Analysis of HBV infection after blood transfusion in Japan through investigation of a comprehensive donor specimen repository

BACKGROUND: To understand the risk of transfusion-transmitted viral infection, it is important to precisely assess cases of infection that follow transfusion. STUDY DESIGN AND METHODS: HBV infections noted after transfusion in 1997, 1998, and 1999 were analyzed. Transfusion in all these cases was performed before NAT was adopted for donor screening. To detect viral infection, PCR and serologic tests for HBV were performed retrospectively on all blood samples from implicated donors that had been stored in a frozen state after each donation. The concentration of HBV genome was measured in HBV-positive blood samples. RESULTS: One hundred three cases of HBV infection were analyzed; of these, only 16, including at least 10 infections due to window-period (HBsAg-positive by reverse particle hemagglutination assay) donations, were confirmed by further testing to be related to transfusion. The concentrations of HBV genome were very low in four blood samples (<50, 400, 500, and 800 genome equivalents/mL of plasma). CONCLUSIONS: The remaining risk of transfusion transmission of HBV infection before the adoption of NAT was mainly due to window-period donations, including one that was made before the HBV genome was detectable by PCR. However, it was determined that transfusion was not responsible in many cases for HBV infection after transfusion.     

Evaluation of automated RNA-extraction technology and a qualitative HCV assay for sensitivity and detection of HCV RNA in pool-screening systems

BACKGROUND: The objective of this study was the evaluation of NAT technology for the detection of HCV RNA in plasma pools according to the recommendations of the Paul Ehrlich Institute (5000 IU/mL/donation) and the Committee for Proprietary Medical Products (100 IU/mL/manufacturing pool). STUDY DESIGN AND METHODS: Serial dilutions of both the EUROHEP standard (3,800 genome equivalents [geq]/mL; HCV genotype 1) and the World Health Organization (WHO) international standard (100,000 IU/mL; HCV genotype 1) were made in S/D plasma (ESPEP plasma, OctaPharma), which was nonreactive in serologic tests. Serial dilutions of plasma (2 mL) were used for extraction of HCV RNA with an automated version of a nucleic acid isolation method (NucliSens Extractor, Organon Teknika). HCV RNA was co-extracted from 2 mL of plasma, together with 84 copies of an in vitro-synthesized single-strand RNA serving as internal extraction control (IC) to monitor the efficiency of extraction and PCR. Amplification and detection of both HCV RNA and IC RNA were performed with an automated PCR system and a qualitative HCV assay (COBAS Amplicor 2.0 HCV, Roche Diagnostics). RESULTS: A cutoff value of 16 geq per mL (10/10 runs [100% hit rate]) was found by using the EUROHEP standard, whereas the WHO international standard had a cutoff value of approximately 12 IU per mL (10/10 runs [100% hit rate]). The IC had a cutoff value of approximately 17.5 copies per mL (6/6 runs [100% hit rate]). Forty-two copies per mL of IC RNA were found in 282 of 284 runs (99% hit rate). The negative controls (ESDEP plasma) were negative in all experiments. Experiments with pool sizes of 12, 24, 48, and 96 using serial dilutions of the WHO international standard revealed a cutoff value of 8 IU per mL (100% hit rate). The EUROHEP standard and the WHO international standard were detected with a 50 percent detection endpoint of 5.2 geq per mL and 1.5 IU per mL, respectively. CONCLUSION: This test system (NucliSens Extractor, and the COBAS Amplicor 2.0 HCV assay) revealed a high sensitivity for HCV RNA; considering the proposed requirements for sensitivity of NAT assays for the detection of HCV RNA in donor plasma, pool sizes of about 400 donors are possible. These endpoint results indicated that 1 IU is equal to about 3.4 geq.     

Comparison of the sensitivity of NAT using pooled donor samples for HBV and that of a serologic HBsAg assay

BACKGROUND: Studies were conducted using samples from early and late-stage HBV-infected persons to determine the pool size at which PCR had better sensitivity than a sensitive HBsAg chemoluminescence immunoassay (CLIA-HBsAg). STUDY DESIGN AND METHODS: HBV seroconversion panels were tested for HBsAg by CLIA and for HBV DNA by nested PCR (95% hit rate: 100 copies/mL); PCR was carried out at various dilutions. HBV serologically positive samples that were detected from the simultaneous screening of 540,161 routine whole-blood donations using CLIA-HBsAg and agglutination assays were also characterized for additional markers of HBV infection. RESULTS: In 9 of 10 HBV seroconversion panels, PCR had better sensitivity than CLIA-HBsAg at dilutions of 1-in-25 or lower. Of 65 CLIA-only confirmed-positive donor samples (agglutination assay-negative), 8 represented early infection, 2 of which were PCR positive at a 1-in-50 dilution but negative at a 1-in-100 dilution. Only 2 of 47 samples from probable late-stage HBV infection that were positive on CLIA only were PCR positive with 0.1-mL sample volume and the S-region primer; the remaining 45 samples required a 1.0-mL sample input and C-region primer for increased PCR positivity. The remaining 10 CLIA-only confirmed-positive donor samples were from HBV vaccine recipients. None of the 12 CLIA- and HBsAg-negative donor samples that were strongly anti-HBc reactive could be detected by PCR at any dilution; all 12 were PCR positive when undiluted, but 4 required a 1.0-mL input volume for PCR positivity. CONCLUSION: For the detection of samples representing early-stage HBV infection, PCR at dilutions of 1-in-25 or lower (equivalent to a pool of < or =25 members) had greater sensitivity than CLIA-HBsAg. In contrast, samples from late-stage HBV infection were detected by PCR only with undiluted samples (0.1-mL or 1.0-mL input volumes), regardless of CLIA-HBsAg reactivity. Therefore, although NAT using minipools of 25 donations or less may be effective for the detection of early-stage HBV infection, it may not be effective for the detection of persistent HBV infection.     

Routine HCV PCR screening of blood donations to identify early HCV infection in blood donors lacking antibodies to HCV

BACKGROUND: Detection of early hepatitis C infection of blood donors is still a major problem for blood transfusion. Common anti-HCV screening assays show differences in sensitivity and specificity. The often mild symptoms of acute hepatitis C also cause difficulties in the identification of early HCV infection. The feasibility and efficacy of routine screening of blood donations for HCV RNA were investigated. STUDY DESIGN AND METHODS: Blood donations (n = 251,737) were screened for HCV RNA over 4 years. RNA extraction, amplification, and detection were done by two commercial HCV PCR kits (HCV Cobas Amplicor and HCV Cobas Amplicor 2.0, Roche Diagnostics). Screening was done by pool testing with a maximum pool size of 40 serum samples. RESULTS: Three donations out of 251,737 were HCV RNA positive and anti-HCV negative. ALT levels of these donations were 271, 32, and 10 U per L. The HCV infection of a fourth HCV RNA-positive donor could not be identified by routine, second-generation HCV EIA (Abbott Diagnostika). In this case, two previous donations were also HCV RNA positive, and three second-generation test systems (Abbott) could not detect anti-HCV, whereas third-generation anti-HCV screening assays detected antibody with different sensitivity. The first HCV RNA-positive donation was identified only by the HCV ELISA 3.0 (Ortho Diagnostic Systems). The results of confirmatory assays like RIBA HCV 3.0 (Ortho) and Matrix (Abbott) indicate a restricted immune response to NS3 only. CONCLUSION: HCV RNA detection by PCR can be carried out routinely in blood donor screening without significant delay of release of the components. The residual risk of transmission can be reduced by identification of early infection, which can lead to an improved safety of blood components. RNA screening can also be advantageous in cases of incomplete or lack of antibody response to HCV.     

Prevalence of the newly described human circovirus, TTV, in United States blood donors

BACKGROUND: A novel nonenveloped single-stranded circular DNA virus (TTV) was recently identified. The prevalence of TTV in blood donors in the United States is, however, still unclear. STUDY DESIGN AND METHODS: Viral DNA was detected in US blood donors from five cities by using two sets of TTV primers: NG059/NG061/NG063 primers, which amplified the conserved region of strains 1 and 2, and T801/T935 primers, which amplified the 5' end region of the TTV sequence. A TTV antibody assay system was based on the detection of the truncated open reading frame (ORF)-1 (amino acids 1-411) from type 1b. The truncated ORF-1 was expressed as a fusion protein in Escherichia coli, and the fusion protein was used as the antigen in the antibody assay system. RESULTS: Viremia was detected in 21 (8. 4%) of 250 donors by use of NG059/NG061/NG063 primers and 104 (41. 6%) of 250 by use of T801/T935 primers. There was little correlation among the assays, which suggests the preferential detection of different strains with the different primers. TTV antibody was detected in 38 of 100 donors: 32 (84%) of 38 with concurrent TTV viremia and 6 (16%) of 38 without TTV viremia. TTV viremia and/or TTV antibody-positive samples were detected in 52 (52%) of 100 of US blood donors. CONCLUSION: Evidence of infection or exposure to TTV appears to be common among blood donors in United States.     

Value of anti-HBc screening of blood donors for prevention of HBV infection: results of a 3-year prospective study in Northwestern Greece

BACKGROUND: The risk of infection with transfusion-transmitted viruses has been reduced remarkably. However, a zero-risk blood supply remains a popular goal. Some authorities have introduced the screening for antibody to HBc (anti-HBc) as a surrogate test for the presence of several infectious agents. A 3-year prospective study was conducted in the Epirus region of Greece to determine the prevalence of several blood-borne viruses. One component of the study was the prevalence of HBV infection markers and the potential value of anti-HBc testing of donors in this area. STUDY DESIGN AND METHODS: Between January 1, 1995, and December 31, 1997, some 6696 donors were investigated for the presence of HBV infection markers by standard EIAS: Every sample that tested HBsAg-negative but anti-HBc-reactive alone or in combination with either or both antibodies to HBV e antigen (anti-HBe) and low-titered antibodies to HBsAg (anti-HBs <20 mIU/mL) was further investigated for the presence of HBV DNA by a combination of PCR and DNA EIA. RESULTS: Of these 6696 donors, 15.8 percent tested positive for at least one serologic marker of HBV infection (HBsAg prevalence, 0.85%). Anti-HBc reactivity alone or in combination with either or both anti-HBe and low-titered anti-HBs was found in 282 donors (4.2%). None tested HBV-DNA positive. No transfusion-associated HBV infections were recorded in the recipients of the above 282 blood units. CONCLUSION: A moderate prevalence of HBV infection markers was found. However, taking into account previous studies from this region, it appears that the HBsAg prevalence has declined. In addition, the present study cannot recommend the introduction of anti-HBc screening as a surrogate marker of occult HBV infection. The adoption of this exclusion criterion in this region would result in unacceptably high rejection rates among otherwise healthy donors. The absence of any case of transfusion-associated HBV infection after the transfusion of all HBsAg-negative, anti-HBc-positive units appears to provide further support for the negative HBV DNA results. Before a consideration of screening donors, efforts must be focused on reducing the number of false-positive anti-HBc results.     

High-titer screening PCR: a successful strategy for reducing the parvovirus B19 load in plasma pools for fractionation

BACKGROUND: Human parvovirus B19 (B19) is regarded as a potential risk factor for certain patient populations receiving plasma components. STUDY DESIGN AND METHODS: The prevalence of B19 was determined in a limited plasma donor population. Conditions for high-titer screening PCR were designed to allow the removal of plasma donations in the acute phase of infection with virus loads >or=10(7) genome equivalents per milliliter before manufacturing. Antithrombin III lots originating from screened plasma were compared to lots originating from untested plasma with respect to their B19 DNA load by a sensitive PCR assay. RESULTS: B19 was shown to have a prevalence of about 1 per 800 plasma donations. Only a minority (1/8000) of occurrences were in the acute phase of infection. Removing plasma units with high virus load as determined by high-titer screening PCR significantly decreased peak virus loads of plasma pools for fractionation. Together with a virus-removal capacity of 10.4 log(10) of the manufacturing process, this screening resulted in a final antithrombin III product that was nonreactive for B19 on PCR. CONCLUSION: Combining the strategy of high-titer screening PCR with the virus reduction capacity of the manufacturing process considerably increased the margin of B19 virus safety of antithrombin III. This strategy should have positive impact on other plasma components as well.     

Quantitative and genotypic analysis of TT virus infection in Chinese blood donors

BACKGROUND: The TT virus (TTV) is a member of a newly described family of human viruses related to the C ircoviridae viruses. Its association with specific diseases has not been established, and screening of blood donors has not been implemented. To date, 16 genotypes have been identified. STUDY DESIGN AND METHODS: Sera from 471 healthy blood donors (aged 11-58 years) were randomly selected and tested for TTV by the use of two sets of primers: NG59d/NG61d/NG63d primers and T801/T935 primers. Quantitative competitive PCR (QC-PCR) was developed to measure the TTV DNA concentration among the blood donors. Sequencing of a part of the genome was performed to identify the various genotypes. Several samples showed a mixed genotype infection. RESULTS: TTV was detected in 251 (53.3%) of 471 healthy Hong Kong blood donors by the use of NG59d/NG61d/NG63d primers. The prevalence of the virus increased steadily with age (p = 0.03). TTV DNA was detected in 90 percent (90 of a randomly selected 100) of samples by the use of T801/T935 primers. TTV DNA concentration was also measured by QC-PCR in the blood donors who were positive for TTV DNA in the first round of the heminested PCR. TTV titers ranged from 4.8 x 10(2) copies per mL to 6 x 10(4) copies per mL, with a median value of 1.2 x 10(4) copies per mL. Sequencing and phylogenetic analysis of a 223-bp fragment from open reading frame 1 showed three main genotypes (G1 [60.7%], G2 [24.3%], and G3 [14%]) and a new genotype 17 (G17), with the latter bearing 60-percent nucleotide homology with other genotypes deposited at GenBank. In addition, a new TTV subtype, G2f, was found. CONCLUSION: The prevalence of TTV is high in healthy Chinese blood donors. Three main genotypes (G1, G2, and G3) were detected. In addition, a new TTV genotype, tentatively designated as G17, and a new subtype, G2f, were identified.     

TT virus infections among blood donors in Iceland: prevalence, genotypes, and lack of relationship to serum ALT levels

BACKGROUND: The TT virus (TTV) is a newly identified blood-borne virus. Its association with disease is still unknown, and screening of blood donors has not been implemented. Several genotypes of the TTV have been identified. STUDY DESIGN AND METHODS: Three hundred seventy healthy blood donors were randomly selected and tested for TTV by the PCR method. Sequencing of a part of the genome was performed to identify various genotypes of the virus. ALT levels were determined in both infected and uninfected individuals. RESULTS: The TT virus (TTV), was detected in the sera of 23 (6.2%) of 370 healthy Icelandic blood donors; this prevalence is lower than that reported in Japan but higher than that in Scotland. The virus was found in all groups over the age of 19. Sequencing and phylogenetic analysis of 202 bp from open reading frame 1 demonstrated genotypes 1b and 2b 2c and genotype 4 isolates, with the latter bearing 89-percent nucleotide homology with other genotype 4 sequences deposited at GenBank. One sample showed a mixed genotype 1b/2c infection. Serum ALT levels were within normal limits in all infected individuals. CONCLUSION: The TTV carrier state does not cause significant liver injury.     

Multicenter evaluation of PCR methods for detecting CMV DNA in blood donors

BACKGROUND: CMV DNA screening may be a useful adjunct to serologic tests in distinguishing potentially infectious blood donations from those that are "CMV-safe." However, there is currently no consensus on the optimal assay method for accurate detection of CMV DNA in donors. STUDY DESIGN AND METHODS: A blinded multicenter evaluation of seven CMV PCR assays was performed by five laboratories by using coded sets of analytical controls and donor blood samples. RESULTS: Five assays displayed sufficient sensitivity for donor screening, as judged by consistent detection of a minimum of 25 CMV genome equivalents (geq) in analytical controls constructed to contain from 1 to 100 CMV geq in background DNA from 250,000 cells, while the other two assays displayed inadequate sensitivity. Three sensitive assays, two based on nested PCR directed at the UL93 and UL32 regions of the CMV genome and another test (Monitor Assay, Roche), did not detect CMV DNA in samples from any of 20 pedigreed CMV-seronegative, Western blot-negative (S-/WB-) donors. Two other assays based on nested PCR occasionally detected CMV DNA in S-WB- samples, and one sensitive nested PCR assay directed at UL123 detected CMV DNA in a large proportion (85%) of S-WB- samples. CONCLUSION: Seven CMV PCR assays currently used for research and/or diagnostic applications displayed marked variations in sensitivity, specificity, and reproducibility when applied to coded analytical and clinical control samples containing cellular DNA from the equivalent of 250,000 WBCs. These results will be useful in the selection of assays with performance characteristics appropriate to donor screening objectives. They may also help explain discrepant findings from previous studies that used PCR to determine CMV DNA prevalence in seronegative and seropositive blood donors.     

Evaluation of a new PCR assay with competitive internal control sequence for blood donor screening

BACKGROUND: High-throughput nucleic acid testing for transfusion-relevant viruses by PCR requires contamination-proof methods with high sensitivity and validity. A new PCR reagent kit (TaqMan, PE BioSystems) reduces the risk of carry-over contamination by eliminating post-PCR processing. STUDY DESIGN AND METHODS: Oligonucleotide design was done with software specialized for designing the assays' (TaqMan) primers and probes. A template-derived competitive internal control sequence designed through site-directed mutagenesis was used to reveal failures in amplification. Assay sensitivity was determined for single-donor and single-patient testing and by spiking sample mini-pools. Three seroconversion panels were tested. RESULTS: Sensitivity is high, reaching 300 HBV genomes per mL of single-patient material on direct testing. A detection limit of 1000 HBV genome equivalents per mL of donor plasma is achieved for 96 pooled samples. The window period for HBV infection was reduced by 17, 10, and 63 days from that for HBsAg screening in three seroconverting donors. CONCLUSION: The assay provides sufficient sensitivity to be superior to HBsAg screening in transfusion medicine and will be useful in clinical laboratories because of its ease of handling.     

Knowledge of HIV/AIDS transmission and screening in United States blood donors

BACKGROUND: Increased knowledge of HIV transmission and behavioral and test screening may encourage high-risk blood donors to self-defer. STUDY DESIGN AND METHODS: Knowledge of HIV transmission and screening and the association with demographics, screening test reactivity, and unreported deferrable risks (UDRs) was assessed by a 1998 anonymous mail survey sent to 92,581 blood donors, of whom 57 percent responded. Groups were compared by using weighted chi-square tests and logistic regression analysis. RESULTS: Four percent of the donors thought that it was very likely or somewhat likely for a person to contract HIV from donating blood, and 20 percent perceived a similar risk from blood transfusion. Only 60 percent of the donors knew that the available screening tests may not detect a recent infection. Thirty-seven percent either did not know or felt it was acceptable to donate blood to obtain HIV testing. Those most likely to answer knowledge questions incorrectly were more likely to have a higher prevalence of test reactivity or UDRs and to be 相似文献   

Two HBV DNA+/HBsAg− blood donors identified by HBV NAT in Shenzhen, China

Background

In order to further improve blood safety, mini-pool (MP) nucleic acid testing (NAT) was implemented to screen samples negative for hepatitis B surface antigen (HBsAg), anti-hepatitis C virus (anti-HCV), anti-human immunodeficiency virus (anti-HIV), syphilis (anti-Treponemal antibody) and with normal ALT.

Study design and methods

From August 2006 to February 2008, 41,301 donations were screened using commercial HIV/HCV RNA and HBV DNA Real-Time PCR NAT assays in pools of 8. Reactive pools were re-tested as individual samples using the appropriate screening test and confirmed using an alternate commercial NAT assay. Donors reactive on both NAT assays were considered ‘confirmed’ positive for the virus concerned and recalled for additional follow-up testing and counseling.

Results

Of the 41,301 samples screened, no HIV or HCV RNA-positive/seronegative donations were detected but two HBV DNA positive/HBsAg negative blood donors (Donors 1 and 2) were identified. Their respective hepatitis immunological markers were: Donor 1 - anti-HBc positive/anti-HBe positive/HBeAg negative/ALT normal and HBV DNA viral load of 112 IU/ml; Donor 2 - anti-HBc positive/anti-HBe negative/HBeAg negative/ALT normal and HBV DNA viral load 2750 IU/ml.

Conclusions

MP NAT identified two HBsAg negative donors with presumed occult infection but no HIV or HCV seronegative/NAT positive (yield) donors. The HBV yield rate of 1 in 20,650 (95%CI - 1 in 5663 to 1 in 75,303) is comparatively high, exceeds the predicted rate based on previous modeling for the population and demonstrates the incremental blood safety value of NAT in countries where HBV is highly epidemic. The low viral load of the two yield samples underscores the importance of optimizing the sensitivity of the HBV NAT assay selected for screening.     

Systematic survey of monoclonal gammapathies in the sera from blood donors

Routine screening of monoclonal gammapathies (M.G.) was performed on the serum of 13,914 blood donors by cellulose acetate electrophoresis. Twenty-six cases of M.G. were detected corresponding to a frequency of 0.19 per cent. The incidence of the M.G. progresses with increasing age comparatively to the age distribution of the blood donors under investigation. Most of the M.G. detected can be classified as "asymptomatic" M.G. (23 of the 26) and heavy chain classes are only IgG or IgM with a large predominance of IgG class (about 90%). It is suggested that donors in whom M.G. have been detected should not be eligible for blood donation. A yearly clinical, hematologic and immunoglobulin checkup is recommended for these patients in order to detect a possible malignant transformation.     

上海地区无偿献血者乙肝病毒核酸检测分析

目的了解无偿献血者乙肝病毒核酸筛查(NAT)阳性人群特点,为血液安全策略提供参考。方法无偿献血者血液经Murex和科华HBsAg ELISA试剂检测,结果为阴性的血液使用cobas TaqScreen MPX试剂进行HBV DNA,HCV RNA,HIV RNA 3项联合核酸检测。对于MPX反应性标本,使用COBAS AmpliPrep/TaqMan进行核酸鉴别试验,同时使用罗氏ECL电化学发光检测系统进行乙肝补充血清学试验。结果 2011年11月1日～2012年1月31日3个月共有献血者86 375人(次),其中有63 351人(次)为初次献血者,HBsAg反应性为1.04%,23 024人(次)为重复献血者,HBsAg反应性为0.46%,两者差异有统计学意义(χ2=63.63,P0.05)。84 990份HBsAg、抗-HCV、抗-HIV1/2阴性血液进行MPX核酸检测,共发现52例(0.060%)HBV DNA阳性,均为低拷贝,含量为(20～200)IU/ml间,其中32例(0.051%)来自初次献血者,20例(0.087%)来自重复献血者,两者比例差异无统计学意义(χ2=3.65,P0.05),没有发现HCV RNA与HIV RNA阳性。结论重复献血者HBsAg反应性比率低于初次献血者;HBsAg阴性献血者HBV DNA阳性率为0.060%,重复献血者HBV DNA阳性率与初次献血者比较,两者差异无统计学意义;开展HBV核酸检测能够进一步保障血液安全。     

Seroindeterminate patterns and seroconversions to human T-lymphotropic virus type I positivity in blood donors from Martinique, French West Indies

BACKGROUND: Screening for human T-lymphotropic virus type I (HTLV-I) antibodies in volunteer blood donors has been systematic in the French West Indies since 1989. Western blot-indeterminate results are commonly obtained. The significance of these indeterminate serologic patterns in HTLV-I-endemic areas is still unclear. STUDY DESIGN AND METHODS: During a 2-year period, 9759 blood donors were tested for HTLV-I antibodies. The epidemiologic features of HTLV-I-seropositive, -seroindeterminate, and -seronegative donors were compared. A lookback investigation was performed for the HTLV-I-seropositive donors, and the HTLV-I-seroindeterminate individuals were followed up. RESULTS: Thirty-nine donors (0.4%) were HTLV-I seropositive and 49 (0.5%) were seroindeterminate. The age and sex ratio characteristics of the seroindeterminate donors are divergent from those of the HTLV-I-seropositive group and are more like those of the seronegative population. However, during the study period, three cases of seroconversion after an initial seroindeterminate profile were reported. Two cases were detected through follow-up of 38 HTLV-I-seroindeterminate donors over a mean of 8 months (2-24 months). The third seroconverter belonged to the HTLV-I-seropositive group and was identified through lookback investigation. This case is atypical, with p19 reactivity for several months before HTLV-I seropositivity. CONCLUSION: These findings indicate that, although HTLV-I-seroindeterminate donors mainly are HTLV-I-noninfected, the rate of seroconversion in a repeat blood donor population from an endemic region must be taken into consideration. Moreover, the case of delayed seroconversion observed in this study suggests the difficulty of counseling seroindeterminate blood donors in endemic regions.     

献血者HBV DNA存在的确认与S蛋白变异特征分析

目的对HBsAg阴性和阳性献血者血样HBV DNA存在的确认并分析隐匿性乙型肝炎病毒S区变异特征。方法使用EIA/NAT方法筛查深圳地区19 397份无偿献血者血样,把109例乙肝不合格样品分成3类(HBs Ag+/NAT+、HBs Ag+/NAT-、HBs Ag-/NAT+),通过跟踪检测,确认为OBI毒株10例、HBV窗口期感染期3例和5例缺失追踪的HBs Ag-/HBV DNA+样品,采用荧光定量聚合酶链反应(QPCR)测定HBV病毒载量,应用NestedPCR技术扩增S基因片段并测定序列,与B/C基因型HBs Ag+/HBV DNA+阳性野毒株序列比对。结果深圳市无偿献血者经乙肝表面抗原胶体金快速试纸筛查后的HBs Ag阳性检出率为0.34%(66/19 397);隐匿性乙型肝炎病毒感染(OBI)的流行率范围为1∶1 939-1∶1 293,HBV窗口期感染流行率范围为1∶6 465-1∶2 424;10例OBI样品其病毒载量介于不能定量至112.0 IU/m L(中位数98.5 IU/m L)。10例OBI样本在S蛋白区(nt215-710)出现随机变异,OBI样品S区氨基酸置换率显著高于野毒株(P0.000 1),有4、2、3个OBI样品分别在CTL表位21-29、86-96、172-180出现L21S(2)、K/R24E(1)、I25M(1)、L88P(2)、S172F/L(2)、V178T(1)变异;OBI非CTL表位免疫区的氨基酸置换率亦显著高于野毒株(P0.05);其中1个OBI样品在nt636发生缺失变异。结论深圳献血者OBI流行率有增高趋势,OBI发生机制与乙型肝炎病毒的S蛋白区变异,特别是免疫活性区的变异密切相关。