Hepatitis C virus genotypes in French haemophiliacs: kinetics and reappraisal of mixed infections.

The distribution and kinetics of hepatitis C virus (HCV) genotypes and the prevalence of mixed infections were studied in a group of 45 French patients with haemophilia A or B or von Willebrand's disease, 21 of them being anti-human immunodeficiency virus (HIV) positive; genotyping was carried out by three methods based on the core, 5' untranslated region (5'UTR), and the detection of type-specific NS4 antibodies. Genotyping of the 5'UTR revealed genotypes 1a (n = 10), 1b (n = 13), 2a (n = 3), 2b (n = 4), 2NC (n = 3), 3a (n = 10), and two mixed infections (1a + 1b and 3a + 2). Five of 33 patients showed a change from one HCV genotype to another. The core genotyping assay showed 8 of 45 mixed infections: 6/8 1a + 1b and 2/8 3a + 2. Sequencing of core polymerase chain reaction (PCR) products showed that mixed infection 1a + 1b could be explained by nonspecific annealing of the 1b primer to type 1a sequence. By designing new primers whose sequence was more specific to HCV types 1a and 1b, we could confirm 1a + 1b mixed infection in only one of six cases. Serotyping assay showed for 17 of 21 anti-HIV negative patients a concordance with the 5'UTR genotype; however, only 6 of 19 anti-HIV positive patients showed detectable serological reactivity. In summary, we have observed a similar HCV genotype distribution between our haemophilic group and the French anti-HCV positive patients. The study demonstrates the difficulties of assessing with the presently available genotyping and serotyping assays the real prevalence of mixed infections in multiply transfused patients.