Serological responses to infection with three different types of hepatitis C virus

Serological response to infection with different isolates of hepatitis C virus

Different isolates of hepatitis C virus (HCV) show nucleotide sequence variability throughout the genome. Detection of antibodies to recombinant proteins derived from hepatitis C virus genotype 1, the prototype HCV clone HCV-PT, constitutes the main method for screening HCV infection. The influence of the genomic variability on the serological diagnosis of HCV by enzyme immunoassay remains poorly defined. The aim of this study was to assess the serological reactivity of a panel of well characterized French HCV isolates typed by sequence analysis from patients with chronic hepatitis. The 73 sera samples were tested in three third generation EIA tests and three confirmatory assays. HCV isolates were determined by RT-PCR and sequencing in NS5B region of the genome. The 73 sera were positive in the three EIA tests. The three confirmatory tests showed a weaker reactivity with NS5 protein whatever the genotype, and a lower reactivity in NS4 antigens of non-type 1 sequences, particularly for genotype 3. Even though the reactivity of the antigens differed among the HCV isolates, the 73 isolates from genotype 1-6 were reactive with the three commercial screening assays. These results demonstrate that using a single test is adequate in the routine diagnosis of HCV infection in clinical laboratory, as recommended by the last French and European consensus conference.

The application of the bioelectric recognition assay for the detection of human and plant viruses: definition of operational parameters

The bioelectric recognition assay (BERA) is a novel biosensory method based on a unique combination of a group of cells, their immobilization in a matrix that preserves their physiological functions and the expression of the cell interaction with viruses as a change in electrical properties. A BERA sensor consists of an electroconductive, tube-like probe containing components of immobilized cells in a gel matrix. Cells are selected to specifically interact with the virus under detection. In this way, when a positive sample is added to the probe, a characteristic, 'signature-like' change in electrical potential occurs upon contact between the virus and the gel matrix. In the present study, we demonstrate that BERA can be used for the detection of viruses in humans (hepatitis C virus) and plants (tobacco and cucumber viruses) in a remarkably specific, rapid (1-2 min), reproducible and cost-efficient fashion. The sensitivity of the virus detection with BERA (0.1 ng) is equal or even better than with advanced immunological, cytological and molecular techniques, such as the reverse transcription polymerase chain reaction. Moreover, a good storability of the sensors can be achieved without affecting their performance. The potential use of portable BERA biosensors in medicine, for mass screening purposes, as well as for the detection of biological warfare agents without prior knowledge of a specific receptor-molecule interaction is discussed.

Bioelectric recognition assay (BERA)

A novel biosensory method has been developed for the determination of various chemical and biological molecules by assessing their electrophysiological interactions with a group of cells and cell components immobilized in a gel matrix that preserves their 'physiological' functions. The method was applied for the detection of: (i) hepatitis C virus in human blood samples; (ii) plant viruses; and (iii) a herbicide (glyphosate) in aqueous solutions. It was able to rapidly (assay time 3-5 min) and specifically detect the molecules in question at a concentration lower than 100 pg/ml, among other compounds f similar structure. The potential use of BERA biosensors for a rapid and cost-efficient molecule determination without prior knowledge of a specific receptor-molecule interaction is discussed.

Hepatitis C virus and interferon resistance

Interferon plays a critical role in the host's natural defense against viral infections and in their treatment. It is the only therapy for hepatitis C virus (HCV) infection; however, many virus isolates are resistant. Several HCV proteins have been shown to possess properties that enable the virus to evade the interferon-mediated cellular antiviral responses.

Antigenic heterogeneity of the hepatitis C virus NS4 protein as modeled with synthetic peptides

The effect of sequence heterogeneity on the immunologic properties of two strong antigenic regions of the hepatitis C virus (HCV) NS4 protein was studied by using a set of 443 overlapping 20-mer synthetic peptides. One antigenic region comprising the cleavage site between NS4a and NS4b (region 5-1-1) was modeled with peptides derived from 73 different known sequences, representing HCV genotypes 1-6. The other antigenic region, designated region 59 and located at the C-terminus of the NS4b protein, was modeled with peptides from 7 known sequences representing genotypes 1-3. All peptides were tested for antigenic reactivity by enzyme immunoassay with a panel of anti-HCV-positive serum specimens representing genotypes 1-5. The data demonstrated that immunoreactive peptides fell into two groups. One group, represented by N-terminal peptides, demonstrated genotype-independent immunoreactivity; the other group, from the central part of region 5-1-1, showed strict genotype specificity. Nineteen peptides from the genotype-independent group strongly immunoreacted with a wide range of serum samples containing antibodies to all 5 HCV genotypes. Twenty-five peptides from the genotype-specific group were found to strongly react with serum containing antibodies only to the genotype from which the peptides were derived. Similar to the N-terminal part of region 5-1-1, peptides derived from region 59 did not show genotype-specific immunoreactivity. Some peptides derived from the central part of region 59 showed very strong and broad antigenic reactivity. Thus, after examining two antigenic regions of the NS4 protein, we identified short sequences that can be used for the efficient detection of either genotype-independent or genotype-specific HCV antibodies.

Characterization of anti-hepatitis C virus-positive sera not genotyped by restriction fragment length polymorphism or serology

BACKGROUND

The hepatitis C virus genome is extremely heterogeneous and has been classified into six major genotypes. Genotyping of hepatitis C has been achieved through both direct molecular approach and indirect detection of host genotype-specific antibodies by serological methods. The purpose of this study was to characterize anti-hepatitis C positive sera samples that were not genotyped either by restriction fragment length polymorphism or by serology.

METHODS

Two hundred and two patients from northern California with established chronic hepatitis C virus infection were studied by restriction fragment length polymorphism analysis of the 5'-untranslated region amplicon. A serological genotyping assay, based on synthetic peptides derived from non-structural region 4 of the hepatitis C virus genome, was used to determine serological genotype.

RESULTS

Of the 202 patients studied, 187 (93%) were polymerase chain reaction-positive. One hundred and eighty-six patients were able to be genotyped by restriction fragment length polymorphism, compared with 144/202 (71%) of patients genotyped by serology (P < 0.0001). Only two of 202 samples showed discordant genotyping results. The distribution of hepatitis C virus genotypes in northern California was found to be type 1a, 41%; 1b, 35%; 2a, 3%; 2b, 10%; 3a, 11%; and 4, < 1%. There was no association between hepatitis C genotypes and age, gender distribution, ethnic origin, presumptive mode of transmission, serum alanine aminotransferase levels and the proportion of patients with cirrhosis. Of the 15 patients who were not genotypable by the molecular assay, four patients were genotyped by serology, with hepatitis C virus genotypes 1, 2 and 3 represented. Of the 58 samples that were not genotyped by serology, 47 were genotyped based on the molecular assay, and the distribution of hepatitis C virus genotypes was similar to that of the overall study population.

CONCLUSIONS

These data showed that: (i) molecular genotyping assay based on 5'-untranslated region is more sensitive than serologic genotyping based on the non-structural-4 region but the results were highly concordant; (ii) hepatitis C virus genotypes 1-4 are present in northern California, with genotype 1 being the most prevalent; and (iii) the failure to determine hepatitis C virus genotype based on molecular or serological genotyping assay does not appear to be related to specific hepatitis C genotypes.

Antigenic variation of core, NS3, and NS5 proteins among genotypes of hepatitis C virus

Assays that detect antibody to hepatitis C virus (HCV) are used to screen blood donors and patients with hepatitis. Current enzyme-linked immunosorbent assay (ELISA)-based methods are invariably based upon antigens from expressed recombinant proteins or oligopeptides from HCV type 1. Some HCV antigens used in screening assays are coded by regions of the HCV genome that show extensive variability; therefore, HCV type 1-based assays may be less effective for the detection of antibody elicited by infection with other genotypes. In this study, we have measured antibody reactivity of sera from 110 hepatitis C patients infected with type 1b, 3a, or 4a to genotype-specific and cross-reactive epitopes present in recombinant proteins from HCV genotypes 1b (core, NS3, and NS5), 3a (NS3, NS5), and 4a (core, NS3), corresponding to those used in current third-generation screening ELISAs. By comparing the serological reactivities of sera to type-homologous and type-heterologous antigens, we detected a significant type-specific component to the reactivity to NS3 (61 to 77% of the total reactivity) and NS5 (60% of the total reactivity). Furthermore, despite the similarities in the amino acid sequences of the core antigens of type 1b and type 4a, we also found significantly greater reactivity to type-homologous antigens, with approximately 25% of reactivity being type specific. These findings are consistent with previous findings of fivefold weaker reactivity of sera from HCV type 2- and HCV type 3-infected blood donors in the currently used third-generation ELISAs and suggest that these assays are suboptimal for screening populations in which the predominant genotype is not type 1.

Determination of HCV RNA concentration by direct quantitation of the products from a single RT-PCR

A novel method for the estimation of HCV RNA levels in vivo was developed, based on competitive RT-PCR. The use of the Tth DNA polymerase and 5' 32P-labeled antisense primer respectively reduced cross-contamination and permitted the direct quantification of viral loads by the analysis of the radioactivity of PCR products derived from a clinical sample and a competitive deleted template, separated previously on a polyacrilamide gel. A HCV fragment (H) and a competitive (deltaH) RNA templates were synthesized for optimizing the method. The minimal starting RNA detectable by RT-PCR was 40 copies. RT-PCR performed with ratios deltaH/H ranging from 1/1 to 1/20 revealed different relative percentages of both H and deltaH products, changing from 90% of deltaH product when the ratio was 1/1 to 5%, when it was 1/20. Regression analysis was adjusted to a linear model and served to further estimate HCV RNA loads from clinical samples. HCV RNA quantitation was carried out in 19 patients. Higher viral loads were related to type 1b infection and persistence of HCV RNA after interferon therapy. This method is simple, reproducible and useful for rapid estimation of HCV RNA load in vivo.

Typing of hepatitis C virus antibody with specific peptides in seropositive blood donors and comparison with genotyping of viral RNA

BACKGROUND AND OBJECTIVES

Serotyping of antibody to hepatitis C virus (anti-HCV) with specific peptides has been developed as an alternate method for typing HCV infections. The method does not require a prior amplification of viral RNA sequences from the sample. Identification of the viral genotype may be relevant for prognosis and clinical management.

MATERIALS AND METHODS

We used a previously described HCV serotyping assay (RIBA HCV Serotype SIA kit, Chiron Corp.) to investigate the serotype in 191 samples from blood donors selected for anti-HCV patterns (positive and indeterminate), ALT levels, and the presence or absence of viral RNA. The serotypes were compared with the genotypes obtained from typing the 5'-noncoding region of the viral RNA in 82 viremic samples.

RESULTS

We were able to obtain the viral serotype in 85% (114/134) of samples positive for anti-HCV but in only 3.5% (2/57) of the indeterminates. Lack of anti-NS4 in the sample was significantly associated with both untypable results and the presence of HCV serotypes other than serotype 1. The overall correlation with genotyping was 78% (64/82), rising to 95.5% (64/67) if only samples that could be both genotyped and serotyped were considered. The assay was easy to perform, gave reactivity patterns easy to interpret, and performed with high proficiency on anti-HCV-positive samples lacking detectable levels of viral RNA.

CONCLUSIONS

This is a practical and useful method for typing HCV infections in the clinical setting. The poor ability of the Core peptides to give the serotype in samples lacking anti-NS4 and the lack of specific peptides to recognize HCV types other than 1, 2, and 3 are, however, some aspects of the method that need improvement in the future.

Comparison of prevalence of anti-hepatitis C virus antibodies in differing South American populations

Very little is known about the distribution of hepatitis C virus (HCV) within South America. To assess the exposure of the general population to this virus, a number of sera obtained from three distinct geographical and racial groups were screened using a combination of immunoassays. Initial screening was undertaken with an inhouse immunoassay (core-ELISA) using synthetic peptides based on the N-terminus of the HCV core protein. Sera which were repeatedly positive by core-ELISA were also assessed using a commercial third-generation assay. The highest prevalence rate (2.3%) was seen in sera taken from the Tumaco region of Colombia. Lower rates were found in sera taken from La T, Ecuador (0.7%) and Las Majadas, Venezuela (0.7%). This indicates significantly different prevalence in different racial and geographical groups within the region.

Heterogeneity of hepatitis C virus

A great deal of information on the molecular heterogeneity of hepatitis C virus (HCV) has been achieved since its discovery in 1989. However, little is known about the clinical significance of these variations. Based on the degree of sequence variation, HCV has been classified into six major groups or types, differing by 31-34% at the nucleotide level over the entire virus genome. Each type is divided into several subtypes that differ by 20-23% in nucleotide sequence. Viruses within the same subtype are up to 10% divergent and, within infected individuals, vary by up to 1.5%. Genotype distributions are not homogeneous around the world and may reflect both historical and recent parenteral routes of transmission. The clinical implication of these genomic variations are not yet fully elucidated: genotype 1b has been associated with end-stage liver disease, including liver cirrhosis and hepatocellular carcinoma, but this finding might rather reflect its earlier introduction to the populations studied. Consistent evidence exists that types 2 and 3 have a higher response rate to interferon treatment than type 1, although the interplay between genotype and viral load in determining the response is still unclear. Immunohistochemical studies indicate a stronger activation of the endogenous interferon system in the liver of patients infected with type 1 compared to those infected with types 2 and 3, explaining, at least in part, its low responsiveness to exogenous interferon treatment. Biological, sequence-dependent variations of genotypes have been poorly investigated to date, but differential efficiency of translation activity of the 5' non-coding region has been reported. The availability of "in vitro" systems for evaluating pathogenetic aspects and neutralization mechanisms will improve the present knowledge on this world-wide infectious disease and on the clinical usefulness of distinguishing between genotypes.

Usefulness and limitation of phylogenetic analysis for hepatitis C virus core region: application to isolates from Egyptian and Yemeni patients

We report here the nucleotide sequences of the core region of HCV isolates from Egyptian and Yemeni patients and the method for classifying these HCV isolates by phylogenetic analysis. Sequence comparison suggested that the genotypes of these isolates were the same. Preliminary phylogenetic analysis of the HCV core region indicated that the genotypes of both isolates were 1c. However, an additional phylogenetic tree of the HCV core region constructed using a greater number of HCV isolates than that used in the preliminary analysis and on the basis of alignment of nucleotide sequences in an appropriate length indicated that the genotypes of these isolates were 4 and not 1c. For a more detailed analysis, the nucleotide sequences of the HCV E1 region as well as the core region for the same Yemeni patient were determined. A phylogenetic tree of the E1 region confirmed that the genotype of the HCV isolate from the Yemeni patient was 4. These data indicate that even when classifying HCV isolates using phylogenetic analysis, the misclassification would occur if care is not taken regarding the number and sequence lengths of the isolates included in the analysis.

Hepatitis C genotypes: current trends and future implications

OBJECTIVE

To review the geographic distribution and current understanding of hepatitis C virus (HCV) genotypes in regard to liver disease activity and response to treatment.

MATERIAL AND METHODS

We review the relevant medical literature and discuss our recent findings relative to chronic HCV infection and the importance of HCV genotypes.

RESULTS

HCV genotypes 1a and 1b are the most commonly found genotypes in patients with chronic HCV in the United States. Infection with HCV genotype 1b may be associated with more severe liver disease and may have a higher risk for the development of hepatocellular carcinoma. HCV genotype 2b seemed to be the most sensitive and HCV genotype 1b was the least sensitive to interferon therapy.

CONCLUSION

The identification of the infectious HCV genotype may be beneficial in clinical settings and may assist in the selection of patients who would benefit from interferon treatment.

Virology of hepatitis C virus

Hepatitis C virus (HCV) has been identified as the main causative agent of posttransfusion non-A, non-B hepatitis. Through recently developed diagnostic assays, routine serologic screening of blood donors has prevented most cases of posttransfusion hepatitis. The purpose of this paper is to comprehensively review current information regarding the virology of HCV. Recent findings on the genome organization, its relationship to other viruses, the replication of HCV ribonucleic acid, HCV translation, and HCV polyprotein expression and processing are discussed. Also reviewed are virus assembly and release, the variability of HCV and its classification into genotypes, the geographic distribution of HCV genotypes, and the biologic differences between HCV genotypes. The assays used in HCV genotyping are discussed in terms of reliability and consistency of results, and the molecular epidemiology of HCV infection is reviewed. These approaches to HCV epidemiology will prove valuable in documenting the spread of HCV in different risk groups, evaluating alternative (nonparenteral) routes of transmission, and in understanding more about the origins and evolution of HCV.

Evaluation of a reverse hybridization assay for genotyping of hepatitis C virus

BACKGROUND/AIMS

Several strains of the hepatitis C virus exist; distinct genotypes and subtypes can be identified by sequence comparison of the viral genomes. Recent evidence that the genotype/subtype of hepatitis C virus may influence the clinical course of chronic hepatitis C and the response to interferon-alpha therapy for this disease suggests that methods to identify the genotype may become clinically useful. In the present study we evaluated a recently introduced reverse hybridization assay.

METHODS

HCV-RNA was isolated from serum samples from 61 consecutive patients attending our out-patient clinic and subsequently sequenced in the 5'-noncoding and the nonstructural-5 region by the dideoxynucleotide chain termination method. HCV-genotyping was performed by phylogenetic analysis of nonstructural-5 sequences. The amplification product for the reverse hybridization assay was obtained by "nested" polymerase chain reaction using biotinylated primers corresponding to the 5'-noncoding region. The assay is based on hybridization of the resulting polymerase chain reaction product with oligonucleotide probes immobilized as parallel lines on membrane strips.

RESULTS

According to the phylogenetic analysis of the nonstructural-5 region the prevalence of hepatitis C virus subtypes was as follows: 1a 18%, 1b 51%, 2a 3%, 2b 3%, 2c 7% and 3a 18%. The reverse hybridization assay correctly identified each hepatitis C virus genotype (1, 2, and 3). However, differentiation of hepatitis C virus subtypes was insufficient. 1/11 HCV-1a isolates was incorrectly classified by the reverse hybridization assay as HCV-1b and vice versa 3/31 HCV-1b isolates as HCV-1a. Classification of hepatitis C virus subtypes 2a, 2b and 3a was correct, but 4/4 HCV-2c isolates were misinterpreted by the assay as HCV-2a.

CONCLUSIONS

The reverse hybridization assay can differentiate between hepatitis C virus genotypes 1, 2, and 3, but is not completely reliable for hepatitis C virus subtyping.

HCV genotypes in Swedish blood donors as correlated to epidemiology, liver disease and hepatitis C virus antibody profile

Sixty-two anti-HCV and HCV-RNA positive Swedish blood donors (44 men, 18 women; median age 34 years) were studied. HCV genotypes were correlated to parenteral risk factors, liver morphology, serum alanine aminotransferase (ALAT) levels and HCV antibody profile. Forty percent of the donors were infected with HCV genotype 1a, 10% with 1b, 21% with 2b, and 29% with 3a. Intravenous drug use (IVDU) was more common in donors with genotype 3a than in those with genotype 1a (p = 0.024), and prior blood transfusion more common in genotype 2b than in 3a (p = 0.012). Chronic active hepatitis with and without cirrhosis was found in 38% of donors infected with genotype 2b as compared to 8% of donors infected with 1a (p = 0.034). Forty percent of donors with genotype 1a had normal ALAT at the time of liver biopsy versus 11% with genotype 3a (p = 0.046). Antibodies to C33c and C22-3 were present in nearly all donors whereas reactivity to C100-3 and 5-1-1 was detected more often in donors with genotypes 1a and 1b as compared to donors with genotypes 2b and 3a. In conclusion, genotype 3a was correlated to IVDU or tattooing as parenteral risk factors for the acquisition of HCV infection, and genotype 2b to prior blood transfusion. Donors with genotypes 1a seemed to have less severe liver disease than those infected with genotypes 2b and 3a.

Genotyping of hepatitis C virus in South Africa

The six major hepatitis C virus genotypes were investigated by using samples from 79 seropositive and PCR-positive blood donors from three different regions of South Africa as well as 9 patients with chronic renal failure, 19 with liver disease, and 23 with hemophilia. PCR products of the genome were typed by restriction fragment length polymorphic analysis by RsaI-HaeIII and MvaI-HinfI double digestion. Type 5 occurred in 40% of this population group; type 1 occurred in 33%; and types 2, 3, and 4 were found in 13.8, 7.7, and 2.3%, respectively.

Genotype-dependent serologic reactivities in patients infected with hepatitis C virus in the United States

OBJECTIVE

To evaluate the serologic reactivities in patients infected with different hepatitis C virus (HCV) genotypes to four HCV proteins that are components of the second-generation recombinant immunoblot assay.

MATERIAL AND METHODS

Serum samples from 36 patients with chronic HCV infection were obtained. RNA was extracted by using chaotropic lysis and isopropanol precipitation. Reverse-transcriptase polymerase chain reaction of the NS-5 region was performed, followed by automated single-pass dideoxy sequencing of desalted amplification products. Classification of isolated HCV subtypes was based on Simmonds' system. All samples were tested for antibodies to proteins 5-1-1, C100-3, C33c, and C22-3 with the second-generation recombinant immunoblot assay.

RESULTS

Reactivity to protein 5-1-1 was significantly lower for patients with genotypes 2b and 3a than for those infected with HCV types 1a or 1b (P < 0.05). Antibody reactivity to the C100-3 protein was also reduced in patients infected with HCV types 2b and 3a.

CONCLUSION

These data indicate that the genotype-dependent differences in serologic reactivities are substantial among patients with chronic HCV infection.

Genotype distribution in Nagoya and new genotype (genotype 3a) in Japanese patients with hepatitis C virus

We evaluated hepatitis C virus (HCV) genotype distribution among Japanese patients in the city of Nagoya and the possible existence of any other genotype not determined by Okamoto's method. Eighty-five of 93 (91.4%) anti-HCV-positive patients had detectable HCV RNA. The genotype of the HCV isolate was determined in 84 of 85 (98.8%) of these HCV RNA-positive patients by Okamoto's method but determination was not possible in one (1.2%). Genotype 1b was detected in 58 of the 85 patients (68.2%), genotype 2a in 20 (23.5%), genotype 2b in 3 (3.5%), and genotype 1b + 2a in 3 (3.5%). In the remaining 1 patient in whom the genotype could not be determined, we determined the nucleotide sequence of the core region in HCV RNA extracted from this patient and evaluated it by molecular evolutionary analysis. This HCV isolate was then classified as genotype 3a. These results suggest that genotype 3a is rare among Japanese patients with HCV; thus, when classifying Japanese isolates, we should take more care because genotype 3a is not determined by current typing systems.

Serological reactivity and viral genotypes in hepatitis C virus infection

Patients infected with hepatitis C virus (HCV) were examined with four commercial HCV immunoblotting assays and for anti-GOR antibody to ascertain whether serological findings varied with the genotype of the infecting virus. The results indicate that patients infected with different HCV genotypes tend to show different immunoblotting profiles, mainly due to a low prevalence of antibodies to the viral region NS4 in patients infected with genotypes III and IV. Differences were more evident with second- than with third-generation assays. Patients infected with genotype IV exhibited a lower prevalence of anti-GOR antibody than patients infected with other genotypes.

Viral hepatitis. Current concepts for dental practice

The transmission of blood-borne viruses in the dental office is a potential hazard to patients and dental staff, particularly to oral and maxillofacial surgeons. Hepatitis B virus has been a recognized hazard for several years, and in the past oral surgeons and other dental health care staff have been infected as a result of occupational exposure. Hepatitis C virus in contrast does not appear to be a major occupational hazard to dental staff, nevertheless, infection with this virus can lead to significant morbidity and may have oral manifestations. Hepatitis D virus can be nosocomally transmitted, but vaccination against the hepatitis B virus minimizes this problem. Hepatitis E virus is not of clinical relevance to dentistry, although dental staff who are in areas of endemic infection can become infected as a result of enteric transmission. A number of other putative viral agents may also cause hepatitis, but additional data is awaited, and their significance to dental practice is unknown. This article summarizes current data on hepatitis viruses A, B, C, D, and E.

Hepatitis C virus and its genotypes in patients suffering from chronic hepatitis C with or without a cryoglobulinemia-related syndrome

Recently, evidence has been presented for a possible association between hepatitis C virus (HCV) infection and essential mixed cryoglobulinemia (EMC). Eleven consecutive patients with EMC and two with cryoglobulinemia type I were examined for the presence of markers of HCV infection. Eleven of 13 patients (10 with EMC and 1 with type I cryoglobulinemia) had anti-HCV antibodies (as determined by a second generation anti-HCV assay) and HCV-RNA in plasma or serum. HCV-RNA was also detected in liver biopsies of five patients. Genotyping showed that HCV genotype 1 was found in 10 of 11 patients with HCV-RNA (9 genotype 1b and 1 genotype 1a) and only one patient had HCV genotype 2. However, a similar high prevalence of genotype 1b (100%) was found in a group of 14 consecutive patients with chronic hepatitis C, who had no clinical evidence of cryoglobulinemia. Concomitant infection was present in three patients with genotypes 2, 3 and 4, respectively. These findings stress the high prevalence of HCV infection in patients with EMC and further study shows that a difference in genotype prevalence was not found between HCV-related EMC and chronic hepatitis C without clinical manifestations of EMC.

Genotype distribution of hepatitis C virus infection in Taiwan

To investigate the prevalence of genotype distribution of hepatitis C virus (HCV) infection in Taiwan, genotypes were identified in 122 (36 anti-HCV-positive blood donors, 44 anti-HCV-positive aborigines, 28 hemodialysis patients, and 14 patients with chronic liver diseases) of 280 subjects, using polymerase chain reaction by Okamoto's type-specific primer method. Type II was the dominant (66.7%) type among anti-HCV-positive blood donors, followed by type III and type IV with the same percentages (16.7%), while none of type I was detected. The prevalence of genotype distribution were 75.0%, 81.1%, and 64.3% for type II, 4.6%, 17.9%, and 21.4% for type III, 13.6%, 0%, and 7.1% for type IV, for the aborigines, hemodialysis, and chronic liver diseases groups, respectively. Four subjects revealed mixed infections by two different genotypes: two cases of II and III; and each one case of II and IV, and III and IV. Diverse genotype distributions in two hemodialysis groups disclose the existence of obvious regional differences even within a region. The results reveal the highest prevalence of type II as in Japan. However, there is a higher prevalence rate of type IV than in Japan.

Sequence variability of hepatitis C virus and its clinical relevance

Chronic type C hepatitis is a potentially serious disease that can lead to cirrhosis and hepatocellular carcinoma. This complex disease is caused by the hepatitis C virus (HCV), a positive sense, single-stranded RNA virus. HCV has been assigned to a separate genus within the Flaviviridae, and shares a close relationship to the pestiviruses. Nucleotide sequence variation has been observed in genomes amplified from serum of patients with HCV infection, and cloning of RNA amplified from patients infected with HCV has confirmed the heterogeneity of the agent responsible for post-transfusion and sporadic hepatitis C. The variability of HCV is structured in a way that immediately suggests a two tiered classification: this nomenclature comprises 'types' corresponding to the major branches in a phylogenetic tree of sequences from genomic or subgenomic regions of the genome, and 'subtypes', corresponding to the more closely related sequences within some of the major groups. This genotyping designation has provided an epidemiological tool for studying geographical differences in hepatitis C infection. Clearly discernible patterns of genotype distribution have been found in those countries that have been studied so far. In many European countries genotype distributions vary with the age of patients, reflecting rapid changes in genotype distribution with time within a single geographical area. Unfortunately we know very little about modes of transmission within different communities. There is considerable interest in the clinical significance of different HCV genotypes, and the intriguing question of whether these differences may affect the spectrum of the disease associated with hepatitis C. These data also have implications for diagnosis and treatment of acute and chronic hepatitis C. A uniform typing scheme and nomenclature will facilitate our understanding of the disease caused by this virus worldwide.

Immune responses of blood donors to peptides of various lengths and those with genotypic sequence variations corresponding to the N-terminal portion of the core protein of hepatitis C virus

Immune reactivities of blood donor sera with the peptides of various lengths (24, 30, 40 and 50 mer) and those with genotypic sequence variations in the N-terminal portion of the core protein of hepatitis C virus (HCV) were compared by enzyme-linked immunosorbent assays. It was found that a 40-mer oligopeptide (amino acids 2-41) was recognized more frequently than other peptides even in serum samples that did not react with the C22-3 (core) by the recombinant immunoblot assay (RIBA-II). On the other hand, a 30-mer peptide (amino acids 1-30) had good correlation with viremia as confirmed by the polymerase chain reaction (PCR). In addition, four individuals showed the obvious differences in the immune responses to 30-mer oligopeptides representing the 4 genotypic variations. As a result, some samples that were PCR-positive but nonreactive by a commercial assay were found to react with short synthetic peptides in the N-terminal portion of the core protein.

Factors predictive of the response to interferon in patients with chronic hepatitis C

Factors predictive of the response to interferon in patients with chronic hepatitis C remain to be identified. In this study, we investigated factors predictive of the short-term response, defined as a return to normal alanine aminotransferase activity after treatment, and the long-term response defined as normal alanine aminotransferase activity 1 year after completing treatment, in 75 patients with chronic hepatitis C virus treated with recombinant alpha interferon (either 6 MU x 3/week for 3 months then 3 MU x 3/week for 3 months (n = 27) or 3 MU x 3/week for 6 months (n = 48)). At the end of treatment, 42 patients (56%) had normal alanine aminotransferase activity ("responders") and 33 (44%) had high alanine aminotransferase activity ("non-responders"). Twenty (48%) of the 42 responders had normal alanine aminotransferase activity 1 year after treatment ("sustained responders"), while 22 (52%) had high alanine aminotransferase activity ("transient responders"). The dosage of interferon was not predictive of the short-term and the long-term response to treatment. The responders differed significantly from the non-responders in terms of age, i.v. drug abuse, aspartate aminotransferase, gammaglutamyltranspeptidase and alkaline phosphatase activities, bilirubinemia, serum bile acid concentrations, prothrombin time, platelet count, ferritinemia, hyaluronic acid levels, positivity for the antibody to 5.1.1 of the recombinant immunoblot assay band and the histological fibrosis score. The following parameters were independently correlated with the short-term response in a multivariate analysis: gammaglutamyltranspeptidase activity, serum bile acid concentrations and positivity for the antibody to 5.1.1 of the recombinant immunoblot assay band.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of hepatitis C virus genotypes by a line probe assay and correlation with antibody profiles

The 5' untranslated regions derived from 54 patients with a chronic hepatitis C virus infection were analyzed to determine the (sub)type of hepatitis C virus. Labelled polymerase chain reaction products from 5' untranslated region were used as probes for reverse hybridization in a line probe assay (Inno-LiPA) and results were validated by comparison with direct sequencing data. Five different genotypes could be distinguished based on 5' untranslated region sequence diversity. Results of typing by line probe assay and direct sequencing were similar. Antibody responses against core, NS-3, NS-4 and NS-5 epitopes were detected by RIBA-4 and Inno-LIA HCVAb II confirmatory assays. There was no consistent correlation between genotype and anti-HCV responses, although types 2, 3 and 4 hepatitis C virus isolates show poor reactivity with NS-4 ep!%"pes.

Hepatitis C virus genotypes, reactivity to recombinant immunoblot assay 2 antigens and liver disease

To clarify the relationship between hepatitis C virus (HCV) genotypes and liver disease, we typed HCV genomes in the sera of 151 blood donors, 180 patients with type C chronic liver disease (CLD), and 30 haemophiliacs residing in Hiroshima, Japan. All of the subjects were positive for anti-HCV and HCV-RNA, and were examined for seroreactivity to HCV-specific antigens. The HCV genotypes were determined by polymerase chain reaction (PCR) with type-specific primers deduced from the putative core region of the HCV genome. Significantly more (P < 0.001) type III HCV was found in the samples from the CLD patients (80%) than in those from the blood donors (55%). Significantly more (P < 0.001) type III HCV was found in the samples from the blood donors (29.1%) than in those from the CLD patients (11.7%). There was no significant difference in the distribution of the HCV types among the patients with chronic active hepatitis, liver cirrhosis, and hepatocellular carcinoma. A four-antigen recombinant immunoblot assay (RIBA-2) assay was used to compare the serum samples for their reactivity to a range of structural and nonstructural peptides specific for HCV (5-1-1, C100-3, C33c, and C22-3). The frequency of seropositivity to 5-1-1 and C100-3 was significantly higher (P < 0.001) in type II HCV-infected blood donors than in type III HCV-infected donors (68.2% and 65.9% vs. 4.5% and 22.7%, respectively). Among the type III HCV-infected individuals, the CLD patients had a significantly higher (P < 0.01) frequency of seropositivity to 5-1-1 than the blood donors (33.3% vs. 4.5%).(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical significance of hepatitis C antibodies in blood donors

The clinical significance of hepatitis C antibodies (anti-HCV) in a healthy population was studied by liver function tests and liver biopsies. The patient population consisted of 195 (96.1%) of the 203 blood donors found to be either anti-HCV positive or indeterminate by a recombinant immunoblot assay (RIBA) during the first year of anti-HCV screening of 307,606 donors in Finland using a first generation enzyme-linked immunosorbent assay. Alanine aminotransferase (ALT) levels in 67 donors reacting positively and in 128 reacting indeterminately by a second generation RIBA (RIBA-4) were monitored to evaluate the prevalence of liver damage. Serum N-terminal type III procollagen (PIIINP) concentrations were measured in all donors who fulfilled our criterion for possible hepatitis C (ALT values over two times the normal upper limit on two occasions or over five times the normal upper limit on one occasion) and in 23 randomly selected RIBA-4 positive donors without ALT abnormalities (control group). Two (1.6%) of the RIBA-4 indeterminate donors had ALT values compatible with possible hepatitis C (negative by polymerase chain reaction) whereas there were 25 (37.3%) such individuals among the RIBA-4 positive donors (P < 0.0005). Twenty (80%) of the latter 25 RIBA-4 positive donors with possible hepatitis C consented to liver biopsy. Of these 20 donors, 11 (55.0%) were found to have chronic persistent hepatitis, four (20.0%) mild, three (15.0%) moderate, and two (10.0%) severe chronic active hepatitis.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies and viremia in acute post-transfusion hepatitis C: a prospective study

Fourteen patients who developed acute post-transfusion hepatitis C after open-heart surgery were studied for seroconversion, viremia, and aminotransferase. Anti-HCV antibodies were measured by first and second generation ELISA and became positive between one week and more than 6 months after infection. Seroconversion in four patients and passively transfused antibodies were only found by the second generation assay, indicating its significantly higher sensitivity. Viremia was detected by reverse transcription and the polymerase chain reaction within the first 4 weeks of infection in 13 patients and persisted for more than 2 years in all of them. One patient died of cardiac cause. Viral strains were heterogeneous between the different patients, but showed no significant variation within one patient during the course of hepatitis deduced from the results with different sets of oligonucleotides. Viremia preceded hepatitis by 4 weeks, seroconversion determined by ELISA II followed after an 8 week interval, and anti-C-100 antibodies appeared 26 weeks later. Aminotransferase activities returned to normal values in 10 patients.

Geographical distribution of hepatitis C virus genotypes in blood donors: an international collaborative survey

The frequency of infection with the six classified major genotypes of hepatitis C virus (HCV) was investigated in 447 infected volunteer blood donors from the following nine countries: Scotland, Finland, The Netherlands, Hungary, Australia, Egypt, Japan, Hong Kong, and Taiwan. Viral sequences in plasma from blood donors infected with HCV were amplified in the 5'-noncoding region and were typed by restriction fragment length polymorphism analysis. Electrophoresis of DNA fragments produced by cleavage with HaeIII-RsaI and ScrFI-HinfI allowed HCV types 1 (or 5), 2, 3, 4, and 6 to be identified. Further analysis with MvaI-HinfI allowed sequences of the type 5 genotype to be distinguished from sequences of the type 1 genotype. Types 1, 2, and 3 accounted for almost all infections in donors from Scotland, Finland, The Netherlands, and Australia. Types 2 and 3 were not found in the eastern European country (Hungary), where all but one of the donors were infected with type 1. Donors from Japan and Taiwan were infected only with type 1 or 2, while types 1, 2, and 6 were found in those from Hong Kong. HCV infection among Egyptians was almost always by type 4. Donors infected with HCV type 1 showed broad serological reactivity with all four antigens of the second generation Chiron RIBA-2 assay (Chiron Corporation, Emeryville, Calif.), while infection with divergent HCV genotypes elicited antibodies mainly reactive to c22-3 and c33c. Reactivities with antibodies 5-1-1 and c100-3 were infrequent and were generally weak, irrespective of the geographical origin of the donor. Because the envelope region of HCV is even more variable than the NS-4 region, it is likely that vaccines based on these proteins need to be multivalent and perhaps specifically adapted for different geographical regions.

New genotype of hepatitis C virus in South Africa

Partial nucleotide sequences in the core region of the hepatitis C viral genome were determined by reverse transcription followed by polymerase chain reaction, in a patient with chronic hepatitis from South Africa. These nucleotide sequences showed a low degree of homology with known types of HCV: the degree of homology between the nucleotide sequences of these clones with HC-J1, J4, J6, J7, Tr, and Eb-1 were 86.1-87.3%, 87.3-87.9%, 83.0-83.9%, 81.1-82.0%, 81.0-82.2%, and 82.8-83.4%, respectively, and that the deduced amino acid sequence homologies between these clones and HC-J1, J4, H6, J7, Tr, and Eb-1 were 90.7-91.6%, 89.7-91.6%, 91.6-93.5%, 90.7-91.6%, 81.5-82.4%, and 89.2-90.2%, respectively. The nucleotide sequence homologies of these clones with HC-J1, J4, J6, J7, Tr, and Eb-1 were very low, compared to those between the same genotype. Further comparison using molecular evolutionary methods suggested that this sequences should be classified in a new genotype.

Rolling review--the pathogenesis, diagnosis and management of viral hepatitis

Five major hepatotrophic viruses have been identified. The pathogenesis, diagnosis and treatment of chronic viral hepatitis continues to be intensely researched. Experimental evidence suggests that HLA restricted virus-specific T cells play a role in hepatocellular injury in type A hepatitis. The absence of chronic infection indicates the effectiveness of the host immune response to hepatitis A virus (HAV). It is postulated that HAV may rarely trigger an autoimmune chronic hepatitis. Active prophylaxis of hepatitis A is possible. The elimination of hepatitis B is dependent on the recognition of viral determinants in association with HLA proteins on infected hepatocytes by cytotoxic T cells. The specific epitopes recognized by B and T cells are being mapped. Polymerase chain reaction (PCR) amplification and sequencing of genomic DNA in patients with chronic hepatitis B has indicated that nucleotide substitutions in the genome are not uncommon. Their pathogenicity is being explored. Antiviral therapy for hepatitis B remains difficult. Interferon is effective in a proportion of patients. Thymosin may prove to be more effective immunomodulatory therapy. New nucleoside analogues suppress HBV replication, but the safety of these drugs has been questioned after the appearance of severe liver toxicity with fialuridine. The data that hepatitis D virus is pathogenic has recently been challenged with the observation that HDV re-occurs in transplanted liver after engrafting, but without signs of HBV recurrence or evidence of liver damage. Treatment of hepatitis D virus remains difficult. Several isolates of hepatitis C virus have been cloned, and the sequence divergence of these isolates indicates that there are several major genotypes and component subtypes of this polymorphic virus.(ABSTRACT TRUNCATED AT 250 WORDS)

Hepatitis C virus serological and polymerase chain reactions in human immunodeficiency virus-positive and -negative patients

BACKGROUND

Polytransfused patients may be dually infected with hepatitis C virus (HCV) and human immunodeficiency virus (HIV).

OBJECTIVES

To assess the correlation of antibodies to HCV with viral RNA in serum as determined by polymerase chain reaction (PCR) in anti HIV-positive and -negative haemophiliacs.

STUDY DESIGN

Serum from 150 Patients with or without HIV infection were examined for anti-HCV by second generation enzyme-linked immunosorbent assay (ELISA) and recombinant immunoblotting assay (RIBA). A sample was also tested in a nested-reverse transcription PCR for a conserved sequence of the 5' untranslated region of HCV. PCR-positive specimens were titrated and a type-specific PCR using viral core gene sequences was used to determine distribution of HCV viral types.

RESULTS

Eighty-seven percent of the patients were positive in ELISA. All the positives but 2 were either positive of indeterminate in RIBA. The frequency of indeterminate RIBA results was 33% among HIV-positive subjects and less than 1% among HIV-negative ones. PCR was positive in 68% of 73 RIBA-positive or -indeterminate individuals and negative in all HCV-seronegative individuals examined. No significant differences were observed in HCV viral type, prevalence or titers of viraemia between HIV-positive or -negative patients.

CONCLUSIONS

The majority (68%) of anti-HCV-positive haemophiliacs examined in this study had HCV RNA in their sera and anti-HCV profile determined by RIBA had no apparent influence on viraemia. The presence of HIV infection in these patients had no significant impact on HCV RNA prevalence, titer or HCV type distribution.

Prevalence of antibody to hepatitis C virus (HCV) in HIV-1-infected patients (nice SEROCO cohort)

The prevalence of antibody to hepatitis C virus (HCV) in a cohort of 272 HIV-infected patients was assessed by means of 4 anti-HCV assays: a 1st generation and a neutralization test, a 2nd generation test, and a confirmatory test, the dot-blot Matrix HCV immunoassay. The cohort included, as a single risk factor, 35.7% intravenous drug users (IVDUs), 25% homosexual men, 30.1% heterosexual individuals, 5.9% transfused patients, 0.7% occupational infections, and 2.6% patients with unknown infection source, and was studied on entry and in samples collected for up to 36 months. Results showed that on entry (i) sera of 83 out of 272 members of the cohort were positive by the HCV 1st generation EIA (30.5%); 70 were confirmed by the neutralization test (84.3%); (ii) 115 of the cohort were reactive with the 2nd generation HCV EIA (41.3%); (iii) with the dot-blot immunoassay 99 (86.1%) of the cohort were confirmed and 16 remained indeterminate. The overall confirmed HCV antibody-positive rate in these 272 patients was 36.4%. Antibody to HCV was detected in 78.3% of IVDUs, 18.3% of heterosexual individuals, 31.2% of transfused patients, and only 2.9% of homosexual men. The 36-month follow-up of this cohort revealed that 4/145 patients became anti-HCV positive by second generation assay. Hepatitis B markers were frequently associated with HCV in IVDUs (71.1%) but infrequently in heterosexual (8.5%) or homosexual (1.5%) individuals. Our results suggest that HCV 2nd generation EIA used in combination with the semiautomated dot-blot assay as a confirmatory test improves the specificity and sensitivity for HCV antibody detection.(ABSTRACT TRUNCATED AT 250 WORDS)

Low risk of sexual transmission of hepatitis C virus in Somalia

The prevalence in Somalia of antibody to hepatitis C virus (anti-HCV) was determined in a survey of 236 female prostitutes, 80 sexually transmitted disease (STD) clinic patients, 79 male soldiers, and 43 tuberculosis patients. Of 98 (22%) serum samples repeatedly anti-HCV reactive by first and second generation enzyme-linked immunosorbent assay kits, only 8 (1.8%) were anti-HCV positive by immunoblot assay (RIBA-2). Anti-HCV seropositivity by immunoblot assay was not associated with any risk group or with positive syphilis serology (found in 18% of subjects) or antibody to human immunodeficiency virus 1 (in 1.4% of subjects). These data indicate that sexual transmission of hepatitis C virus is not common in Somalia among sexually active populations, including female prostitutes and other groups at high risk of STDs and the acquired immune deficiency syndrome.