Evaluation of the limiting antigen avidity EIA (LAg) in people who inject drugs in Greece.

This analysis assessed the utility of the limiting antigen avidity assay (LAg). Samples of people who inject drugs (PWID) in Greece with documented duration of HIV-1 infection were tested by LAg. A LAg-normalized optical density (ODn) ⩽1·5 corresponds to a recency window period of 130 days. The proportion true recent (PTR) and proportion false recent (PFR) were estimated in 28 seroconverters and in 366 samples collected >6 months after HIV diagnosis, respectively. The association between LAg ODn and HIV RNA level was evaluated in 232 persons. The PTR was 85·7%. The PFR was 20·8% but fell to 5·9% in samples from treatment-naive individuals with long-standing infection (>1 year), and to 0 in samples with the circulating recombinant form CRF35 AD. A LAg-based algorithm with a PFR of 3·3% estimated a similar incidence trend to that calculated by analyses based on HIV-1 seroconversions. In recently infected persons indicated by LAg, the median log10 HIV RNA level was high (5·30, interquartile range 4·56-5·90). LAg can help identify highly infectious HIV(+) individuals as it accurately identifies recent infections and is correlated with the HIV RNA level. It can also produce reliable estimates of HIV-1 incidence.

Development and assessment of a novel real-time PCR assay for quantitation of hepatitis D virus RNA to study viral kinetics in chronic hepatitis D.

Hepatitis delta virus (HDV) infection is a usually severe type of viral hepatitis associated with increased mortality and rapid evolution to cirrhosis. Currently, treatment is limited to extended interferon administration and measurement of HDV RNA blood levels is essential to judge the response. The aim of this study was to develop a highly sensitive and reproducible real-time reverse transcriptase-polymerase chain reaction (real-time RT-PCR) for the quantitation of circulating HDV RNA of all clades (1-8), and assess its usefulness in the follow-up of patients. The amplification was combined with molecular beacon technology using the LightCycler 2.0 system. The assay was specific and showed linearity over a wide range from 13 to 13 × 10(10) copies/mL. The 95% detection limit was 43.2 copies/mL. Intra-assay reproducibility, as expressed by the coefficient of variation, ranged from 1.84 to 18.61%, whereas the corresponding estimates for the inter-assay variability ranged from 0.57 to 10.18%. Finally, the dynamic profiles of six patients regarding virological (HDV RNA, HBV DNA), biochemical and serological data were constructed. We were able to observe that most patients who were treated with an interferon-based regime showed a significant reduction in delta viremia. In conclusion, our real-time RT-PCR for HDV RNA quantification combines high sensitivity and reproducibility in a high dynamic range, can provide important information for patient management and can be a useful tool for monitoring the response to antiviral therapies.

Detection of specific antibodies to HCV-ARF/CORE+1 protein in patients treated with pegylated interferon plus ribavirin.

Hepatitis C virus (HCV) infection is a major cause for chronic liver disease and hepatocellular carcinoma. The HCV-ARF/core+1 protein is an alternative product of HCV core-encoding sequence of unknown biological function. Highly purified HCV core and ARF/core+1 recombinant proteins from HCV genotype 1a and HCV-ARF/core+1 recombinant protein from HCV genotype 3a were expressed in Escherichia coli. Using an enzyme-linked immunosorbent assay, we assessed the prevalence of anti-ARF/core+1 antibodies in 90 chronic hepatitis C patients infected with HCV genotypes 1a/1b or 3a, treated with pegylated interferon (Peg-IFN-a-2a) plus ribavirin. Samples derived from 92 healthy blood donors were used as negative controls. All HCV-RNA-positive serum samples reacted with core 1a antigen, while 15 (37.5%) of 40 and 14 (28%) of 50 patients infected with HCV-1a/1b and HCV-3a, respectively, were found to have anti-ARF/core+1 antibodies into their serum before treatment initiation. These antibodies were persistently present during treatment follow-up and linked to elevated levels of HCV-RNA at baseline.

Analytical and clinical sensitivity of the Procleix Ultrio HIV-1/HCV/HBV assay in samples with a low viral load.

BACKGROUND AND OBJECTIVES: The Procleix Ultrio human immunodeficiency virus type 1 (HIV-1)/hepatitis C virus (HCV)/hepatitis B virus (HBV) (Ultrio) assay simultaneously detects HIV-1 RNA, HCV RNA and HBV DNA in individual blood donations. The main objective of the study was to assess the analytical and clinical sensitivity of the multiplex and discriminatory probe assays in samples with a low viral load. MATERIAL AND METHODS: The VQC HIV RNA genotype B, HCV RNA genotype 1 and HBV DNA genotype A standard dilutions were tested in 26 repeats. The probability of detection by Ultrio was compared with previously obtained data of the Procleix Duplex HIV-1/HCV assay on the same reference panels. A selection of 121 anti-HIV-1, 138 anti-HCV and 190 HBsAg positive samples from patients receiving antiviral therapy were tested. The majority of patient samples had a viral load below the detection limit of the diagnostic nucleic acid test assays, which made them suitable to evaluate the performance of the multiplex and discriminatory assays on yield cases with a similar low viral load. RESULTS: The 95% and 50% detection end-points of the Ultrio assay along with the corresponding 95% confidence intervals are 53.7 (32.9-117.2) and 8.6 (6.2-12.1) geq/ml for HIV-1 RNA, 30.3 (19.0-62.4) and 5.2 (3.7-7.2) geq/ml for HCV RNA and 393.7 (147.9-6978) and 54.5 (22.4-143.8) geq/ml for HBV DNA. The analytical sensitivity of Ultrio expressed as a potency factor relative to previously obtained Duplex results on the same HIV-1 RNA and HCV-RNA standard dilutions was 1.09 (0.20-6.10) and 1.11 (0.21-5.89), respectively. The assay detected all 22 HIV-1 infected patients with viral load > 50 copies/ml, and 41 of 99 patients (41%) with viral load < 50 copies/ml, of which 23 (56%) were detected by the discriminatory assay. All 47 patients with HCV RNA load > 521 IU/ml and 10/91 polymerase chain reaction-negative patients with viral load < 50 IU/ml tested positive in Ultrio assay of which five were missed in the discriminatory test. The assay detected 53/55 HBV infected patients (96%) with viral load > 250 copies/ml and 108/135 patients (80%) with viral load < 250 copies/ml of which 17 (16%) were missed by the discriminatory test. CONCLUSIONS: The new Procleix Ultrio assay is as sensitive as the Procleix Duplex assay for HIV-1 and HCV detection meeting the requirements of universal guidelines. The ability of the assay to detect HBV DNA in low viral load samples could be useful for screening blood. Inevitable negative results of discriminatory probe assays caused by stochastic sample variation will reduce the chance of recognizing low viraemic blood donors detected by individual donation nucleic acid test.

Molecular epidemiology of hepatitis C virus (HCV) in Greece: temporal trends in HCV genotype-specific incidence and molecular characterization of genotype 4 isolates.

This study aimed to estimate the overall HCV genotype distribution and to reconstruct the HCV genotype-specific incidence in Greece during the recent decades. It also focused at the identification of genotype 4 subtype variability in Greek isolates. A total of 1686 chronically infected HCV patients with detectable serum HCV RNA by RT-PCR, belonging to different risk groups were studied. Amplified products from the 5'-noncoding region were typed using a commercially available assay based on the reverse hybridization principle. The HCV genotype-specific incidence was estimated using a previously described back calculation method. HCV genotype 1 was the most prevalent (46.9%) followed by genotype 3 (28.1%), 4 (13.2%), 2 (6.9%) and 5 (0.4%). A high prevalence of genotype 1 (66.3%) in haemophilia patients was recorded whereas HCV genotype 3 was found mainly among patients infected by I.V. drug use (58.2%). Data on the temporal patterns of HCV genotype-specific incidence in Greece revealed a moderate increase (1.3-1.6 times) for genotypes 1 and 4, and a decrease (1.5 times) for genotype 2 from 1970 to 1990, whereas there was a sharp (13-fold) increase for genotype 3. The molecular characterization of 41 genotype 4 HCV isolates belonging to various risk groups revealed that, subtype 4a was the most frequently detected (78%). Phylogenetic comparison of the Greek 4a isolates with all HCV-4a isolates reported worldwide so far revealed a topology which does not discriminate Greek isolates from the others. HCV-4 does not represent a recent introduction in Greece.

Prevalence of resistance-associated mutations in newly diagnosed HIV-1 patients in Greece.

The prevalence of HIV-1 drug resistance mutations in naïve patients has been previously shown to differ greatly with the geographic origin. The purpose of this study was to prospectively estimate the prevalence of HIV-1 drug resistance in Greece by analyzing a representative sample of newly HIV-1 diagnosed patients, as part of the SPREAD collaborative study. Protease (PR) and partial reverse transcriptase (RT) sequences were determined from 101 newly diagnosed HIV-1 patients, in Greece, during the period September 2002--August 2003, representing one-third of the total newly diagnosed HIV-1 patients in the same time period. The prevalence of HIV-1 drug resistance was estimated according to the IAS-USA mutation table taking into account all mutations in RT and only major mutations in PR region. The overall prevalence of resistance was 9% [95% confidence interval (CI): 4.2--16.2%]. The prevalence of mutations associated with resistance to NRTIs was 5% (95% CI: 1.6--11.2%), for NNRTIs was 4% (95% CI: 1.1--9.8%), while no major resistance mutations were found in PR. No multi-class resistance was detected in the study population. The prevalence of resistant mutations in the recent seroconverters was 22%. For two individuals, there was clear evidence for transmitted resistance based on epidemiological information for a known source of HIV-1 transmission. The prevalence of the HIV-1 non-B subtypes and recombinants was 52%.

Prevalence and genotypic distribution of TT virus in Athens, Greece.

The prevalence of TT virus (TTV) infection in various population groups from Athens, Greece, was assessed by the polymerase chain reaction (PCR) using two primer sets from distinct regions of the genome: the conventional set derived from the open reading frame-1 (ORF-1) and the new, highly sensitive set targeting the region that includes the TATA signal localized upstream of ORF-2. Based on both primer sets, TTV DNA was detected in 42/50 (84.0%) healthy individuals, 42/50 (84.0%) chronic hepatitis C patients, 31/39 (79.5%) acute non-A-E hepatitis patients (group I), 14/16 (87.5%) renal failure patients with acute non-A-E hepatitis (group II), 47/50 (94.0%) intravenous drug users (IVDU), 36/50 (72.0%) hemophiliacs, and 21/31 (67.7%) hemodialysis patients. The presence of TTV was not associated with any particular risk group, and no differences were observed in relation to demographic, biochemical and virological characteristics between TTV DNA-positive and -negative patients. TTV did not seem to have a profound effect on the course of chronic C or acute non-A-E hepatitis either. Phylogenetic analysis revealed that TTV strains circulating in the greater metropolitan area of Athens belong not only to the G1 and G2 genotypes that are encountered worldwide, but also to G3 and to G5 that are found mainly in Europe and Asia, respectively. Further studies will shed light on the role of this highly prevalent virus.

Comparative evaluation of the QUANTIPLEX HIV-1 RNA 2.0 and 3.0 (bDNA) assays and the AMPLICOR HIV-1 MONITOR v1.5 test for the quantitation of human immunodeficiency virus type 1 RNA in plasma.

HIV-1 RNA measurements from 84 plasma specimens obtained with the QUANTIPLEX HIV-1 RNA 2.0 and 3.0 (bDNA) assays (Chiron Diagnostics, Emeryville, CA) and with the AMPLICOR HIV-1 MONITOR Test, version 1.5 with ultra-sensitive specimen preparation (Roche Diagnostic Systems, Inc., Branchburg, NJ) were compared. The absolute RNA values of tested specimens differed significantly between bDNA 2.0 and bDNA 3.0 or Monitor v1.5 measurements (Wilcoxon signed-rank test P<0.001). Results generated with bDNA 3.0 or with Monitor v1.5 were approximately twofold greater than those generated with bDNA 2.0, with smaller differences at higher HIV-1 RNA levels and greater differences at RNA levels below 1000 copies per ml. Although highly correlated (r=0.92 and 0.86, respectively), viral load data generated with bDNA 2.0 and either bDNA 3.0 or Monitor v1.5 were in poor agreement. Concordant results (difference in log(10) copies per ml <0.5) were found at frequencies of 80% for bDNA 2.0 and bDNA 3.0 and only at 58.5% for bDNA 2.0 and Monitor v1.5. In contrast, bDNA 3.0 and Monitor v1.5 measurements were highly correlated (r=0.96) and in good agreement (92.7%).

Molecular epidemiology of a hepatitis C virus outbreak in a haemodialysis unit. Multicentre Haemodialysis Cohort Study on Viral Hepatitis.

BACKGROUND: Haemodialysis patients are at high risk of infection by hepatitis C virus. The aim of this study was to investigate a hepatitis C virus outbreak which occurred in a haemodialysis unit, using epidemiological and molecular methods. METHODS: Five seroconversions to hepatitis C virus antibody (anti-HCV) were observed over a 6 month period and these were added to the four previously recorded anti-HCV-positive patients. All nine patients involved in the outbreak were tested for HCV RNA by reverse transcription-polymerase chain reaction and hepatitis C genotype determination was accomplished by a reverse hybridization assay. Furthermore, part of the NS5 region of hepatitis C genome (nucleotide positions 7904-8304) was amplified and sequenced in all HCV RNA-positive patients. Then, phylogenetic analysis of the nucleotide sequences obtained was carried out in order to investigate any possible epidemiological linkage among patients. Detailed epidemiological records were also available for all haemodialysis patients. RESULTS: Samples from all five incident cases and three out of four prevalent HCV infections were found positive for HCV RNA. HCV genotyping studies revealed that all incident cases were classified as 4c/d, whereas one and two prevalent cases were 1a and 4c/d respectively. Sequence comparisons and phylogenetic tree analysis revealed that six of the patients harboured very similar strains and clustered together, including all incident and one prevalent case, which was implicated as index case. Further epidemiological analysis was consistent with patient to patient transmission. CONCLUSIONS: Molecular and epidemiological analysis suggested that horizontal nosocomial patient to patient transmission was the most likely explanation for the virus spread within the haemodialysis unit under study.

Prevalence and changes in hepatitis C virus genotypes among multitransfused persons with hemophilia. The Multicenter Hemophilia Cohort Study.

The purpose of this study was to determine hepatitis C virus (HCV) genotypes and their relationship to HCV RNA levels over time in a cohort of multitransfused hemophiliacs. Following reverse transcription and polymerase chain reaction amplification of HCV RNA, the product DNAs were genotyped by using the line probe assay. HCV RNA was quantified by the branched-chain DNA assay. Genotyping was done on 109 serum samples from 32 subjects. Genotype 3a had the highest prevalence (41%), followed by genotypes 1a (31%) and 1b (13%). Changes in genotypes were observed in 18 (58%) of the subjects >3-15 years of age. Changes were more common in human immunodeficiency virus (HIV)-positive subjects (13/17) than in HIV-negative subjects (5/15) (P=.014). HCV RNA increased 30-fold in HIV-positive subjects whose genotypes changed. Consensus nucleotide sequencing confirmed genotype changes in 2 patients. We conclude that genotype changes are common in hemophiliacs with chronic HCV, particularly in those who are coinfected with HIV.

Factors associated with severity and disease progression in chronic hepatitis C.

BACKGROUND/AIMS: Chronic hepatitis C appears to have a highly variable natural course with 20% of patients developing cirrhosis within 20 years, while the majority of them run a relatively mild course. We studied the relationships of epidemiological, biochemical and virological features with histological severity (grade) and liver disease progression (stage). METHODOLOGY: Liver histology, serum HCV RNA level and HCV genotype were determined in a well-defined cohort of 152 consecutive (100 males, 52 females) patients with chronic hepatitis C. RESULTS: Patients with minimal or mild chronic hepatitis were significantly younger than those with moderate or severe chronic hepatitis (mean age: 41.1 vs 49.5 years respectively, p=0.003). On the other hand, patients with no or mild fibrosis compared to those with moderate or severe fibrosis and to those with cirrhosis were significantly more frequently males (73%, 64% and 43%, p=0.01), parenteral drug users (36%, 11% and 11%, p=0.01) and infected with other than 1b genotype (86%, 52% and 33%, p<0.0001), significantly younger (mean age: 37, 48 and 58 years, p<0.0001) and had significantly lower HCV RNA levels (geometric mean: 6.9, 19.2 and 17.5 x 10(5) eq/ml, p=0.007). Multivariate analysis showed that stage was significantly related only to patient age (p<0.0001), HCV genotype (p=0.0025) and HCV RNA level (p=0.044). CONCLUSIONS: In chronic hepatitis C, histological severity seems to be associated only with patient age, while progression of the disease is mainly associated with patient age, HCV genotype and viremia level.

Prevalence patterns and genotypes of GB virus C/hepatitis G virus among imprisoned intravenous drug users.

An RT-PCR assay using primers from the 5'-UTR of the GBV-C/HGV genome was used to detect viremia, and a serological assay was used to detect past exposure to GBV-C/HGV, in sera from 106 imprisoned Greek intravenous drug users. High seroprevalence rates indicative of the parenteral route of transmission of the virus were found (32.1% for GBV-C RNA and 46.2% for anti-GBV-C E2). These rates were nonetheless lower in comparison to the corresponding rates of HCV infection markers (64.2% for HCV RNA and 77.4% for anti-HCV). Statistically significant univariate associations were observed between GBV-C-RNA positivity and younger age (P=0.006) and HCV-RNA positivity (P=0.024), as well as with higher serum alanine aminotransferase levels (P< 0.001); this latter association was shown to be independent of coinfection with HCV and of age by a multiple logistic regression model. Apparently, GBV-C/HGV had spread readily by needle-sharing in prison, while causing acute subclinical hepatitis in infected inmates. Phylogenetic analysis of the partial 5'-UTR of the GBV-C/HGV genome from 16 seropositive individuals, which delineated their grouping within genotype 2, also revealed a close genetic relationship between two sets of sequences from 4 drug addicts, 3 of whom admitted to sharing needles while imprisoned.

Immunologic events during the incubation period of hepatitis C virus infection: the role of antibodies to E2 glycoprotein. Multicentre Hemodialysis Cohort Study on Viral Hepatitis.

BACKGROUND: The study of the sensitivity of screening assays is greatly facilitated by testing the sequential changes in seroconverting individuals. The aim of this study was to investigate the early immunologic response after hepatitis C virus (HCV) infection and to evaluate whether HCV envelope (E2) recombinant antigen would provide a significant increase in sensitivity for detection of anti-HCV. STUDY DESIGN AND METHODS: Twenty hemodialysis patients who were seroconverting to anti-HCV were included in this study. They were followed up for a mean period (+/- SD) of 10.5 +/- 3.3 months, in which 13 to 46 serum samples per case were collected. Each sample was tested for anti-HCV by second- and third-generation enzyme immunoassay (EIA-2 and EIA-3) and recombinant immunoblot assay (RIBA-3). E2 antibodies were tested by a prototype EIA in which E2 was expressed as a recombinant antigen in Chinese hamster ovary cells. RESULTS: Alanine aminotransferase elevation was observed in 18 of 20 cases. Reactivity against c100, c33c, c22, NS5, and E2 was detected in 15 (75%), 19 (95%), 15 (75%), 2 (10%), and 17 (85%) patients, respectively; c33c was the most immunogenic antigen, followed in descending order by E2, c22, c100, and NS5. E2 antibody reactivity resolved the two RIBA-3-indeterminate cases. However, there was no case in which E2 reactivity preceded all other HCV antigens. Anti-E2 was found to react in all patients of genotypes 1a, 1b, and 3a but in only 2 of 4 patients of genotype 4a. CONCLUSION: In this group of seroconverting individuals, E2 antigen was shown to be highly immunoreactive and did resolve some RIBA-3-indeterminate samples as being positive, on the basis of reactivity to multiple antigens, but it did not improve early detection of seroconversion.

Significance of IgM anti-HCV core level in chronic hepatitis C.

AIM: To investigate the significance of IgM antibody to hepatitis C virus (HCV) core antigen (IgM anti-HCV core) in chronic hepatitis C. METHODS: In a group of 112 patients with histologically proven chronic hepatitis C positive for HCV RNA, IgM anti-HCV core level was studied by a sensitive semi-quantitative enzyme immunoassay. Quantitation of serum HCV RNA was done by a second generation bDNA assay and determination of HCV genotype by RT-PCR and reverse hybridization. RESULTS: IgM anti-HCV core was detected in 72 (64.3%) of the 112 patients. ALT levels were significantly higher in IgM anti-HCV core positive than negative patients. No other significant difference was observed in any of the patients' characteristics between IgM anti-HCV core positive and negative groups. On the contrary, IgM anti-HCV core level was found to be significantly higher in females than in males, in patients with moderate or severe chronic hepatitis, in patients with high HCV RNA levels and in patients infected with HCV genotype 1b. Moreover, IgM anti-HCV core level was significantly correlated with age and ALT level. Multiple regression analysis showed that IgM anti-HCV core level was significantly related only to the HCV genotype (p=0.001), histological grade (p=0.017) and ALT level (p=0.038). CONCLUSIONS: Our data support the hypothesis that IgM anti-HCV core level is associated mainly with HCV genotype and secondly with liver disease necroinflammatory activity. These associations may have implications in the pathogenesis of chronic hepatitis C.

Comparative efficacy of a high or low dose of interferon alpha 2b in chronic hepatitis C: a randomized controlled trial.

OBJECTIVES: Our objective was to determine the relative efficacy of 6 months of treatment with 10 MU versus 3 MU of interferon-alpha 2b (IFN-alpha), three times weekly, in chronic hepatitis C (HCV) in a randomized trial. METHODS: Ten megaunits of IFN-alpha were given to 28 patients (group A), and 3 MU were given to 30 patients (group B). After treatment ended, follow-up was continued for 26 wk. RESULTS: Overall, the sustained response rate was higher in group A than in group B (16/26 or 61.5% vs. 12/28 or 42.9%, p = 0.17), but the difference did not reach statistical significance. However, it was higher in group A than in group B among patients with minimal or mild chronic hepatitis (15/20 or 75% vs. 9/24 or 37.5%, p = 0.013) and among those with mild or moderate fibrosis (15/17 or 88.2% vs. 11/19 or 57.9%, p = 0.042). IFN-alpha treatment significantly reduced histological activity index (HAI) scoring and all its parameters, except fibrosis, but the decrease was similar in the two groups. Sex, age, stage, and HCV genotype were statistically significant predictors of sustained response in univariate analysis. However, multiple logistic regression analysis revealed that advanced histological stage (severe fibrosis and cirrhosis) was the only significant prognostic factor of poor sustained response (RR = 31.0, 95% CI 2-460, p = 0.01), whereas the presence of genotype 1 had marginal statistical significance (RR = 5.0, 95% CI 0.9-28, p = 0.07). CONCLUSIONS: 1) A larger dose of IFN-alpha does not improve the sustained response rate; however, it may be of benefit in early stages of chronic hepatitis C. 2) Pretreatment, histological stage, and possibly HCV genotype appear to be the main prognostic factors of sustained response.

Hepatitis C virus 1b is the dominant genotype in HCV-related carcinogenesis: a case-control study.

In an ongoing case-control study in Athens on the etiology of hepatocellular carcinoma (HCC), an analysis was made in order to assess whether HCV genotype 1b is associated with hepatocellular carcinoma (HCC). The HCV genotype was determined in 17 HCC patients, 87 patients with chronic hepatitis C (CHC) without cirrhosis (NC-CHC) and 23 patients with CHC and cirrhosis (C-CHC). HCV genotype 1b was detected in 14/17, 16/23 and 23/87 of HCC, C-CHC and NC-CHC respectively. The age- and gender-adjusted odds ratios contrasting HCC with NC-CHC and C-CHC with NC-CHC were 8.3 and 3.8 respectively. These data strongly support the hypothesis that HCV 1b is a stronger liver carcinogen than other HCV genotypes, probably through increased HCV replication and enhanced liver cytopathicity.

Biochemical and virological response of chronic hepatitis C after treatment with interferon-alpha for 6 or 12 months: predictors of sustained remission.

OBJECTIVE: To evaluate the biochemical and virological response in chronic hepatitis C patients treated with interferon-alpha at the usual dosage of 3 MU thrice weekly for 6 or 12 months, and to analyse the significance of clearance of serum HCV RNA and of HCV genotype in the prediction of sustained biochemical remission. SETTING: Liver Unit, Western Attica General Hospital, Athens, Greece. PARTICIPANTS: Sixty consecutive patients with histologically confirmed chronic hepatitis C. INTERVENTIONS: All patients received interferon-alpha-2b in a dose of 3 MU thrice weekly for 6 (n = 26) or 12 (n = 34) months. Serial serum samples were retrospectively tested for the presence of HCV RNA by a polymerase chain reaction assay and pretreatment serum samples for the determination of HCV genotype. RESULTS: Sustained biochemical response rate was significantly higher in the 12-month group (62% vs. 35%, P = 0.037). Clearance of serum HCV RNA at the end of treatment was achieved in 33 (58.9%) of the 56 patients with detectable pretreatment HCV RNA. HCV RNA reappeared in serum significantly more often in patients treated for 6 than for 12 months (35.7% vs. 5.3%, P = 0.037). Serum HCV RNA after 6 months of therapy was a prognostic factor of sustained biochemical response, which was observed in 75% of the HCV RNA-negative and in only 16.7% of the HCV RNA-positive patients (OR 0.067, P < 0.001). Moreover, in patients negative for HCV RNA after 6 months of therapy, 12 months' treatment resulted in a higher sustained response rate than did 6 months' (89% vs. 57%, P = 0.05). HCV genotype 1 was associated with a significantly lower sustained response rate (30% vs. 60.7%, P = 0.035), whereas 12 months' treatment induced sustained remission significantly more often only in patients with genotype 1 (6/12 vs. 0/8, P = 0.024). CONCLUSION: In chronic hepatitis C treatment HCV genotype and serum HCV RNA after 6 months of therapy are strong predictive factors of a sustained response, and a 12-month rather than a 6-month interferon regimen may induce a more persistent clearance of HCV RNA in total and a higher sustained response rate in patients with HCV genotype 1 and in those who clear HCV RNA after 6 months of therapy.