HCMV截短UL83基因真核表达重组体的构建、转染及其免疫效力研究

为了构建人巨细胞病毒(HCMV)截短UL83基因真核表达重组体,实现其在Hep-2细胞中的稳定表达,研究该截短UL83基因真核表达重组体免疫效力,采用基因重组的方法,将HCMV AD169株截短UL83基因定向克隆到带有绿色荧光蛋白(GFP)作为报告基因的真核表达载体pEGFP-C1上,构建真核重组表达质粒pEGFP-C1-UL83;脂质体转染至Hep-2细胞中,G418筛选获得稳定表达pp65细胞表达系。经基因测序显示,重组体中截短UL83基因完全正确,RT-PCR和Western blot检测证实其可在Hep-2细胞中稳定表达。用该重组体和其表达产物在HCMV先天性感染小鼠模型上进行免疫保护试验显示,母鼠血清可检测到特异性抗HCMV pp65抗体,效价为:1∶2.51~1∶50.79;子鼠脑组织内未分离出病毒,亦未检测出病毒pp65蛋白抗原表达。初步结果表明,pEGFP-C1-UL83具有较好的免疫原性,可作为DNA疫苗刺激机体产生有效抗体,并具有阻止病毒垂直传播的保护性作用。

Construction and transfection of eucaryotic expression recombinant vector containing truncated region of UL83 gene of human cytomegalovirus and it's sheltered effect as DNA vaccine

To construct eucaryotic expression recombinant vector containing vivo truncated region of UL83 gene of human cytomegalovirus, realize its steady expression in Hep-2 cell, and study sheltered effect of the eucaryotic expression recombinant vector as DNA vaccine. A vivo truncated UL83 gene fragment encoding for truncated HCMV pp65 was obtained by PCR from human cytomegalovirus AD169 stock genome. By gene recombinant ways, the truncated UL83 gene fragment was cloned into eucaryotic expression vector pEGFP-C1 with reported gene coding GFP to construct recombinant vector pEGFP-C1-UL83. The recombinant vector pEGFP-C1-UL83 was tested by different methods including PCR, restriction digestion and gene sequencing. Test results showed the recombinant vector was constructed successfully. After pEGFP-C1-UL83 was transfected into Hep-2 cell by lipofectin mediation, expression of GFP and truncated pp65 fusion protein in Hep-2 cell was observed at different time points by fluorescence microscope. Results showed that quantity of fusion protein expression was the highest at 36h point. Then, Hep-2 cell was cultured selectively by RPMI-1640 containing G418 (200 microg/mL) to obtain a new cell stock of expressing truncated UL83 Gene fragment steadily. RT-PCR and Western blot results showed the truncated fragment of UL83 gene could be expressed steadily in Hep-2 cell. The result showed a new cell stock of expressing Tpp65 was established. This cell stock could be useful in some HCMV research fields, for example, it could be a tool in study of pp65 and HCMV infection, and it could provide a platform for the research into the therapy of HCMV infection. Immune sheltered effect of pEGFP-C1-UL83 as DNA vaccine was studied in vivo of HCMV congenital infection mouse model. The mouse model was immunized solely by pEGFP-C1-UL83, and was immunized jointly by pEGFP-C1-UL83 and its expression product. When the mouse was pregnant and brought to bed, differential antibody of anti-HCMV pp65 was tested by indirect ELISA in mother mouse, the infectious virus was separated with the method of virus separation, and pp65 antigen was checked up by indirect immunofluorescence staining in fetal mouse. Results showed differential antibody of anti-HCMV pp65 was produced in mouse model. Tilter of the antibody was from 1:2.51 to 1:50.79. Results of virus separation and pp65 checkup of fetal mouse brain tissue were negative. So the conclusion can be reached that pEGFP-C1-UL83 as DNA vaccine in vivo has sheltered effect which can prevent HCMV vertical transmission from mother mouse to her fetus.