| Objectives: The purposes of the present study are:①to confirm the therapeutic effects of allitridin against murine cytomegalovirus (MCMV) in disseminated infected mice;②to find out the dynamic changes on the transcription, expression and functions of IL-12 gene, a Th1/Th2 regulation factor, in systemic MCMV infected mice and the mechanism of murine cytomegalovirus escaping from cell-mediated immunity;③to investigate whether allitridin could interfere with the effects of MCMV infection on the transcription, expression and functions of IL-12 gene in order further to explore the mechanism of allitridin against CMV virus.Methods:MCMV Smith was prepared from salivary gland of MCMV infected mice. A systemically disseminated infected model was established in younger BALB/c mice without using immunosuppressant by means of inoculating MCMV Smith. The pathological changes in hearts, lungs, livers and kindeys of infected mice were examinated under the light microscope.The medium dosage of allitridin (25 mg/kg·d) in mouse was determined based on the medium dosage of drug (120 mg/d) in adult human. The experiments were grouped as the followings: allitridin treated group,placebo and blank controlls. The experimental mice were sacrificed at 3, 5, 7, 10, 14 days post-infection (p.i.), respectively, and thier spleen tissues were removed under the aseptic conditions.The infectious viral titer in salivary gland was quantified by plaque formation assay. The expressing levels of Th1/Th2 regulation factor IL-12 p70 and Th1 cytokine IFN-γin supernatant of spleen cell cultures were measured by double-antibody sandwich ELISA. The levels of IL-12 p35 and p40 mRNAs in spleen cells were analyzed by RT-PCR, respectively.Results: In systemic MCMV infected mice, histopathological damages were observed in their livers, kidneys, lungs and hearts; the expression of IL-12 p70 was up to the highest on day 3 p.i., and was persistently and significantly suppressed since day 5 p.i. (P<0.05). The level of IFN-γalso was the highest on day 3 p.i., then gradually decreased and returned to normal during the period of day 10 to 14 p.i.. The dynamic changes of IL-12 p35 gene transcription were completely same as those of IL-12 p70, while IL-12 p40 mRNA was in persistently and significantly higher level after infection (P<0.01).In allitridin treated model mice, the expression of both IL-12 p35 and p40 mRNAs and IL-12 p70 protiens significantly increased on day 3 p.i. with levels as almost same as that of placebo controls; then rapidly decreased and reverted to normal during the period of day 5 to 14 p.i., with obviously different levels compared with placebo controls. Moreover, allitridin could significantly and persistently up-regulate the expression of Th1 cytokine IFN-γwhich were much higher than those of both placebo and bland controls during the period of day 7 to14 p.i..Conclusions:A systemic MCMV infected BALB/c mice model was successfully established, which provided the effective researching systems for screening anti-CMV drugs and exploring the mechanism of CMV infections and CMV diseases.Significantly lower levels of IL-12 p70 and IL-12 p35 mRNAs since day 5 p.i. may be the one of major reasons of obviously lower expression of Th1 cytokines and inhibition of Th1 reactions during the later period of CMV infection. Persistent higher transcription of IL-12 p40 gene should lead to the significant rising of the antagonist, IL-12 (p40)2 which could further inhibit the functions of IL-12.Allitridin could completely correct the disturbance of expression of IL-12 gene caused by MCMV and persistently promote IFN-γexpression which were useful for enhancing the specific cellular immune reactions against CMV and clearance of CMV viruses from host, suggesting another mechanism of allitridin against CMV.
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