Evaluation of three different hepatitis C virus typing methods for detection of mixed-genotype infections

OBJECTIVE: To evaluate the clinical applicability of an eligible assay for the true prevalence of hepatitis C virus (HCV) mixed-genotype infections. METHODS: A newly developed HCV genotyping method targeting all six major HCV genotypes and 12 subtypes, restriction fragment length polymorphism (RFLP) and a serotyping assay were utilized for the detection of HCV mixed-genotype infections using known HCV genotypes and unknown samples. RESULTS: In a defined mix of HCV genotypes, a genotype present at levels as low as 8.3% was detected by our newly developed assay, showing a threefold increase in sensitivity over that of direct deoxyribonucleic (DNA) sequencing. A comparative study of the accuracy among the three genotyping methods was carried out on samples obtained from 50 thalassemic patients who received multiple blood transfusions. The results showed that viruses in approximately 42% of the samples from this group were determined to be infected with mixed genotypes by our newly developed method. A serotyping assay and RFLP analysis, performed with poor results, could identify only 18% and 10% of mixed-genotype infections, respectively. CONCLUSION: The newly developed assay may be the method of choice when detection of genotypes present at low levels in mixed-genotype infections due to its higher level of sensitivity.