低病毒载量病毒在血浆标本中的分布规律及其检出概率的研究

Study on distribution regularity and detection probability of virus with low viral load in plasma specimens

目的探讨低病毒载量病毒在血浆标本中的分布规律及其检出概率，为采供血机构低病毒载量病毒血浆标本的检测提出合理方案。方法2018年1月，选择300份含量为2.5 IU/mL的乙型肝炎病毒（HBV） DNA标准品血浆标本，以及2017年3月山东省东营市中心血站留取的HBV＂窗口期＂感染者单人份血浆标本200 mL（平均分为40份），作为研究对象。采用实时荧光PCR法对所有研究对象的HBV DNA进行定量分析。采用拟合优度χ2检验，分析低病毒载量病毒在HBV DNA标准品血浆标本，以及HBV＂窗口期＂感染者血浆标本中的分布形式。并且通过不同稀释倍数的人类免疫缺陷病毒（HIV）-1 RNA和丙型肝炎病毒（HCV） RNA标准品血浆标本的阳性检出率，对低病毒载量病毒在血浆标本中的分布形式进行验证。结果①本研究300份含量为2.5 IU/mL的HBV DNA标准品血浆标本的HBV DNA检测结果显示，低病毒载量HBV在该血浆标本中的分布形式符合Poisson分布规律（χ^2＝0.779，P＝0.978）。②本研究40份HBV＂窗口期＂感染者血浆标本的HBV DNA检测结果亦显示，低病毒载量HBV在该血浆标本中的分布形式符合Poisson分布规律（χ^2＝0.446，P＝0.994）。③ HIV-1 RNA标准品被稀释成不同含量血浆标本时，随着稀释含量由166.67 IU/mL下降为1.00 IU/mL，HIV-1 RNA阳性检出率由100.0%下降为10.0%，但是总有阳性标本被检出。④ HCV RNA标准品被稀释成不同含量血浆标本时，随着稀释含量由33.33 IU/mL下降为0.50 IU/mL，HCV RNA阳性检出率由100.0%下降为28.3%，但是总有阳性标本被检出。结论病毒感染的患者体内，若病毒为低病毒载量时，该病毒可以被检出，但检出率不是100%，即存在正常的漏检现象。而增加检测次数可增加检出病毒的几率，有助于检出阳性标本。

ObjectiveTo study the distribution regularity and detection probability of the virus with low viral load, in order to propose a reasonable scheme for detection of the virus with low viral load in plasma specimens, and to make a scientific explanation for reasonable missing detection.MethodsIn January 2018, a total of 300 plasma specimens of hepatitis B virus （HBV） DNA standard with a content of 2.5 IU/mL, as well as 40 plasma specimens from 200 mL single plasma specimen of one HBV window period infected patient who taken from Dongying Blood Center in March 2017, were selected as research objects. All subjects were quantified for HBV DNA using real-time fluorescent PCR. The goodness-of-fit χ^2 test was used to analyze the distribution regularity of virus with low viral load in HBV DNA standard plasma specimens and HBV window period infected patient plasma specimens. Furthermore, the distribution regularity of virus with low viral load in plasma specimens was verified by the results of positive detection rates of human immunodeficiency virus （HIV）-1 RNA and hepatitis C virus （HCV） DNA standard plasma specimens at different dilutions.Results① In this study, the distribution of HBV DNA in 300 plasma specimens of HBV DNA standard with a content of 2.5 IU/mL was in line with the Poisson distribution （χ^2=0.779, P=0.978）. ② The distribution of HBV DNA in 40 plasma specimens of HBV window period infected patient was also in line with the Poisson distribution （χ^2=0.446, P=0.994）. ③ When the contents of HIV-1 RNA standard in plasma specimens were diluted from 166.67 IU/mL to 1.00 IU/mL, the positive rates of HIV-1 RNA reduced from 100.0% to 10.0%. But there was always a positive specimen could be detected out. ④ When the contents of HCV RNA standard in plasma specimens were diluted from 33.33 IU/mL to 0.50 IU/mL, the positive rates of HCV RNA reduced from 100.0% to 28.3%. But there was always a positive specimen could be detected out.ConclusionsIn one virus-infected patient whose viral load was low, its virus can be detected, but the detection rate is not 100%. There is a normal missed detection phenomenon. Increasing the number of tests could increase the chance of virus detection and help found out positive specimens.