Objective To investigate the significance of human cyomeg Movirus(HCMV)pp65 IgG antibody avidity index(AI)for the clinical diagnosis of HCMV primary infection through the experimental model of HCMV primaly infection in BALB/c mice.Methods 6～8 weeks,female,specific-pathogen-free BALB/c mice were divided into 5 groups.6 mice in each group. And he mice were injected with 2×106 PFU/m1,2×105 PFU/mi,2×104 PFU/ml,2×103 PFU/ml and 2×102 PFU/ml of HCMV intraperitoneally respectively. Another 6 mice were injected intraperitoneally with the maximum dose of HCMV kept at 56℃ for 30 min as inactivated virus group.And HF negative control group was established at same time. All the mice ere sacrificed to obtain brain and lung tissues for the following experiments after 1 montll.(1)Tissue samples obtained from mice were inoculated in human embryo fibroblasts(HF)monolayers after routine treatment for virus isolation.HCMV specific eytopathie effect(CPE) was observed bv inverted phase-contrast microscopy.HCMV UL83 DNA in the ultures as tested by PCR and pp65 antigen was detected by indirect immunofluorescence.(2)Extracted mRNA from tissue samples and HCMV pp67 mRNA were analyzed by reverse transcriptase PCR(RT-PcR).(3)Immunoglobulin M(IgM)antibody and immunoglobulin G(1gG)antibody avidity Was investigated for their usefulness in distinguishing primary genital HCMV infections rom nonprimary infections with ELISA kit using truncated pp65 protein.ResultsHCMV can be isolated in the tissues from the mice injected with 2×106 PFU/ml and 2×105 PFU/m1.RT- PCR and ELISA showed positive results in the same groups.The infective rates were 100%.The analysis of the low doses groups,inactivated group and HF negative ontrol group all showed negative results.Conclusions BALB/c mice can be infected with HCMV and appeared as primary infection after1 month.Determination of HCMV pp65 IgM and HCMV p065 IgG-AI by ELISA incorporated with virus isolation and RT-PCR are helpful for distinguishing primary infections from nonpfimary infections.The detection of HCMV p65 IgM and HCMV pp65 IgG-AI by ELISA utilizing recombinant protein pp5 as antigens can be used for preliminary screening.%目的 通过对人巨细胞病毒(human eytomegalovims,HCMV)原发感染BALB/c模型小鼠感染状态的实验研究,探索检测HCMV pp65 IgG亲和指数(avidity index,AI)在原发感染诊断中的意义和作用.方法 取6～8周龄SPF(Specific Pathogen Free)级BALB/c雌性小鼠30只,分为5组,每组6只,分别用2×105、2×105、2×104、2×103和2×102PFU/ml的5个剂量的病毒悬液腹腔注射小鼠,1.0 ml/只;另取浓度为2×106PFU/ml剂量的病毒,经56℃30 min灭活后,1.0 ml/只腹腔注射雌性小鼠共6只,作为灭活对照组;同株同代的HF细胞悬液1.0 ml/只腹腔注射雌性小鼠共6只,作为HF细胞对照组.各组小鼠于屏障系统内饲养1个月后,检测小鼠的感染状态.病毒分离检测脑、肺组织中感染性病毒颗粒,观察HCMV特异性细胞病变效应,PCR试验检测细胞培养物UL83基因,间接免疫荧光试验检测细胞玻片pp65抗原;逆转录-聚合酶链反应(RT-PCR)检测小鼠脑、肺组织中HCMV pp67的转录;同时,用本室自制的截短pp65抗原制备的ELISA试剂盒检测血清标本中HCMVpp65特异性IgM抗体和IgG-Al.结果 2×104PFU/ml和2×105PFU/ml剂量的病毒感染小鼠后,脑、肺组织中均可检测到感染性病毒颗粒,感染率均为100%;RT-PCR均可检测到小鼠脑、肺组织中pp67转录产物;血清学检测这两组小鼠HCMV pp65 IgM均为阳性,HCMV pp65 IgG-AI＜50%;检测结果判断该两组小鼠为HCMV原发感染.余低剂量病毒组、灭活病毒组和人胚成纤维细胞(HF)对照组检测结果均为阴性.结论 HCMV AD169株可感染BALB/c小鼠,初次感染病毒1个月后可表现原发感染状态;以HCMV pp65重组蛋白为抗原榆测特异性IgM抗体以及相应IsG-AI间接ELISA法,可作为对HCMV原发感染的初筛手段,是诊断HCMV原发感染有效的方法之一.
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