Anders Widell

Consensus proposals for a unified system of nomenclature of hepatitis C virus genotypes

International standardization and coordination of the nomenclature of variants of hepatitis C virus (HCV) is increasingly needed as more is discovered about the scale of HCV‐related liver disease and important biological and antigenic differences that exist between variants. A group of scientists expert in the field of HCV genetic variability, and those involved in development of HCV sequence databases, the Hepatitis Virus Database (Japan), euHCVdb (France), and Los Alamos (United States), met to re‐examine the status of HCV genotype nomenclature, resolve conflicting genotype or subtype names among described variants of HCV, and draw up revised criteria for the assignment of new genotypes as they are discovered in the future. A comprehensive listing of all currently classified variants of HCV incorporates a number of agreed genotype and subtype name reassignments to create consistency in nomenclature. The paper also contains consensus proposals for the classification of new variants into genotypes and subtypes, which recognizes and incorporates new knowledge of HCV genetic diversity and epidemiology. A proposal was made that HCV variants be classified into 6 genotypes (representing the 6 genetic groups defined by phylogenetic analysis). Subtype name assignment will be either confirmed or provisional, depending on the availability of complete or partial nucleotide sequence data, or remain unassigned where fewer than 3 examples of a new subtype have been described. In conclusion, these proposals provide the framework by which the HCV databases store and provide access to data on HCV, which will internationally coordinate the assignment of new genotypes and subtypes in the future. (HEPATOLOGY 2005.)

Topology of the Membrane-Associated Hepatitis C Virus Protein NS4B

ABSTRACT Hepatitis C virus (HCV) belongs to the Hepacivirus genus in the Flaviviridae family. Among the least known viral proteins in this family is the nonstructural protein NS4B, which has been suggested to be a part of the replication complex. Hydrophobicity plots indicate a common profile among the NS4B proteins from different members of the Flaviviridae family, suggesting a common function. In order to gain a deeper understanding of the nature of HCV NS4B, we have determined localization and topology of this protein by using recombinant HCV NS4B constructs. The protein localized to the endoplasmic reticulum (ER), but also induced a pattern of cytoplasmic foci positive for markers of the ER. Computer predictions of the membrane topology of NS4B suggested that it has four transmembrane segments. The N and C termini were anticipated to be localized in the cytoplasm, because they are processed by the cytoplasmic NS3 protein. By introducing glycosylation sites at various positions in HCV NS4B, we show that the C terminus is cytoplasmic and the loop around residue 161 is lumenal as predicted. Surprisingly, the N-terminal tail was translocated into the lumen in a considerable fraction of the NS4B molecules, most likely by a posttranslational process. Interestingly, NS4B proteins of the yellow fever and dengue viruses also have their N termini located in the ER lumen due to an N-terminal signal peptide not found in NS4B of HCV. A shared topology achieved in two different ways supports the notion of a common function for NS4B in Flaviviridae.

Prevalence studies of GB virus-C infection using reverse transcriptase-polymerase chain reaction

Among the three recently described GB viruses (GBV‐A, GBV‐B, and GBV‐C), only GBV‐C has been linked to cryptogenic hepatitis in man. Because of the limited utility of currently available research tests to determine antibody response to GBV‐C proteins, the prevalence of GBV‐C RNA in human sera was studied using reverse transcription‐polymerase chain reaction (RT‐PCR). The prevalence of GBV‐C is higher among volunteer blood donors with elevated serum alanine aminotransferase (ALT) levels (3.9%) than among volunteer blood donors with normal ALT levels (0.8%). Higher rates were also noted among commercial blood donors (12.9%) and intravenous drug users (16.0%). GBV‐C was frequently detected in residents of West Africa, where the prevalence was >10% in most age groups. Approximately 20% of patients diagnosed with either acute or chronic hepatitis C virus (HCV) were found to be positive for GBV‐C RNA. In addition, GBV‐C RNA sequences were detected in individuals diagnosed with non‐A‐E hepatitis, with clinical courses ranging from mild disease to fulminant hepatitis. Fourteen of sixteen subjects with or without clinically apparent hepatitis were positive for GBV‐C RNA more than 1 year after the initial positive result.

Mother-to-infant transmission of hepatitis C virus

OBJECTIVE To describe the rate of perinatal transmission of hepatitis C virus (HCV). DESIGN Follow-up study of newborn children of mothers with chronic HCV infection. SETTING A university hospital in Sweden. PARTICIPANTS Fourteen women with chronic HCV infection and their 21 newly born children. MAIN OUTCOME MEASURES Detection of HCV RNA in serum by the polymerase chain reaction and detection of anti-HCV antibody by second generation assays. RESULTS All mothers were found to be positive for anti-HCV antibody both by second-generation enzyme-linked immunosorbent assay (ELISA) and by second-generation recombinant immunoblot assay (RIBA-2); all also had detectable serum HCV RNA. Two children had long-lasting alanine aminotransferase (ALT) elevations, and one of them became HCV RNA positive. None of the other children developed biochemical hepatitis. However, two additional children had temporary viremia. Only the child with biochemical and biopsy-proven hepatitis and detectable HCV RNA in multiple blood samples actively produced anti-HCV antibody. CONCLUSIONS Mother-to-infant transmission of HCV infection from chronically infected women without human immunodeficiency virus (HIV) infection seems to be uncommon.

Typing of hepatitis C virus isolates by DNA enzyme immunoassay

Recently, at least six types of hepatitis C viruses (HCV) have been identified. Different types of HCV appear to possess different pathogenic properties and a different sensitivity to interferon treatment. Typing of HCV isolates may therefore be an important diagnostic procedure. We report on a new method for identification of HCV types 1a, 1b, 2a, 2b and 3a which are most prevalent in Europe, North America and Japan. The assay is based on a combination of two well established techniques, the polymerase chain reaction (PCR) and DNA enzyme immunoassay (DEIA). In the first step of the method a cDNA of about 250 bp corresponding to the HCV core-region is amplified by nested PCR. The target cDNA is then hybridized to type-specific oligonucleotides fixed to a solid phase through an avidin-biotin bridge. The formed hybrids are detected by a standard ELISA using monoclonal antibodies reacting with double-stranded DNA. Typically, signal-to-noise (S/N) ratios between 18.2 and 48.6 could be observed when different HCV types/subtypes were analyzed by this method. The test was evaluated using cloned HCV cDNAs of known types and by sequence determination of some of the typed cDNAs. Typing of 115 isolates from Germany, Russia and Turkey revealed that subtype 1b (59-100%) and 1a (24-32%) are most prevalent in these countries.

Hepatitis C superinfection in hepatitis C virus (HCV)-infected patients transplanted with an HCV-infected kidney

Hepatitis C virus (HCV) genotypes, determined by polymerase chain reaction with type-specific primers, were studied in 5 already HCV-infected patients receiving kidneys from HCV-infected cadaver donors. Three patients were investigated retrospectively using stored pre- and posttransplantation sera and followed 18-28 months after transplantation. Two recipients with HCV genotype 2b infection had received kidneys from 1 genotype 3a-infected donor. In 1 recipient, HCV 2b was replaced by the donors type; in the other recipient, a prolonged mixed infection of 3a and 2b occurred. Persistent alanine aminotransferase (ALT) elevation (3- to 5-fold) appeared in both patients. The third patient, also HCV 2b infected when transplanted with an HCV 3a-infected kidney, remained infected with HCV 2b only. Two patients, one with HCV genotype 1b and the other with genotype 3a, were followed prospectively with frequent bleeds (initially biweekly) and genotyping over 14 months after they had received kidneys from 1 HCV genotype 1a-infected donor. The HCV 1b-infected recipient remained infected with 1b only and had minimal biochemical signs of liver injury. In the other recipient, mixed infection of 3a and 1a appeared at week 3 and persisted for several weeks, until only genotype 1a could be detected. This patient had elevated ALT levels before transplantation. After onset of mixed infection, ALT levels increased further for several weeks, and returned to pretransplantation levels when only HCV 1a was found. HCV-infected kidneys transplanted into HCV-infected recipients gave 3 different virus patterns. Most patients benefitted in the short term, but some super-infected patients experienced increased liver damage.

Recombinant human monoclonal antibodies against different conformational epitopes of the E2 envelope glycoprotein of hepatitis C virus that inhibit its interaction with CD81.

The antibody response to the envelope proteins of hepatitis C virus (HCV) may play an important role in controlling the infection. To allow molecular analyses of protective antibodies, we isolated human monoclonal antibodies to the E2 envelope glycoprotein of HCV from a combinatorial Fab library established from bone marrow of a chronically HCV-infected patient. Anti-E2 reactive clones were selected using recombinant E2 protein. The bone marrow donor carried HCV genotype 2b, and E2 used for selection was of genotype 1a. The antibody clones were expressed as Fab fragments in E. coli, and as Fab fragments and IgG1 in CHO cells. Seven different antibody clones were characterized, and shown to have high affinity for E2, genotype 1a. Three clones also had high affinity for E2 of genotype 1b. They all bind to conformation-dependent epitopes. Five clones compete for the same or overlapping binding sites, while two bind to one or two other epitopes of E2. Four clones corresponding to the different epitopes were tested as purified IgG1 for blocking the CD81-E2 interaction in vitro; all four were positive at 0.3-0.5 microg/ml. Thus, the present results suggest the existence of at least two conserved epitopes in E2 that mediate inhibition of the E2-CD81 interaction, of which one appeared immunodominant in this donor.

Continued transmission of hepatitis B and C viruses, but no transmission of human immunodeficiency virus among intravenous drug users participating in a syringe/needle exchange program.

The virological efficacy of a syringe/needle exchange program was evaluated in a cohort incidence study. Of 698 intravenous drug users (IVDUs) initially recruited, 15 (2.1%) were HIV-positive at baseline. Adequate follow-up was possible in 515 (74%) and showed no new cases of HIV infection during a median of 31 months. Most IVDUs had been previously exposed to HBV (anti-HBc-positive 70.1%) and HCV (anti-HCV-positive 90.7%). Of those 159 IVDUs negative at baseline for anti-HBc and/or anti-HCV, 56 (35%) seroconverted to one or both viruses during follow-up, corresponding to 11.7 seroconversions/100 y at risk for HBV and 26.3 seroconversions/100 y for HCV. Multiple logistic regression analysis showed hepatitis seroconversion to correlate with imprisonment during the study (OR 2.2; 95% CI 1.04-4.74), absence of drug-free periods (OR 5.7; CI 1.44-22.3) and frequent syringe/needle exchanges (OR 1.31; CI 1.02-1.7). The absence of HIV spread was probably partly due to the low prevalence of HIV-infected IVDUs in the city. Despite free syringes and needles, both HBV and HCV continued to spread at high rates. Nevertheless, syringe/needle exchange programs, coupled with monitoring of serostatus provide good surveillance and are valuable for further assessment of remaining risks.The virological efficacy of a syringe/needle exchange program was evaluated in a cohort incidence study. Of 698 intravenous drug users (IVDUs) initially recruited, 15 (2.1%) were HIV-positive at baseline. Adequate follow-up was possible in 515 (74%) and showed no new cases of HIV infection during a median of 31 months. Most IVDUs had been previously exposed to HBV (anti-HBc-positive 70.1%) and HCV (anti-HCV-positive 90.7%). Of those 159 IVDUs negative at baseline for anti-HBc and/or anti-HCV, 56 (35%) seroconverted to one or both viruses during follow-up, corresponding to 11.7 seroconversions/100 y at risk for HBV and 26.3 seroconversions/100 y for HCV. Multiple logistic regression analysis showed hepatitis seroconversion to correlate with imprisonment during the study (OR 2.2; 95% CI 1.04-4.74), absence of drug-free periods (OR 5.7; CI 1.44-22.3) and frequent syringe/needle exchanges (OR 1.31; CI 1.02-1.7). The absence of HIV spread was probably partly due to the low prevalence of HIV-infected IVDUs in the city. Despite free syringes and needles, both HBV and HCV continued to spread at high rates. Nevertheless, syringe/needle exchange programs, coupled with monitoring of serostatus provide good surveillance and are valuable for further assessment of remaining risks.

Nordic biological specimen banks as basis for studies of cancer causes and control - More than 2 million sample donors, 25 million person years and 100 000 prospective cancers

The Nordic countries have a long tradition of large-scale biobanking and comprehensive, population-based health data registries linkable on unique personal identifiers, enabling follow-up studies spanning many decades. Joint Nordic biobank-based studies provide unique opportunities for longitudinal molecular epidemiological research. The purpose of the present paper is to describe the possibilities for such joint studies, by describing some of the major Nordic biobank cohorts with a standardised calculation of the cancer incidence in these cohorts. Altogether two million donors have since 1966 donated more than four million biological samples, stored at −20°C to −135°C, to 17 biobank cohorts in Finland, Iceland, Norway and Sweden. As a result of joint database handling principles, the accuracy of personal identifiers and completeness of follow-up for vital status in all participating biobanks was improved. Thereafter, the cancer incidence was determined using follow-up through the national cancer registries. Biobanks based on random samples of population typically showed slightly lower cancer incidence rates than the general population, presumably due to better participation rates among health-conscious subjects. On the other hand, biobanks including samples for viral screening or clinical testing showed 1.5 to 2.1 fold increased incidence of cancer. This excess was very high immediately after sampling, but for some cancer sites remained elevated for years after clinical sampling. So far, more than 100 000 malignant neoplasms have occurred after sample donation, and the annual increase of the cancer cases in these cohorts is about 10 000. The estimates on the population-representativity of the biobanks will assist in interpretation of generalizability of results of future studies based on these samples, and the systematic tabulations of numbers of cancer cases will serve in study power estimations. The present paper summarizes optimal study designs of biobank-based studies of cancer.

Extrahepatic manifestations of chronic hepatitis C infection and the interrelationship between primary Sjögren's syndrome and hepatitis C in Swedish patients.

Objective. To analyse the frequency of some extrahepatic manifestations of chronic hepatitis C virus (HCV) infection in northern European patients, including a postulated association between HCV and primary Sjögrens syndrome (SS).