生物制品中猪细环病毒污染检测方法的建立和初步应用

Establishment and preliminary application of an assay for the detection of Torque teno sus virus ;strains

目的：建立生物制品中猪细环病毒（ Torque teno sus virus，TTSuV）污染的检测方法，并进行方法学分析及初步的应用。方法针对TTSuV保守序列设计引物和探针，建立荧光PCR方法，对方法的特异性、线性、精密度、最低检测限等参数进行验证，并对试验样本对检测的干扰性进行分析。利用该方法对猪全血样品、生产用细胞及轮状病毒疫苗样品进行检测，通过建立TTSuV分型检测的PCR方法对阳性样品进行分型。结果荧光PCR法的特异性较好，与不同种属的细小病毒、猴SV40病毒及猪圆环病毒无明显的交叉反应，TTSuV1和TTSuV2荧光PCR分别在109～103拷贝／μl和109～102拷贝／μl范围内线性较好，R2值达到0．993以上，TTSuV1和TTSuV2的最低检测限分别为1×103拷贝／μl和1×102拷贝／μl，试验内和试验间的Ct的精密度CV值均小于7％，试验内病毒拷贝数的CV值小于25％，试验间CV值小于45％。细胞样品成分对病毒检测无明显的干扰性。对20份猪全血样品进行检测，8份为阳性，其中1份为TTSuV1阳性，4份为TTSuV2阳性，3份为TTSuV1／2混合感染。 TTSuV1和TTSuV2型与标准株序列同源性分别为98％～99％和98％。对细胞样品和轮状病毒疫苗进行检测，结果均为阴性。结论成功建立了TTSuV荧光PCR检测法，能够用于生物制品TTSuV污染的检测，进一步提高了生物制品的安全性。

Objective To establish an assay for the detection of Torque teno sus virus （ TTSuV） strains and to analyze its preliminary application to biologics.Methods Primers and probe were designed according to the conserved sequences.A fluorescent PCR assay for the detection of TTSuV strains was estab-lished.Several parameters including the specificity, linearity, accuracy, sensitivity and anti-interference of the established assay were verified.The fluorescent PCR assay was performed to detect the samples of por-cine blood, cell substrate and rotavirus vaccine.The porcine blood samples positive for TTSuV strains were further genotyped.Results The established fluorescent PCR assay was confirmed to have high specificity as no cross-reactions with parvovirus virus of various species, SV40 and porcine circovirus strains were detec-ted.The linear range of the assay was 1×109-1×103 copies/μl for TTSuV1 genotype and 1×109-1×102 cop-ies/μl for TTSuV2 genotype with a R2 value more than 0.993.The sensitivity of the fluorescent PCR assay was 1×103 copies/μl for TTSuV1 genotype and 1×102 copies/μl for TTSuV2 genotype.The intra-and inter-CVs were both less than 7%in Ct values and less than 25% and 45% respectively in copies.No interfer-ence was found in the detection of TTSuV nucleic acids from cell samples.8 out of 20 porcine blood samples were positive for TTSuV strains, among which one sample was positive for TTSuV1 genotype, four samples were positive for TTSuV2 genotype and the rest were positive for both TTSuV1 and TTSuV2 genotypes.Com-pared with the reference strain, strains genotyped as TTSuV1 and TTSuV2 were respectively shared 98%-99%and 98%homologies in sequences.All of the cell substrate and rotavirus vaccine samples detected by the fluorescent PCR assay were negative for TTSuV strains.Conclusion The fluorescent PCR assay for the detection of TTSuV was established successfully, the application of which would further improve the safety of biologics.