The hepatitis C virus (HCV) alternate reading frame protein or F protein of the HCV 1b genotype is a double-frameshift product of the HCV core protein. In order to assess the presence of antibodies specific for F protein and their clinical relevance in sera from HCV patients, we produced recombinant F protein and core protein of the HCV 1b genotype in Escherichia coli. An enzyme-linked immunosorbent assay was developed using purified recombinant HCV core, F protein, and a 99-residue synthetic F peptide (F99). The seroprevalences of anticore, anti-F protein, and anti-F99 synthetic peptide were 95%, 68%, and 36%, respectively, in 168 HCV patients. The prevalence of anti-F antibodies did not correlate with viral load, genotype, or alanine aminotransferase level. Interferon combination therapy induced a decline in the level of anti-F antibodies in 55 responders (P < 0.01). Thirteen responders (24%) lost their anti-F recombinant protein antibodies, and 17 (31%) lost their anti-F synthetic peptide antibodies, whereas no decrease was observed for the 17 nonresponders. These changes were significant between responders and nonresponders (P < 0.05). Meanwhile, no change was found in the anticore antibody titer of the 72 treated patients. The percentage of anti-F-protein-negative patients (15/15 [100%]) who achieved a sustained virological response (SVR) was higher than that of the anti-F-positive patients (70%) (P < 0.05). Based on these findings, HCV F protein elicits a specific antibody response other than the anticore protein response. Our data also suggest that the presence and level of anti-F antibody responses might be influenced by the treatment (interferon plus ribavirin) and associated with an SVR in Chinese hepatitis C patients.

This study demonstrated for the first time that the rs12979860 variation in IL28B could be a predictor of ETR and SVR in Chinese Han patients infected with HCV. The high frequency of the rs12979860 genotype CC might explain why the SVR rate is higher than that of the average global population.

The objective of this study was to find potential biomarkers for predicting sustained virologic responses to interferon-alpha (IFN-alpha) treatment in chronic hepatitis B (CHB) patients. A total of 101 CHB patients were treated with pegylated IFN-alpha2a for 48 weeks and followed up for 24 weeks, including 34 IFN responders (IFN-Rs) and 67 IFN nonresponders (IFN-NRs). After peripheral blood mononuclear cells (PBMCs) and Epstein-Barr virus-transferred B (EBV-B) cell lines were treated with different concentrations of IFN-alpha in vitro, activated IFN-stimulated gene factor3 (ISGF3) and IFN-gamma-activation factor (GAF) were measured by EMSA, and MxA, OAS1, and PKR mRNA were measured by real-time PCR. Polymorphisms in the MxA promoter were genotyped to find the possible association. IFN-alpha-activated ISGF3 and GAF levels were similar between IFN-NRs and IFN-Rs. However, MxA mRNA induction in IFN-Rs was higher than that in IFN-NRs, and such discrepancy increased when highly concentrated IFN was used to stimulate. The OAS1 and PKR mRNA induction have a similar pattern between IFN-Rs and IFN-NRs. In addition, frequency of the MxA-88G/T genotype was significantly different between IFN-Rs and IFN-NRs, and this polymorphism was also functional because MxA mRNA induction in patients with GG genotype was lower than those with GT genotype. Regression analysis showed that MxA mRNA induction after 10,000 IU/mL IFN stimulation could serve as an independent factor for predicting IFN-alpha, with an area under curve (AUC) of 0.838, a positive predictive value of 68% for IFN-Rs, and a negative predictive value of 89% for IFN-NRs. MxA mRNA induced by IFN-alpha might predict sustained virologic responses to IFN-alpha treatment in CHB patients.

The putative envelope protein E2 of hepatitis C virus (HCV) is the most variable antigenic fragment in the whole viral genome and is responsible mainly for the large inter- and intra-individual heterogeneity of the infecting virus. To analyze variation and immunogenicity of HCV envelope genes of HCV strains from China, the serum samples from 12 Chinese patients with chronic hepatitis C from 10 cities of China were amplified, sequenced directly, and compared with international strains reported previously. Variant analysis and immunogenicity prediction were then carried out with computer programs. The results suggested that HCV envelope genes show diversity in the north and the south of China and that they vary among different genotypes. Therefore, the diversity among different genotypes and derived areas should be calculated for HCV vaccine design; simultaneously, domains characterized by the hydrophilicity and the conserved immunogenicity could be targeted, for example, the domain of aa434-444, aa408-414, aa449-462 in the envelope region and aa399-406 in HVR1. These data may hold the key for future development of HCV vaccine in China.

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