隐匿性感染的慢性乙型肝炎患者HBV S基因分析

Analysis of hepatitis B virus S gene in occult infection among patients with chronic hepatitis B

目的 研究慢性乙型肝炎(CHB)患者中隐匿性乙肝病毒(HBV)感染的特点,分析S基因突变及发生隐匿性感染的可能原因.方法 收集CHB患者经治疗后血清学HBsAg检测结果转为阴性而HBV DNA阳性的标本10例.采用实时定量PCR进行HBV DNA定量检测.PCR扩增HBV S区基因,并进行克隆测序.结果 10例标本ALT均正常(23.3±13.3U/L),定量和定性试剂检测血清学HBsAg结果均为阴性,HBV DNA定量结果均为阳性且病毒载量相对偏低(中位数:4.82×104拷贝/ml).经S基因测序分析,10例标本均存在S区基因突变,其中8例标本存在不同突变株或突变株与野生型的混合感染,突变频率较高的位点为T47A、L98V、I/T126N/S、T131N、M133T/I、W172*、M198I、W199*、N207T.结论 CHB患者经过抗病毒治疗后HBsAg转为阴性的病例中存在隐匿性HBV感染,发生隐匿性感染可能与HBV S基因突变或循环HBsAg低于检测限有关,使用敏感度高的试剂进行HBV DNA检测有利于CHB患者治疗后隐匿性HBV感染的发现.

Objective To further explore the occult hepatitis B virus(HBV) infection in patients with chronic hepatitis B(CHB) and analyze S gene mutations and the possible reasons of occult infection.Methods Sera of 10 CHB patients carrying HBsAg negative with HBV DNA positive after treatment were collected.Real-time polymerase chain reaction(PCR) was used.S gene amplification products were obtained by PCR,and clonal sequencing were then used for these samples.Results For 10 samples,ALT results were normal(23.3 ± 13.3U/L),serological HBsAg results were negative by qualitative and quantitative reagents.HBV DNA quantitative results of 10 samples were positive and low (mean:4.82 × 104 copies/ ml).Sequencing disclosed S gene mutations in all 10 samples.Among them,co-existences of the different mutants or mutants with wild-type were found in 8 samples.The mutation points with high frequency included T47A、L98V、I/T126N/S、T131N、M133T/I、W172 * 、M198I、W199 * 、N207T.Conclusions Occult HBV infection existed in CHB patients after treatment.Factors contributing to the occult HBV infection include S gene mutations and low levels of circulating antigen which are below the assay limit of detection.The use of highly sensitive reagents for HBV DNA detection is beneficial to the detection of occultHBV infection in CHB patients after treatment.