BALB/c mice group, there was no statistical difference at day 1 when compared to the normal control group, and was increased(P<0.05) at day 3, and was decreased(P<0.05) at day 5, 7, 9.After injection, the percentage of NK cell in peripheral blood of SD rat was increased(P<0.05) at day 1, 3, 5, 7 when compared to the normal control group, and had no statistical difference at day 9. The percentage of NK cell in peripheral blood of SD rat was increased(P<0.05) at day 1 when compared to the normal control group, and was significantly increased(P<0.01) at day 3, 5, 7, 9.4. After injection, the serum NO level of Kunming mice was increased(P<0.01) at day 1 day when compared to the normal control group, and had no statistical difference at day 3, 5, and was decreased(P<0.05) at day 7, 9. The serum NOS level of Kunming mice had no statistical difference at day 0, 1, 3, 5, 7, 9 when compared to the normal control group. The serum Arginase level of Kunming mice was decreased(P<0.05) at day 1, 3, and had no statistical difference at day 5, 7, 9.For BALB/c mice group, the serum NO level was increased(P<0.01) at day 1 when compared to the normal control group, and had no statistical difference at day 3, 5, and was decreased(P<0.05) at day 7, 9. The serum NOS level had no statistical difference at day 0, 1, 3, 5, 7, 9 when compared to the normal control group. The serum Arginase level was decreased(P<0.05) at day 1, 3, and was no statistical difference at day 5, 7, 9.For SD rats group, the serum NO level was significantly increased(P<0.01) at day 1, 3, 5, 7, 9 when compared to the normal control group. The serum NOS level had no statistical difference at day 0, 1, 3, 5, 7, 9. The serum Arginase level was decreased(P<0.05) at day 1, 3, 5, 7, 9.5. After injection, the serum IFN-γ level of Kunming mice group and BALB/c group were both increased(P<0.05) at day 1, 3, 5 when compared to the normal control group, and were both no statistical difference at day 7, 9. And the serum IL-4 level of Kunming mice group and BALB/c group were both was increased(P<0.05) at day 3, 5, 7, 9, but day 1.For SD rats group, the serum IFN-γ level was increased(P<0.05) at day 1, 3, 5,7 but day 9 when compared to the normal control group. The serum IL-4 level of SD rats group were increased(P<0.05) at day 5, 7, 9 compared to control group after injection of P.b, and was no statistical differences at day 1, 3.6. The TLR4 relative expression level of BALB/c mice in peripheral blood PBMC was significantly increased(P<0.01) at day 1, 3, 5, 7 when compared to the normal control group, and was decreased(P<0.05) at day 9. The TLR9 relative expression level of BALB/c mice in peripheral blood PBMC had no statistical difference at day 1, 3 when compared to the normal control group, was increased(P<0.05) at day 5, and was decreased(P<0.05) at day 7, 9.The TLR4 relative expression levels in peripheral blood PBMC were significantly increased(P<0.01) at day 1, 3, 5, 7 but 9, after injection of P.b, when compared to the normal control group. The TLR9 relative expression level of SD rats in peripheral blood PBMC were increased(P<0.05) at day 1, 3, 5, 7, 9 after injection of P.b when compared to the normal control group.Conclusion:(1) This experiment confirmed the phenomenon that in different rodent hosts had susceptibility differences, Kunming and BALB / c mice falled to control infection and died eventually, however SD rats had ability to effectively remove parasites and ultimate self-healing;(2) The huge level increasing of IFN-γ as well as the proportion increasing of CD4+T lymphocytes in the very early stage of infection, suggest that the Th1 like immune response played an important role in the process of anti-infection.(3) The NK and NKT cell ratio of Kunming and BALB / c mice increased firstly and then decreased, in contrast only the NK cells proportion of SD rats increased firstly and then decreased, the NKT cell proportion rose continusly, suggest that the NK and NKT cells played an important role in the clearance of Plasmodium parasites, which may be one of the reasons for the difference in their susceptibility.(4) The NO level of Kunming mice and BALB/c mice increased firstly and then decreased, while the NO level of SD rats rise continusly, suggest the NO plays a important role.(5) The TLR4 and TLR9 relative expression of BALB / c mice increased firstly and then decreased, however the TLR4 relative expression of SD rats increase and then gradually returne to normal, the TLR9 relative expression remain elevated, suggest that differences in relative expression of TLR9 may cause the susceptibility differences in the rodent hosts. |
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