PCR法评价泼尼松龙诱导弓形虫隐性感染小鼠的复发及阿奇霉素对复发的疗效

目的探讨PCR方法诊断泼尼松龙诱导弓形虫隐性感染小鼠复发的敏感性及阿奇霉素对其复发的治疗效果。方法36只20g左右的雌性ICR小鼠以每组6只随机分成正常组（C）、泼尼松龙组（P）、感染弓形虫组（I）、感染弓形虫＋阿奇霉素组（IA）、感染弓形虫＋泼尼松龙组（IP）、感染弓形虫＋泼尼松龙组＋阿奇霉素组（IPA）。0周,I组、IA组、IP组和IPA组小鼠分别经腹腔注射感染Prugniaud株弓形虫包囊10个/只;第6～7周,P组、IP组、IPA组小鼠每只每天后肢内侧皮下注射盐酸泼尼松龙1mg,IA组、IPA组小鼠每只每天按250mg/kg剂量腹腔注射阿奇霉素。分别在0、1、2、3、4、5、6、7周对各组小鼠采血,并萃取全血DNA,通过PCR法扩增弓形虫特异性B1基因。第7周剖杀所有小鼠计数其脑组织弓形虫包囊数。结果相比AF14652基因引物,B1基因引物敏感度更高且特异性好;感染弓形虫前5周的小鼠可以通过PCR方法扩增到B1基因特异性产物,5周后PCR法未能扩增出特异性产物;感染弓形虫激素组（IA）小鼠在使用泼尼松龙2周后小鼠全部死亡,感染弓形虫激素治疗组（IP）小鼠死亡率低（P〈0.05）;相比感染组（I）和感染＋阿奇霉素组（IA）和感染＋泼尼松龙＋阿奇霉素组（IPA）,感染＋泼尼松龙组（IP）小鼠脑组织包囊个数显著增加（P〈0.01）。结论在PCR方法诊断中,B1基因是很好的诊断弓形虫病的目的基因;泼尼松龙能诱导弓形虫隐性感染小鼠的复发并导致小鼠的死亡;阿奇霉素对弓形虫病治疗有效,但不能完全治愈弓形虫病。

PCR-based evaluation of perdnisolone-induced relapse of asymptomatic Toxoplasma gondii infection and therapeutic efficacy of azithromycin

Objective To investigate the PCR-based evaluation of prednisolone-induced relapse of asymptomatic Toxoplasma gondii infection and the therapeutic efficacy of azithromycin.Methods A total of 36 of female ICR mice,about 20 g,were randomly divided into 6 groups:contrast group (C),prednisolone group (P),infection group(I),infection plus prednisolone group (IP),infection plus azithromycin group(IA),infection plus prednisolone and azithromycin group (IPA).The infection group (I),infection plus prednisolone group(IP),infection plus azithromycin group(IA),infection plus prednisolone and azithromycin group (IPA)were challenged at week 0 with 10 cysts of Toxoplasma gondii Prugniaud strain per injection intraperitoneally.The prcdnisolone group (P),infection plus prednisolone group (IP) infection plus prednisolone and azithromycin group (IPA)were injectied with prednisolone 1 mg into hind medial subcutaneous every day from the 6th week to 7th week.The infection plus azithromycin group(IA),infection plus prednisolone and azithromycin group (IPA) were injectied with azithromycin 250 mg/kg intraperitoneally every day from the 6th week to 7th week.The serum samples were collected and DNAs extracted at week 0,1,2,3,4,5,6 and 7 for amplification of Toxoplasma gondii of specific B1 gene by PCR.All the mice were sacrificed 7 weeks after the challenge to calculate the number of cysts in brain tissues.Results Compared with the primer of AF146527 gene,the primer of B1 gene was more sensitive and specific.The method of PCR could amplify the productions of specific B1 gene Toxoplasma gondii 5 weeks before the challenge,while it could not amplified 5 weeks after the challenge.All the mice of the IP group were dead 2 weeks after the injection of prednisolone (week 7),and the only two mice of the IPA group were dead at the same time (P <0.05),respectively.Compared with the I group,IA group and IPZ group,the number of cysts in brain tissues of the IP group significantly increased (P <0.01).Conclusions B1 as target gene is more suitable for diagnosis of Toxoplasma gondii infection by PCR.Prednisolone could induce the relapse of asymptomatic Toxoplasma gondii infection of mice and the mice are finally dead.Azithromycin is effective but it can not completely cure the Toxoplasma gondii infection.