Use of Phylogenetic Analysis of Hepatitis C Virus (HCV) Hypervariable Region 1 Sequences To Trace an Outbreak of HCV in an Autodialysis Unit

Abstract

Hemodialysis patients are at high risk of infection by hepatitis C virus (HCV). The aim of this study was to investigate an HCV outbreak that occurred in an autodialysis unit by using epidemiological and molecular methods. Seroconversion to HCV antibody (anti-HCV) was observed in two patients over an 18-month period; two other patients had previously been recorded as anti-HCV positive. All four patients involved in the outbreak were tested for HCV RNA, and hepatitis C genotype determination was accomplished by a reverse hybridization assay. Furthermore, part of hypervariable region 1 (HVR1) of the hepatitis C genome was amplified and sequenced in samples from all HCV RNA-positive patients. Phylogenetic analysis of the nucleotide sequences obtained was carried out in order to investigate any possible epidemiological linkages among patients. The nucleotide sequences of the HVR1 regions of both newly infected patients were found to be identical to sequences of samples from previously recorded anti-HCV-positive original patients, suggesting that they were infected by the same isolate. Molecular and epidemiological analysis suggested that nosocomial patient-to-patient transmission was the most likely explanation for the virus spread in the autodialysis unit under study.Hemodialysis is known to be a risk factor for Hepatitis C virus (HCV) transmission despite screening of blood products for HCV antibodies (anti-HCV) and the use of erythropoietin (1). Nosocomial transmission of the HCV has become the principal cause of HCV infection in hemodialysis units (10-12, 14, 20, 21). Such transmission occurs through direct patientto-patient contact more often than through HCV-contaminated dialysis monitors (13). There remains a relatively high incidence of new infections in hemodialysis units, mainly through cross-contamination from HCV hemodialysis patients (8,17). The prevalence of infection increases with the duration of dialysis treatment, independent of transfusion events (5, 6). The exact mechanism of the route of this contamination is rarely known, and the causal events that lead to the outbreak cannot generally be traced (15). These cases of nosocomial transmission seem to have occurred despite strict general hygiene precautions. The prevalence of HCV infections is not declining, and transmission in dialysis units is continuing. Adequate screening of HCV infections and strict enforcement of universal infection control practices are required (9). Home dialysis and autodialysis were developed as alternatives to hemodialysis centers, and there have been fewer reported HCV infections in the former than in the latter (17).HCV, like other RNA viruses, exhibits enormous genomic diversity. HCV isolates show four levels of genetic variability: types, subtypes, isolates, and quasispecies. This heterogeneity is a consequence of high error rates in RNA replication. HCV circulates as a heterogeneous population of genetically different but closely related genomes known as the quasispecies (2).Hypervariable region 1 (HVR1) of the gen...

Incidence of HCV infection in French hemodialysis units: A prospective study

“…Nosocomial transmission of HCV infection has become the main source of infection in chronic hemodialysis patients rather than transmission by blood-derived products. Molecular phylogenetic analyses have shown that many outbreaks of HCV infection are not linked to the transfusion of packed red blood cells or blood products [Allander et al, 1994;Stuyver et al, 1996;Le Pogam et al, 1998;Izopet et al, 1999;Katsoulidou et al, 1999;Grethe et al, 2000;Halfon et al, 2002;Kokubo et al, 2002].…”

Hepatitis C in Hemodialysis Patients: Current Global Magnitude, Natural History, Diagnostic Difficulties, and Preventive Measures

“…Several recent studies [31, 52, 54, 59, 65, 79,143,144,145,146,147,148,149,150] and one large study [44] reported nosocomial patient-to-patient transmission of HCV infection among HD patients performing phylogenetic analysis of HCV viral isolates. Although the potential sources of nosocomial transmission could be dialyzer reuse, internal contamination of HD monitors, and contaminated hands and articles, the two former mechanisms are almost unlikely [92, 93, 151, 152].…”

Phylogenetic Analysis of Isolated HCV Strains from Tunisian Hemodialysis Patients

“…These isolates appear to represent a new subtype. They should be analyzed in another region of the viral genome, especially in the hyper variable region E1/E2 which, according to many authors, would best reflect the full extent of subtype variations present in the infected individuals (16) or better yet by sequencing the whole genome (24,44).…”

“…Several molecular methods have been used for genotype HCV; nucleotide sequencing of a phylogenetically informative region remains the gold standard (5,16).…”