Virological characteristics of hepatitis B genotype G/A2 recombination virus in Japan.

AIM: We identified four cases of infection with hepatitis B virus genotype G and A2 recombinant (HBV/G/A2) strains, which were initially overlooked by enzyme immunoassay-based genotyping. The patients were all men who have sex with men (MSM) and inhabited several metropolitan areas of Japan, suggesting that the recombinant strains may be circulating among high-risk groups such as MSM. Here, we investigated the genomic structure and virological properties of the HBV/G/A2 strains. METHODS: Complete genome sequences of the isolates were determined and phylogenetically analyzed. Replication efficiency of HBV/G/A2 was investigated by transfecting plasmids containing 1.24-fold viral genome. The in vivo viral kinetics of HBV/G/A2 were investigated using chimeric mice with humanized livers. RESULTS: Phylogenetic analysis revealed that the four strains were almost identical (>99.7% homologous). The preS2/S region of these strains was highly homologous to that of genotype A2 and the remaining region was almost identical to that of genotype G, reflecting inter-genotypic recombination. Interestingly, in all four cases, genotype A was co-infected as a minor population. In vitro analysis revealed that HBV/G/A2 had a low replication rate. Although detectable viremia was not measurable following the inoculation of HBV/G/A2 into chimeric mice, subsequent superinfection of HBV genotype A greatly enhanced HBV/G/A2 replication and viral spread. CONCLUSION: We found that four cases of HBV/G/A2 recombinant among MSM patients in the metropolitan areas of Japan, and HBV/A co-infections are required for its efficient replication. High-risk groups such as MSM should be carefully tested for infection of genotype G-derived variants.

[Efficacy of Human Immunodeficiency Virus (HIV) Antigen-Antibody Combination Assay as a Screening Test and Factors Causing False-Positivity].

Purpose: We aimed to evaluate the performance of an HIV antigen-antibody combination assay (fourth-generation) by comparing it with second generation assays that detect anti-HIV. Methods: A total of 105,439 HIV screening tests were performed from January 2004 to March 2015; the second - and fourth generation assays were used for 75,302 and 30,137 samples, respectively. Samples positive on a screening test were confirmed by anti-HIV-1 western blotting (WB) and nucleic acid amplification. By the results of confirmation tests, the efficacies of the second and fourth generation assays were estimated. The clinical backgrounds with false-positive samples were examined. Results: Of 75,302 samples, 136(0.18%) were positive by the second-generation assay; 14 were confirmed positives, and 122 were false positives. Of 30,137 samples, 18(0.06%) were positive by the fourth-generation assay; 6 were confirmed positives, and 12 were false positives. The reliability of the positives by fourth-generation assay was significantly improved (p=0.006) Samples form individuals with malignant neoplasms were frequently false positive by both the second and fourth-generation assays. Of 67 samples performed by WB, 10 samples, including 6 from patients with a malignancy, showed indeterminate results. All indeterminate samples were found to have antibodies responding to HIV core protein. Conclusion: The fourth-generation assay had satisfactory reliability of the positives for HIV screening. Antibodies responding to HIV core protein may result in false positive HIV screening tests. [Original]

[Comparative Study for Anti-Hepatitis B Surface Antigen Titers Based on Two Measurement Methods: Using Monoclonal Antibodies Isolated from Hepatitis B Vaccinated Recipients].

BACKGROUND: As anti-hepatitis B surface antigen (anti-HBs) titers vary depending on the measurement methods, we compared two different methods to measure anti-HBs titers in sera and HBs monoclonal antibodies. METHODS: The sera from 182 HB virus-resolved patients who were negative for HBsAg but positive for antiHB core protein (HBc) and/or anti-HBs were obtained. The measurement of anti-HBs was compared using either Lumipulse G1200 or Architect i2000SR. Six different monoclonal antibody (mAbs) clones isolated from healthy individuals inoculated with hepatitis B vaccine Bimmugen (genotype C) were used. RESULTS: A statistically significant correlation in anti-HBs titers was found between the two methods tested (Y = 0.951X + 100.7, R = 0.813, p < 0.001), although anti-HBs titers in 72 samples (39.6%) measured by Architect were less than 50% of that by Lumipulse and 12 (6.6%) were opposite results. Measuring 2 mAbs with HBV neutralizing activity, the titers of the 116 antibody (1.0 µg/mL) were comparable (689.3 mIU/mL by Lumipulse and 440.7 mIU/mL by Architect), whereas those of the 478 antibody (1.0 µg/mL) were much lower by Architect than by Lumipulse (42.6 vs. 818.6 mIU/mL, respectively). Of four other mAbs without HBV neutralizing activity, equal titers were observed for one; two mAbs had less anti-HB titers by Architect; and one was below the cut-off index (< 5 mIU/mL). CONCLUSIONS: Anti-HBs titers measured by Architect are likely to be lower than by Lumipulse, and the potential ability to detect the 478 antibody with neutralizing activity is low, indicating that Architect might underestimate anti-HBs titers. Future studies should standardize the anti-HBs titer measurement system.

[Clinical evaluation of a newly developed high-sensitive detection of hepatitis B virus surface antigen by a semi-automated immune complex transfer chemiluminescent enzyme immunoassay].

AIM: A highly sensitive semi-automated immune complex transfer chemiluminescence enzyme immunoassay (ICT-CLEIA) for the detection of hepatitis B surface antigen (HBsAg) was recently developed. Our aim is to investigate clinical significance of ICT-CLEIA in patients with HBV. METHODS: Of 829 HB carriers in our hospital and 167 commercial panels, performance of ICT-CLEIA(detection range 0.0005-2.5 IU/mL) was compared with two quantitative HBsAg detection systems (Architect HBsAg QT assay [0.05-250 IU/mL] and HISCL HBsAg assay [0.03-2500 IU/mL]) and COBAS TaqMan HBV-DNA assay (CTM, 2.1 Log copies/ml) using serum samples from patients or panels. RESULTS: The ICT-CLEIA had good accuracy and reproducibility. The sensitivity of wild type and HBsAg escape mutants (I126S, D144A, G145R) by ICT-CLEIA was 2- -5 to 2- -6 times higher than that of Architect HBsAg QT. For clinical practice, ICT-CLEIA assay could detect HBsAg even in the presence of anti-HBs during window periods in acute hepatitis B panel. HBsAg has been detectable for around 9 years in a patient with HBsAg clearance by Architect. In a patient with HBV reactivation after bone marrow transplantation followed by systematic chemotherapy, HBsAg by ICT-CLEIA was detectable at the same time point when HBV-DNA was detected by PCR. In conclusion, the ICT-CLEIA assay permits not only an earlier detection of acute hepatitis B infection but also may be useful for monitoring hepatitis B patients.

Development of new IL28B genotyping method using Invader Plus assay.

IL28B polymorphism is associated with the response to pegylated interferon-α with ribavirin (PEG-IFN-α/RBV) treatment in chronic hepatitis C patients. As a genotyping assay for IL28B single nucleotide polymorphisms (SNPs) in clinical practice, the Invader Plus assay was developed. The accuracy, intra-assay, inter-assay precision, and the limit of detection of the Invader Plus assay were evaluated. Two SNPs (rs8099917 and rs12979860) associated with IL28B were genotyped by the Invader Plus and TaqMan assay in 512 Japanese patients. In comparison with direct sequencing, the Invader Plus assay showed 99% accuracy in rs8099917 and 100% accuracy in rs12979860. Intra-assay and inter-assay precision were sufficient to use in clinical practice and the detection limit was 1ngDNA/assay. Genotyping by rs8099917 showed that 361 (71%), 144 (28%) and seven (1%) of the patients were major homozygous, heterozygous and minor homozygous types, respectively. Five of the 512 cases (1%) had haplotype differences, but none showed differences between the two genotyping methods. For patients with HCV genotype 1, the prevalence of responders in the major homozygous type was 83.3%, and that of non-responders in the minor heterozygous/homozygous type was 72.5%. A convenient IL28B genotyping method using the Invader Plus assay could be useful to predict the treatment outcome in clinical practice.

The rs8099917 polymorphism, when determined by a suitable genotyping method, is a better predictor for response to pegylated alpha interferon/ribavirin therapy in Japanese patients than other single nucleotide polymorphisms associated with interleukin-28B.

We focused on determining the most accurate and convenient genotyping methods and most appropriate single nucleotide polymorphism (SNP) among four such polymorphisms associated with interleukin-28B (IL-28B) in order to design tailor-made therapy for patients with chronic hepatitis C virus (HCV) patients. First, five different methods (direct sequencing, high-resolution melting analysis [HRM], hybridization probe [HP], the InvaderPlus assay [Invader], and the TaqMan SNP genotyping assay [TaqMan]) were developed for genotyping four SNPs (rs11881222, rs8103142, rs8099917, and rs12979860) associated with IL-28B, and their accuracies were compared for 292 Japanese patients. Next, the four SNPs associated with IL-28B were genotyped by Invader for 416 additional Japanese patients, and the response to pegylated interferon/ribavirin (PEG-IFN/RBV) treatment was evaluated when the four SNPs were not in linkage disequilibrium (LD). HRM failed to genotype one of the four SNPs in five patients. In 2 of 287 patients, the results of genotyping rs8099917 by direct sequencing differed from the results of the other three methods. The HP, TaqMan, and Invader methods were accurate for determination of the SNPs associated with IL-28B. In 10 of the 708 (1.4%) patients, the four SNPs were not in LD. Eight of nine (88.9%) patients whose rs8099917 was homozygous for the major allele were virological responders, even though one or more of the other SNPs were heterozygous. The HP, TaqMan, and Invader methods were suitable to determine the SNPs associated with IL-28B. The rs8099917 polymorphism should be the best predictor for the response to the PEG-IFN/RBV treatment among Japanese chronic hepatitis C patients.

[Evaluation and application of a newly developed highly sensitive HBsAg chemiluminescent enzyme immunoassay for chronic hepatitis B patients].

AIM: A high sensitive chemiluminescent enzyme immunoassay (CLEIA) was developed for quantitative hepatitis B surface antigen (HBsAg) detection by a combination of monoclonal antibodies, each one for a specific epitope of HBsAg, and by improving the conjugation technique (Matsubara, et al. Transfusion 2009). We modified and automated Matsubara's techniques. Our aim is to evaluate the fundamental performance of our assay (prototype) and to investigate the clinical significance of prototype in patients with hepatitis B virus (HBV) infection. METHODS: We used 226 HBsAg-negative samples and 59 HBsAg-positive samples for evaluation of prototype's accuracy, reproducibility, specificity and sensitivity. We examine correlation between the prototype assay and commercial quantitative HBsAg detection assay (the Abbott ARCHITECT). Performance of prototype was compared with the Abbott ARCHITECT in one chronic hepatitis B patient and one patient with HBsAg seroconversion sequentially. RESULTS: The prototype assay had good accuracy, reproducibility, specificity and sensitivity. There is positive correlation between the prototype and the Abbott ARCHITECT. The sensitivity of the prototype (5 mIU/mL) was approximately 10 fold higher than the Abbott ARCHITECT (50 mIU/ml). The prototype could detect HBsAg at the HBsAg-negative point by Abbott ARCHITECT in these patients. CONCLUSIONS: Automatic highly sensitive HBsAg CLEIA prototype is convenient and precise assay for HBV monitoring.

[Evaluation of high-sensitivity HBsAg quantitative assay for HBV genotype].

The clinical implication of the hepatitis B surface antigen (HBsAg) concentrations has been reported in HBV-infected patients during anti-viral treatment. HBV genotypes A and D are ubiquitous and scattered worldwide, especially northern America as well as Europe, whereas genotypes B and C are common in Asia. The aim of this study was to evaluate a new version of the Sysmex HBsAg quantitative kit based on Chemiluminescence Enzyme Immunoassay. Sera collected from 172 patients infected with any of the four major genotypes A to D (HBV/A, n = 18; B, n = 25; C, n = 84; D, n = 45), including the genotype D cases with weak reaction in the previous version of the kit. The new version of the kit having additional monoclonal antibody, showed improved sensitivity compared to the previous version as well as robust correlation with another quantitative HBsAg assay: the Abbot Architect. Observed during lamivudine therapy, increase in HBsAg and HBV DNA concentrations preceded the aminotransferase (ALT) elevation associated with drug-resistant HBV variant emergence (breakthrough hepatitis). In conclusion, reliability of the Sysmex HBsAg quantitative assay was confirmed for the four HBV genotypes common worldwide. Monitoring of serum HBsAg concentrations in addition to HBV DNA quantification, is helpful in evaluation of the response or resistance to anti-viral therapy.

[Evaluation of serum PIVKA-II by Lumipulse PrestoII assay].

Measurements of serum concentrations of Des-gamma-carboxy Prothrombin (PIVKA-II) are widely used for diagnosing hepatocellular carcinoma (HCC). Recently, in Lumipulsef assay, it was reported that antibodies against alkaline phosphatase (ALP) derived from anti bleeding sheets led false high values of PIVKA-II in the patients with HCC resection. To improve the previous issue, newly developed Lumipulse PrestoII assay was examined. (1) The assay was reliable and positively correlated with the previous assays (Lumipulse f and Picolumi, R = 0.997 and 0.994 (n=115), respectively). (2) Eleven cases, which had false high values of PIVKA-II by the Lumipulsef assay, were examined by the PrestoII assay with excess of inactive ALP. The false high values of 10 cases were improved, but only one was still high. False reactivity of this case was stronger than other cases, more effective adsorption was required. (3) Comparing the absorbent activity of inactive ALP among 6 different kinds, we found inactive ALP with much higher adsorbent activity. When this inactive ALP was applied to assay, false high values of PIVKA-II were improved in all 11 cases. In conclusion, the PrestoII assay, which applies the inactive ALP with high activity, is reliable and useful for clinical screening.

[Evaluation of hepatitis B virus genotyping EIA kit].

Clinical significance of Hepatitis B virus(HBV) genotyping is increasingly recognized. The aim of this study was to evaluate reproducibility, accuracy, and sensitivity of an enzyme immunoassay (EIA) based HBV genotyping kit, which designed to discriminate between genotypes to A, B, C, or D by detecting genotype-specific epitopes in PreS2 region. Using the four genotypes panels, the EIA demonstrated complete inter and intra-assay genotyping reproducibility. Serum specimens had stable results after 8 days at 4 degrees C, or 10 cycles of freezing-thawing. In 91 samples that have been genotyped by DNA sequencing, 87(95.6%) were in complete accordance with EIA genotyping. Of examined 344 HBsAg-positive serum specimens, genotypes A, B, C and D were determined in 26 (7.6%), 62 (18.0%), 228 (66.3%), and 9 (2.6%) cases, respectively. Of 19 (5.5%) specimens unclassified by the EIA, 13 were found to have low titer of HBsAg concentration (< 3 IU/ml), and the other 5 had amino acid mutations or deletions within targeted PreS2 epitopes. The EIA allowed genotyping even in HBV DNA negative samples (96.2%). In conclusion, HBV genotype EIA is reliable, sensitive and easy assay for HBV genotyping. The assay would be useful for clinical use.

[Predicting sustained virological response in chronic hepatitis C patients treated with pegylated interferon and ribavirin using a novel highly sensitive Real-time detection PCR assay].

The Abbott Real Time HCV assay (lower limit of detection 12 IU/ml) was developed as a highly sensitive HCV RNA quantitative assay using real-time detection PCR(RTD-PCR). We assessed whether the new assay more effectively predicts sustained virological response (SVR) than conventional PCR (PCR) in 38 chronic hepatitis patients infected with HCV genotype 1b and treated with pegylated interferon alpha2b plus ribavirin. Sixteen patients reached SVR, 10 patients relapsed, 9 patients did not respond, 3 patients discontinued treatment. Positive predictive value (PPV) for SVR of undetectable HCV RNA at W4, 8, 12 by RTD-PCR and PCR was (100% vs. 100% at W4), (100% vs. 100% at W8), (83.3% vs. 72.7% at W12). HCV RNA undetectable at W12 had a higher PPV for SVR when measured by RTD-PCR than by conventional PCR.

Analysis of fibrinogen variants at gamma387Ile shows that the side chain of gamma387 and the tertiary structure of the gammaC-terminal tail are important not only for assembly and secretion of fibrinogen but also for lateral aggregation of protofibrils and XIIIa-catalyzed gamma-gamma dimer formation.

To examine the role of fibrinogen gamma-chain residue 387Ile in the assembly and secretion of this multichain protein, we synthesized a series of variants with substitution at gamma387 by Arg, Leu, Met, Ala, or Asp. Only the variant gamma387Asp showed impaired synthesis in the cells and very low secretion into the medium. In addition, we performed thrombin-catalyzed fibrin polymerization and factor (F) XIIIa-catalyzed cross-linking of the gamma-chain for 4 variants. The degree of lateral aggregation of protofibrils into fibrin fibers was slightly reduced for gamma387Arg and Ala, and moderately reduced for gamma387Leu and Met. Although the FXIIIa-catalyzed cross-linking for all of the variants was slower than that for gamma387Ile, that of gamma387Arg was much more markedly impaired than that of the others. In summary, our studies demonstrated that the specific residue at gamma387 or the conformation of gamma388-411 residues, but not the length of the gammaC tail, is critical for fibrinogen assembly and subsequent secretion. Moreover, this residue or the conformation is also important for not only the lateral aggregation of fibrin polymers but also the FXIIIa-catalyzed cross-linking of the gamma-chain. Interestingly, our results clearly indicate that the conformations critical for these 2 functions are different from each other.

In vitro fibrin clot formation and fibrinolysis using heterozygous plasma fibrinogen from gammaAsn319, Asp320 deletion dysfibrinogen, Otsu I.

INTRODUCTION: We have reported a heterozygous dysfibrinogenemia, fibrinogen Otsu I, caused by the deletion of gammaAsn319 and gammaAsp320, which was originally identified in the dysfibrinogen Vlissingen/Frankfurt IV (V/FIV) associated with thrombosis. Unlike the V/FIV family, the Otsu propositus showed no thrombotic tendencies. To analyze the relationship between thrombosis and the heterozygous plasma variant fibrinogen, we used purified plasma fibrinogen from the Otsu patient and compared it with a normal control. MATERIALS AND METHODS: Thrombin-induced fibrin clot formation and clot structure were observed by fibrin polymerization and scanning electron microscopy, respectively. For in vitro observation of fibrinolysis, plasmin generation and clot lysis assays were performed by the addition of tissue type plasminogen activation (tPA) and plasminogen. RESULTS AND CONCLUSIONS: Polymerization of Otsu was markedly impaired, while fibrin fibers were much thicker and the density of the bundles of fibrin fibers was less and porous compared with normal. Lysis of the Otsu clot was not significantly different from normal when a tPA and plasminogen mixture was overlaid onto the clots. For Otsu, the penetration of the tPA/plasminogen mixture into the clot was much faster than normal and the protection against plasmin cleavage was impaired; however, tPA-induced plasmin activation of the Otsu fibrin was slower than that of normal fibrin, resulting in a clot lysis of Otsu similar to normal.

In vitro expression demonstrates impaired secretion of the gammaAsn319, Asp320 deletion variant fibrinogen.

The hypodysfibrinogenemia Otsu is caused by the two-residue deletion, gammaAsn319 and gammaAsp320. Analysis of plasma or purified fibrinogen from the heterozygous propositus revealed that the amount of variant gamma-chain was lower than that of normal gamma-chain. In order to examine the basis for this difference, we transfected Chinese hamster ovary cells and established stable cell lines that expressed both chains, gammaDelta/gammaN, only the normal chain, gammaN, and only the variant chain, gammaDelta. We measured fibrinogen concentration of confluent cultures by ELISA. We found the ratios of the concentrations in the media to the concentrations in the cell lysates of gammaDelta, gammaDelta/gammaN, and gammaN-cells were 0.42, 0.60, and 1.00, respectively. We measured the concentrations of the gammaDelta and gammaN chains by densitometric analysis of samples following separation by SDS-PAGE and found the fraction of gammaDelta-chains in cell lysates was always greater than the fraction in the respective culture media. We examined the kinetics of fibrinogen synthesis, assembly and secretion in pulse-chase experiments, and found that the gammaDelta-chain was assembled into intact fibrinogen at a rate similar to assembly of the gammaN-chain into normal fibrinogen, but was secreted into the medium at a slightly slower rate than normal fibrinogen. Considered together, these experiments indicate secretion of the variant fibrinogen was slightly impaired. These results suggest that the reduced level of gammaDelta319,320 fibrinogen in the plasma of the Otsu patient arises from modestly impaired secretion of this variant fibrinogen.

Formation of polar-body-like structures induced in polyspermic starfish oocytes that had been inseminated at the germinal vesicle stage.

Immature starfish oocytes, which are arrested at the first meiotic prophase and contain a large nucleus called the germinal vesicle (GV), are known to accept multiple sperm on insemination. We found that if these polyspermic starfish oocytes are induced to mature, they often form small protrusion(s) adjacent to the first polar body emitted shortly earlier. We refer to these protrusion(s) as 'polar-body-like structures (PLS).' Fluorescent staining of PLS indicated that they were not merely cytoplasmic protrusions, but contained some chromatin. Maturing process of these polyspermic oocytes was examined by immnofluorescent staining, which showed that: (i) numerous sperm asters were observed after the onset of GV breakdown; (ii) before the first polar body (PB1) emission, a complex microtubular structure resembling a multipolar spindle was formed; and (iii) several isolated asters were observed after PB1 emission. These results indicate that PLS formation may be induced by interaction of meiosis-I spindle with paternal centrosomes incorporated at GV stage.