摘要目的 建立多房棘球蚴(泡球蚴)感染小鼠肝脏丝氨酸蛋白酶抑制基因(Serpina3g)实时荧光定量PCR(RT-qPCR)的检测方法及与常规RT-PCR检测方法的比较.方法 肉眼直视下肝脏穿刺注射100 μl泡球蚴组织匀浆液建立泡球蚴感染小鼠模型,3个月后将小鼠处死,Trizol法提取肝脏总RNA,反转录获得cDNA.依据Serpina3g的编码基因(NM_009251)保守序列,通过Primer 5软件设计定量引物,以β-actin作为内参.以健康小鼠肝脏获得的cDNA依次10倍梯度稀释制备标准品(1×10~2～1×10~6 pg),利用SYBR Green RT-qPCR方法检测Serpina3g基因,然后根据cDNA浓度与循环值(Ct)的线性关系,绘制标准曲线,确定RT-qPCR检测的最佳条件和重复性;并将RT-qPCR结果与常规RT-PCR琼脂糖凝胶电泳结果进行特异性、灵敏度和定量等方面的比较.结果 筛选出Serpina3g基因定量引物,最佳退火温度为56.4℃;RT-qPCR无非特异性扩增,标准品及样品熔解温度均在80.5℃,熔解峰单一;标准曲线斜率为-2.833(效率),相关系数r=0.996;5个不同梯度的样本(1×10~2-1×10~6pg)重复检测5次均为阳性,变异<5%;mRNA检出限为1×10~2 pg,总RNA在1×10~2～1×10~6 pg内均可以进行扩增;常规RT-PCR方法mRNA检出限仅为1×10~6 pg.结论 成功建立了小鼠源Serpina3g的PT-qPCR检测方法,在特异性、灵敏度、重复性和定量方面优于常规RT-PCR.

abstractsObjective To establish a real-time fluorescent quantitative PCR (RT-qPCR) for detection of Serpina3g of Echinococcus multilocularis infected mouse, and compare it with conventional RT-PCR. Methods To establish the mouse model, 100 μl homogenized metacestode was injected into the anterior liver lobe of the experimental mice. After 3 months, liver was sampled to extract the total RNA, and cDNA was obtained by reverse transcription. Primer was designed based on the nucleotide sequence of Serpina3g gene(NM_009251) by using soft of Primers 5. β-actin was used as a control, and the cDNA of mouse liver was constructed to detect the sensitivity and prepare the standard curve. The standard curve was prepared based on the linear relationship between the amount of cDNA and cycle threshold (Ct). The detection limit of conventional RT-PCR was determined by agarose gel electrophoresis and compared with RT-qPCR. Results For RT-qPCR, the designed primer was specific for detecting Serpina3g gene and the melt temperature was 80.5 ℃ for each sample and the standard curve. The melting curve analysis showed the same results. The slope of the standard curve was - 2.833 and the correlation coefficient r = 0.996. Five times of repeated determination showed positive results in 5 different samples(1×10~2～1×10~6pg). And CV was lower than 5%. Compared with a detection limit of 1×10~6 pg mRNA of conventional RT-PCR, the RT-qPCR assay had a detection limit of 1×10~2 pg mRNA with a dynamic range of detection from 1×10~2 - 1×10~6 pg mRNA. Conclusions The established RT-qPCR assay for detecting Serpina3g gene has high specificity and sensitivity with a noticeably low detection limit.