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Abstract Protein induced by vitamin K absence or antagonist-II (PIVKA-II) is avitamin K (VK) deficiency indicator in neonates. However, PIVKA-II detection frequency in neonatal blood at birth and the correlation between PIVKA-II and gestational age are unclear. We retrospectively analyzed infants admitted to our institution between June 1, 2018, and March 31, 2022, whose clinical and PIVKA-II data were available, and classified them into preterm and term infant groups. Overall incidence of PIVKA-II-positive cases (≥ 50 mAU/mL) was 42.8%, including 0.6% apparent VK deficiency (≥ 5000 mAU/mL), 3.1% experimental VK deficiency (1000–4999 mAU/mL), and 10.7% latent VK deficiency (200–999 mAU/mL) cases. Incidence of PIVKA-II-positive cases was significantly higher in the term group than in the preterm group (49.4% vs. 29.7%, p

Abstract Background and Aim The purpose of this study was to analyze factors associated with the overall survival (OS) of atezolizumab/bevacizumab combination therapy for advanced hepatocellular carcinoma (aHCC). We also assessed the OS of patients with ineffective therapy and those who discontinued treatment owing to adverse events (AEs). Methods This retrospective multicenter study involved 139 patients with aHCC who received atezolizumab/bevacizumab combination therapy between November 2020 and September 2022. Results The median duration of treatment was 136.5 days, and the median observation period was 316 days. The overall response rate was 40%, and the disease control rate was 78% according to mRECIST criteria. Grade ≥2 AEs occurred in 63 patients (43%) and led to treatment discontinuation in 16 patients. Multivariate analysis revealed that treatment response and occurrence of grade ≥2 AEs after therapy, as well as low level of albumin‐bilirubin (ALBI) grade and low level of des‐gamma carboxy prothrombin (DCP) before therapy, were extracted as factors that contributed to OS. Log‐rank tests with the Kaplan–Meier method showed significant differences in OS among these factors. The OS of patients who discontinued owing to AEs was significantly shorter than that of other patients. Conclusion Not only factors before therapy but also treatment response and the appearance of AEs are involved in OS for atezolizumab/bevacizumab combination therapy. Although the development of AEs also contributed to OS, appropriate management of AEs is important to avoid discontinuing treatment with this combination.

Immune checkpoint inhibitor (ICI)-induced liver injury (LI) is a common adverse event, but the clinical characteristics based on the classification of hepatocellular injury and cholestatic types are not fully evaluated. This study aims to analyze risk factors and histological findings in relation to the classification of ICI-induced LI. In total, 254 ICI-induced LI patients among 1086 treated with ICIs between September 2014 and March 2022 were classified according to the diagnostic criteria for drug-induced LI (DILI), and their risk factors and outcomes were evaluated. Kaplan–Meier analyses showed that overall survival in patients with hepatocellular-injury-type LI was significantly longer than others (p < 0.05). Regarding pre-treatment factors, the lymphocyte count was significantly higher in patients with ICI-induced LI, especially in hepatocellular-injury-type LI. Gamma glutamyl transferase (γGTP) and alkaline phosphatase (ALP) were also significantly lower in patients with ICI-induced LI (p < 0.05). Multivariate analyses revealed that malignant melanoma, high lymphocyte count, and low ALP levels were extracted as factors contributing to hepatocellular-injury-type LI. The histological findings among 37 patients diagnosed as ICI-induced LI via liver biopsy also revealed that the spotty/focal necrosis was significantly frequent in hepatocellular-injury-type LI, whereas ductular reactions were frequently observed in cholestatic-type LI. It is suggested that the histological inflammation pattern in patients with LI is closely correlated with the type of DILI.

Currently, hepatitis B virus (HBV) core antibody (anti-HBc antibody) and HBV core-related antigen (HBcrAg) are widely used as serum markers for diagnosis based on the HBV core region. This review focused on anti-HBc antibodies and HBcrAg and aimed to summarize the clinical significance of currently used assay systems and the issues involved. While anti-HBc is very significant for clinical diagnosis, the clinical significance of quantitative assay of anti-HBc antibody has been reevaluated with improvements in diagnostic performance, including its association with clinical stage and prediction of carcinogenesis and reactivation. In addition, concerning the new HBcrAg, a high-sensitivity assay method has recently been established, and its diagnostic significance, including the prediction of reactivation, is being reevaluated. On the other hand, the quantitative level of anti-HBc antibody expressed in different units among assay systems complicates the interpretation of the results. However, it is difficult to standardize assay systems as they vary in advantages, and caution is needed in interpreting the assay results. In conclusion, with the development of highly sensitive HBcrAg and anti-HBc antibody, a rapid and sensitive detection assay system has been developed and used in clinical practice. In the future, it is hoped that a global standard will be created based on the many clinical findings.

Abstract Background and Aim Regarding the gut–liver axis, fecal dysbiosis is implicated in the pathogenesis of non‐alcoholic fatty liver disease (NAFLD). The significance of mucosa‐associated microbiota (MAM, which is present in the mucin layer covering the intestinal mucosa) has not been well explored. We aimed to clarify the characteristics of MAM in patients with NAFLD. Methods MAM were obtained from seven patients with early‐stage NAFLD and seven controls by colonoscopy in five locations (terminal ileum, cecum, ascending and sigmoid colon, and rectum) using mucosal brushes. The microbial 16S rDNA profiles of the MAM and fecal microbiota of patients in the NAFLD and control groups were analyzed. Results α‐diversities of fecal microbiota were decreased in patients with NAFLD (observed species, Shannon index, and Chao1: 174.57 vs 134.86, 5.51 vs 4.65, and 206.34 vs 167.91; P = 0.048, 0.067, and 0.087, respectively), and microbial composition analyses by principal coordinate analysis differed between the fecal microbiota of patients with NAFLD and those of controls (permutational analysis of variance [PERMANOVA] of weighted and unweighted: Pseud‐F: 1.4179/P‐value: 0.05 and Pseud‐F: 2.1497/P‐value: 0.049, respectively). However, α‐diversities or microbial composition of MAM in most parts of the intestine did not differ significantly between the NAFLD and control groups. Unclassified Rikenellaceae, Oscillospira, Odoribacter, unclassified clostridiales, and Holdemania were decreased in the feces of patients with NAFLD (determined by linear discriminant analysis effect size), but five (except Holdemania) of the six genera were not decreased in the MAM of these patients. Conclusion In early‐stage NAFLD, MAM was uniform and relatively stable throughout the intestine, even when fecal dysbiosis appeared.

Abstract Background and Aim Molecular‐targeted therapies such as sorafenib and lenvatinib have long been used as first‐line treatment for advanced hepatocellular carcinoma (aHCC). However, adverse events or limited therapeutic effects may necessitate the change to another therapeutic option, known as post‐progression therapy. To investigate the significance of post‐progression therapy, we analyzed the outcomes of aHCC patients following first‐line molecular‐targeted therapy in a real‐world study. Methods This retrospective, multicenter study involved patients with aHCC who received sorafenib or lenvatinib as first‐line therapy between January 2011 and September 2021. Results In total, 513 patients were analyzed: 309 treated with sorafenib and 204 with lenvatinib. The overall response and disease control rates were 15 and 50%, respectively, in the sorafenib group and 30 and 75%, respectively, in the lenvatinib group (P

Objectives: Rapid plasma reagin (RPR) and Treponema pallidum (TP) antibody test kits are often used to diagnose syphilis, although the relationship between their measured values is unclear. We aimed to reveal the relevance of these kits’ results. Design and methods: In all, 143 sera from 110 patients were tested using 12 TP kits and 5 RPR kits and the results compared. Results: The specificity and sensitivity of RPR kits were 81–96% and 95–100%, respectively. The correlation coefficients (0.849–0.934) considerably differed between the manual RPR card test and latex agglutination (LA) assay kits. The following sensitivities were obtained: 82–91% for TP fluorescent treponemal antibody absorption assay (FTA-ABS), TP hemagglutination assay (HA), and TP particle agglutination assay (PA); 94–95% for TP LAs; and 92–100% for chemiluminescent immunoassay (CLIA), chemiluminescent enzyme immunoassay (CLEIA), and immunochromatography assay (IC). Correlation coefficients between TP kits were 0.753–0.974, and the measured values varied. Changes in RPR and quantifiable TP kits were the same for patients with reinfected syphilis and with syphilis under treatment. Conclusions: RPR tests had lower specificity than TP antibody tests. RPR card test and RPR LAs had similar specificity and sensitivity, but their measured values were different. RPR should be measured using automatic RPR LA without setting the upper limit of the reported value. RPR LA should also be standardized. The sensitivity of TP antibody was better in CLIA, CLEIA, and IC than in FTA-ABS, HA, PA, and LA. Therefore, TP antibody kits should be standardized and quantified.

The natural ingredient-based therapy extracted from various plants is assumed more tolerable to cancer patients' bodies than synthetic drugs. To tell successful novel cancer therapy, an indicator is needed to confirm the result. VEGF is a pro-angiogenic factor that leads the cancer cells' invasion to another organ and is associated with high mortality in patients. Hence, the VEGF level is widely used as one of the successful cancer therapy indicators. Purposed of research elucidated the effect of Mandarin orange peel ethanol extract (EEKJM) to improve the reduction of VEGF levels in colon cancer in vitro. This study was an experimental posttest and control group design to analyze different level of VEGF on cancer cells at end of the study. Research began with the preparation of EEKJM followed by a cytotoxic extract test using the MTT assay method. Furthermore, the measurement of VEGF levels by the VEGF ELISA kit protocol. One Way ANOVA was performed to analyze data. Results showed the cytotoxic test of the EEKJM and doxorubicin against WiDr cells was 240 g/ml and 1.59 µg/ml. VEGF levels showed decreasing after being induced with EEKJM and doxorubicin with doses ½ IC50 and ¼ IC50. Conclusion: EEKJM was able to reduce VEGF levels and viability of WiDr colon cancer cells. The advantages are as much as initial evidence of the ability of the orange to treat cancer even though further animal studies or evidence of a pathway of decrease of the VEGF or other signals are required. [ABSTRACT FROM AUTHOR]

Objective: To examine the potential risk of hepatitis B virus (HBV) spread in Indonesia by migrant workers, based on the molecular characteristics of HBV strains. Methods: Sera collected from migrant workers traveling to their destination countries (pre-migrant workers) and those returning to Indonesia (post-migrant workers) were screened for HBsAg by ELISA, followed by HBV DNA detection by PCR and (sub) genotype/subtype determination according to surface region and whole genome sequencing. Results: Of 87 pre-migrant workers, 15 (17.24%) were HBsAg-positive, whereas 15 (12.10%) of 124 post-migrant workers were HBsAg seropositive. HBV genotype analysis based on the S region showed that HBV-B3/adw2 was predominant (96.15%, 25/26) whereas 3.85% (1/26) of isolates were HBV-C3/adrq+. Whole genome sequencing of selected strains and phylogenetic tree analysis identified subgenotype B7 in three samples previously categorized as subgenotype B3 based on S region analysis, supporting a recent argument that subgenotypes B5/B7/B8/B9 could be considered as a quasi-subgenotype of B3. Conclusions: A high prevalence of HBsAg carriers was detected among migrant workers from Lombok Island, with no significant difference in prevalence between before and after returning to Indonesia. All strains were classified into genotypes common in Indonesia, and the results suggested that migrant workers are not a risk factor for HBV transmission into Indonesia.

Abstract Background A large-scale Japanese study showed that low skeletal muscle index (SMI) and intramuscular fat (IMF) deposition are associated with hepatocellular carcinoma (HCC) survival. Here, we evaluated the effects of SMI and IMF on the survival of Indonesian HCC patients, whose characteristics differ from those of Japanese patients. Methods SMI and mean muscle attenuation (MA) were evaluated using computed tomography images of the third lumbar vertebra (L3) in a prospective cohort of 100 Indonesian HCC patients. Clinical, laboratory and body composition data were analysed using the Kaplan–Meier method and Cox regression model to investigate which factors are associated with prognosis. Results Of 100 patients, 31 were diagnosed with sarcopenia (L3 SMI value ≤36.2 cm2/m2 for men and ≤ 29.6 cm2/m2 for women), and 65 had IMF deposition (MA value ≤44.4 HU for men and ≤ 39.3 HU for women). These groups had shorter median survival than the reference groups (both P

Abstract Background Hepatocellular carcinoma (HCC) can develop in patients who are negative for the hepatitis B surface antigen (HBsAg) in serum but positive for hepatitis B virus (HBV) DNA in the liver, referred to as occult HBV infection (OBI). Previous reports showed that HBV variants in OBI-related HCC are different from those in HBsAg-positive HCC. In the present study, HBV quasispecies based on the pre-S/S gene in OBI-related HCC patients were examined by high throughput sequencing and compared with those in HBsAg-positive HCC. Methods Nineteen tissue samples (9 OBI-related and 10 HBsAg-positive non-cancerous tissues) were collected at the time of surgery at Kobe University Hospital. The quasispecies with more than 1% variation in the pre-S/S region were isolated and analysed by ultra-deep sequencing. Results There were no significant differences in the major HBV populations, which exhibit more than 20% variation within the entire pre-S/S region, between OBI-related HCC and HBsAg-positive HCC. However, the prevalences of major populations with pre-S2 region mutations and of minor populations with polymerized human serum albumin-binding domain mutations were significantly higher in OBI-related HCC than in HBsAg-positive HCC. Moreover, the major variant populations associated with the B-cell epitope, located within the pre-S1 region, and the a determinant domain, located in the S region, were detected frequently in HBsAg-positive HCC. The minor populations of variants harbouring the W4R, L30S, Q118R/Stop, N123D and S124F/P mutations in the pre-S region and the L21F/S and L42F/S mutations in the S region were detected more frequently in OBI-related HCC than in HBsAg-positive HCC. Conclusions Ultra-deep sequencing revealed that the B-cell epitope domain in the pre-S1 region and alpha determinant domain in the S region were variable in HBsAg-positive HCC, although the quasispecies associated with the pre-S2 region were highly prevalent in OBI-related HCC. Trial registration Ref: R000034382/UMIN000030113; Retrospectively registered 25 November 2017.

Abstract Background Occult hepatitis B infection (OBI) is defined as the presence of hepatitis B virus (HBV) DNA in the serum and/or liver in HBsAg-negative individuals. OBI is associated with the risk of viral transmission, especially in developing countries, and with progressive liver disease and reactivation in immunosuppressive patients. The objective of this study was to evaluate the relation of OBI to HLA-DP single nucleotide polymorphisms (SNPs) encoding antigen-binding sites for the immune response to HBV infection. As HLA-DP variants affect the mRNA expression of HLA-DPA1 and HLA-DPB1 in the liver, we hypothesised that high levels of HLA-DPA1 and HLA-DPB1 expression favour OBI development. Methods The study enrolled 456 Indonesian healthy blood donors (HBsAg negative). OBI was defined as the presence of HBV-DNA in at least two of four open reading frames (ORFs) of the HBV genome detected by nested PCR. SNPs in HLA-DPA1 (rs3077) and HLA-DPB1 (rs3135021, rs9277535, and rs2281388) were genotyped using real-time Taqman® genotyping assays. Results Of 122 samples positive for anti-HBs and/or anti-HBc, 17 were determined as OBI. The minor allele in rs3077 was significantly correlated with OBI [odds ratio (OR) = 3.87, 95% confidence interval (CI) = 1.58–9.49, p = 0.0015]. The prevalence of the minor allele (T) was significantly higher in subjects with OBI than in those without (59% and 33%, respectively). The combination of haplotype markers (TGA for rs3077–rs3135021–rs9277535) was associated with increased risk of OBI (OR = 4.90, 95%CI = 1.12–21.52 p = 0.038). The prevalence of OBI was highest in the isolated anti-HBc group among the three seropositive categories: anti-HBs

The VEGF gene polymorphism rs699947 related to clinical pathology, mortality, and recurrence of HCC. Few studies mentioned an association between VEGF gene polymorphisms with illness progression in chronic liver disease. We aimed to explore differences of VEGF gene polymorphism rs699947 in chronic hepatitis, liver cirrhosis and hepatocellular carcinoma patients in Indonesian population.A cross-sectional study with consecutive sampling and without matching was performed during a 3 years period (2011-2014) at Dr. Sardjito General Hospital Yogyakarta, Indonesia. Blood DNA was sequenced from 123 subjects with chronic liver diseases [39 chronic hepatitis (CH), 39 liver cirrhosis (LC), and 45 hepatocellular carcinoma (HCC)]. 59 healthy subjects also participated. Using isolated VEGF genes for specific primers for rs699947, blood samples were examined by targeting DNA sequences with Applied Bio systems. All data were analyzed using STATA version 11.0 with significance level at P0.05). HBV was the dominant etiology in HCC, LC, and CH besides HCV and non HBV-HCV (PC vs. C>C, and genotypes distribution. Proportion of SNP -2578 A>C vs. C>C CH 1.8:1; HCC 1.4:1; healthy 1.7:1; but its proportion in LC was inversed (1:1.2). Genotype A was low in all subjects (5%-11%). Significant difference of allele distribution was found in healthy vs. LC, and HCC; CH vs. LC. Based on HWE analyses, distribution of allele C was dominant. There were not significant differences in deletion, insertion-deletion at -2547 until -2526, and haplotype (Ht) CCGACCCC (P>0.05). The OR analyses of allele and SNP showed that allele A can be a predictor of disease progression in LC to HCC (OR 2.26) and healthy to LC (OR 1.65); and SNP A>C also can be a predictor in healthy to HCC (OR 1.41) and CH (OR 1.14).The occurrence of allele A and SNP A>C VEGF gene (-2578) might predict illness progression from healthy to CH, LC or HCC and LC to HCC.

The patient was a 43-year-old man with chronic hepatitis B without history of hepatocellular carcinoma (HCC), who was first diagnosed with thrombosis in right portal vein trunk and portal vein branches and ruptured esophageal varices in October 2011. He underwent endoscopic variceal ligation, but ruptured repeatedly. Despite anti-coagulant therapy, the thrombosis expanded from right portal vein trunk to upper mesenteric vein in March 2012. Computed tomography (CT) scan showed that portal vein thrombosis had low density from early to late phase. No focal liver lesions were identified by CT scan or ultrasound, and alpha-fetoprotein (AFP) was within normal range. He died by intractable esophageal variceal bleeding in April 2012. Pathological examination of autopsy specimen showed that portal vein thrombosis was consistent with poorly-differentiated HCC. The portal vein tumor thrombosis (PVTT) had only a few tumor vessels, which were compressed by fibromatous change originating from HCC formation, so were represented as low-density lesions from arterial to portal phase of CT. In addition, PVTT was negative for AFP, so representing serum value of AFP within normal range. PVTT had positive staining for c-kit, which is a liver stem cell marker. Liver tumors in the whole liver parenchyma were not found pathologically. PVTT might have the characteristics of presumed liver cancer stem cells. We experienced the first case of HCC only in portal vein without liver parenchyma tumor nodules, with difficult differential diagnosis from a non-malignant portal vein thrombosis. We also reported new tumor profiles of the portal venous tumor growth- type of HCC.

Mutations of precore (A1896) and core promoter (T1762/A1764) of hepatitis B virus can reduce HBeAg production. These mutations are frequently found in the late HBeAg seroconversion. However, it has been a controversy about the role played by precore and core promoter mutations in determining outcome of chronic hepatitis B. In the present study, the variability of precore and core promoter of hepatitis B virus were analyzed using PCR amplification and sequencing, according to the outcome (viral load and HBeAg/anti-HBe) in chronic hepatitis B patients in Surabaya. The study groups included 5 patients with uncomplicated chronic hepatitis B and 10 patients with chronic hepatitis B and liver cirrhosis in Dr. Soetomo Hospital, Surabaya. The control group included 6 blood donors obtained from Indonesia Red Cross, Surabaya. All groups were HBsAg positive. Precore mutation A1896 was predominant in all groups (60%-67% of each), together with precore variant T1858. As reported, precore variant T1858 is a prerequisite for precore A1896 and characteristic for viral genotype. Nevertheless, core promoter mutations T1762/A1764 were predominant only in LC patients (60%). All of these mutations were found mostly after HBeAg seroconversion (anti-HBe+). Of most samples with anti-HBe+, precore mutation was related with low viral load (105 copies/mL). Precore mutation A1896 was predominant in all groups, but core promoter mutations T1762/A1764 were only predominant in LC patients. The precore mutation alone is possible not critical to indicate a poor outcome, the core promoter mutations must be considered also.

The prevalence of hepatitis C virus (HCV) infection has been as high as approximately 80% in patients with maintenance hemodialysis in public hospitals in Indonesia. However, the prevalence in private hospitals has not been examined yet. The aim of this study was to investigate the prevalence of anti-HCV antibody and the subtype distribution in patients with hemodialysis in a private hospital in Surabaya, Indonesia. Sera were obtained from 41 hemodialysis patients in a private hospital in Surabaya. The positive prevalence of anti-HCV antibody was carried out by the enzyme-linked immunosorbent assay (ELISA). Anti-HCV-positive sera were subjected to reverse transcription-PCR (RT-PCR) to detect HCV RNA and then direct sequencing. The HCV subtype was examined by phylogenetic analysis. Twenty five patients (61%) out of 41 were positive for anti-HCV antibody, and HCV-RNA was detected in 19 patients. The positive prevalence of anti-HCV antibody was 7.7% (one out of 13 patients) among patients who had undergone hemodialysis for less than one year, whereas it was 85.7% (24 out of 28 patients) among patients who had undergone hemodialysis for over one year. Phylogenetic analysis revealed HCV-1a (52.6%) was the most common subtype, followed by 1b (15.8%), 1c (15.8%), 2a (5.3%), and 3k (5.3%). In conclusion, the prevalence of HCV infection among hemodialysis patients in a private hospital was as high as that in general hospitals. The predominant subtype was HCV-1a, which is in accordance with the previous studies in general hospitals in Surabaya, Indonesia.

Pregenomic RNA (pgRNA) is generated from covalently closed circular DNA (cccDNA) and plays important roles in viral genome amplification and replication. Hepatic pgRNA and cccDNA expression levels indicate viral persistence and replication activity. This study was aimed to measure hepatic pgRNA and cccDNA expression levels in various states of hepatitis B virus (HBV) infection. Thirty-eight hepatocellular carcinoma (HCC) patients, including 14 positive for hepatitis B surface antigen (HBsAg) and 24 negative for HBsAg but positive for anti-hepatitis B core (anti-HBc) antibody, were enrolled in this study. In HBsAg-negative but anti-HBc-positive group, HBV-DNA was detected in 20 of 24 (83%) noncancerous liver tissues for at least two genomic regions based on polymerase chain reaction (PCR) analysis. pgRNA and cccDNA expression levels in occult HBV-infected patients were significantly lower than those in HBsAg-positive patients (P

BACKGROUND: Transcatheter arterial chemoembolization (TACE) is an effective treatment for hepatocellular carcinoma (HCC) that can occasionally lead to the shortening of life expectancy. We aimed to make a new and more accurate prognostic model taking into account the course of disease after TACE. METHODOLOGY/PRINCIPAL FINDINGS: We performed a prospective cohort study involving 100 HCC patients who underwent TACE at Kobe University Hospital. Indirect calorimetry and blood biochemical examinations were performed before and 7 days after TACE. Time-dependent and time-fixed factors associated with 1-year mortality after TACE were assessed by multivariate analyses. A predictive model of 1-year mortality was established by the combination of odds ratios of these factors. Multivariate analyses showed that the ratio of non-protein respiratory quotient (npRQ) (7 days after/before TACE) and Cancer of Liver Italian Program (CLIP) score were independent factors of 1-year mortality after TACE (p = 0.014 and 0.013, respectively). Patient-specific 1-year mortality risk scores can be calculated by summarizing the individual risk scores and looking up the patient-specific risk on the graph. CONCLUSIONS: The short-term reduction of npRQ was a time-dependent prognostic factor associated with overall survival in HCC patients undergoing TACE. CLIP score was a time-fixed prognostic factor associated with overall survival. Using the prediction model, which consists of the combination of time-dependent (npRQ ratio) and time-fixed (CLIP score) prognostic factors, 1-year mortality risk after TACE would be better estimated by taking into account changes during the course of disease.

Pegylated-interferon plus ribavirin (PEG-IFN/RBV) therapy is a current standard treatment for chronic hepatitis C. We previously reported that the viral sequence heterogeneity of part of NS5A, referred to as the IFN/RBV resistance-determining region (IRRDR), and a mutation at position 70 of the core protein of hepatitis C virus genotype 1b (HCV-1b) are significantly correlated with the outcome of PEG-IFN/RBV treatment. Here, we aimed to investigate the impact of viral genetic variations within the NS5A and core regions of other genotypes, HCV-2a and HCV-2b, on PEG-IFN/RBV treatment outcome. Pretreatment sequences of NS5A and core regions were analyzed in 112 patients infected with HCV-2a or HCV-2b, who were treated with PEG-IFN/RBV for 24 weeks and followed up for another 24 weeks. The results demonstrated that HCV-2a isolates with 4 or more mutations in IRRDR (IRRDR[2a]≥4) was significantly associated with rapid virological response at week 4 (RVR) and sustained virological response (SVR). Also, another region of NS5A that corresponds to part of the IFN sensitivity-determining region (ISDR) plus its carboxy-flanking region, which we referred to as ISDR/+C[2a], was significantly associated with SVR in patients infected with HCV-2a. Multivariate analysis revealed that IRRDR[2a]≥4 was the only independent predictive factor for SVR. As for HCV-2b infection, an N-terminal half of IRRDR having two or more mutations (IRRDR[2b]/N≥2) was significantly associated with RVR, but not with SVR. No significant correlation was observed between core protein polymorphism and PEG-IFN/RBV treatment outcome in HCV-2a or HCV-2b infection.The present results suggest that sequence heterogeneity of NS5A of HCV-2a (IRRDR[2a]≥4 and ISDR/+C[2a]), and that of HCV-2b (IRRDR[2b]/N≥2) to a lesser extent, is involved in determining the viral sensitivity to PEG-IFN/RBV therapy.