长沙地区无偿献血人群隐匿性乙型肝炎病毒感染情况分析

Status of occult hepatitis B infection among free blood donors in Changsha

目的了解长沙地区无偿献血人群隐匿性乙型肝炎病毒感染(occult hepatitis B virus infection,OBI)流行情况,探讨HBV基因型分布特征和S区氨基酸突变的情况。方法对长沙地区检测结果为HBsAg-/HBV DNA+的无偿献血血液样本进行HBV血清标志物检测,对其中的OBI样本进行HBV病毒载量检测和S区基因扩增,分析血清学标志物抗HBs与病毒载量检出与否的关系,并对扩增产物进行HBV基因分型和突变位点分析。结果2019年1月—2020年1月长沙地区173893份无偿献血标本共确认58例OBI样本,OBI流行率为0.033%;共发现7种血清学模式,抗HBc单独阳性最多,占38.98%,所有样本中抗HBc阳性率为89.83%;16例样本能检测出病毒载量,其中14例样本浓度小于100 IU/ml;抗HBs阳性组和阴性组间的病毒载量检出率无统计学差异;75.0%(12/16)样本扩增出S区序列,基因型均为B型,均发生突变,其中11例的HBsAg抗原决定簇及周边主要亲水区域(major hydrophilic region,MHR)发生氨基酸突变。结论长沙地区无偿献血者中的OBI感染率在全国属于偏低水平;HBV基因型主要是B型,MHR区的氨基酸突变可能是造成OBI的原因,突变有本地特点。

Objective To investigate the prevalence of occult hepatitis B virus infection(OBI) among free blood donors in Changsha, and to explore the distribution characteristics of HBV genotypes and amino acid mutations in S region. Methods HBV serum markers were detected in free blood donation samples with HBsAg-/HBV DNA+ in Changsha. HBV viral load test and S-region gene amplification were performed on OBI samples. The relationship between anti HBs and viral load detection was analyzed, and the amplified products were analyzed for HBV genotyping and mutation sites. Results From January 2019 to January 2020, 58 OBI samples were confirmed from 173,893 free blood donors in Changsha, and the prevalence rate of OBI was 0.033%. A total of 7 serological patterns were found. The proportion of only anti-HBc positive was the highest, accounting for 38.98%. The positive rate of anti-HBc in all samples was 89.83%. Viral load was detected in 16 samples, of which 14 samples were less than 100 IU/ml. No statistically significant difference was found in the detection rate of virus load between the anti-HBs positive group and the anti-HBs negative group. 75.0%(12/16) of the samples amplified the S-region sequence, and the genotypes were all B type and mutated. Among them, 11 cases had amino acid mutations in HBsAg epitope and surrounding major hydrophilic region(MHR). Conclusion The OBI rate of free blood donors in Changsha is at a low level in China. The genotype of HBV is mainly type B. Amino acid mutation in MHR region may be the cause of OBI, and the mutation has local characteristics.