SEROLOGICAL DETERMINATION OF HEPATITIS-C VIRUS GENOTYPE - COMPARISON WHICH A STANDARDIZED GENOTYPING ASSAY

In patients with chronic hepatitis C. determination of hepatitis C vir us (HCV) genotype could be routinely run in the future to tailor treat ment schedules. The suitabilities of two versions of a serological, so -called serotyping assay (Murex HCV Serotyping Assay version 1-3 [SA1- 3] and Murex HCV Serotyping Assay version 1-6 [SA1-6]; Murex Diagnosti cs Ltd.), based on the detection of genotype-specific antibodies direc ted to epitopes encoded by the NS4 region of the genome, for the routi ne determination of HCV genotypes were studied. The results were compa red with those of a molecular biology-based genotyping method (HCV Lin e Probe Assay [INNO-LiPA HCV]; Innogenetics S.A.), based on hybridizat ion of PCR products onto genotype-specific probes designed in the 5' n oncoding region of the genome, obtained with pretreatment serum sample s from 88 patients with chronic hepatitis C eligible for interferon th erapy, Definitive genotyping was performed by sequence analysis of thr ee regions of the viral genome in all samples with discrepant typing r esults found among at least two of the three assays studied. In all in stances, sequence analysis confirmed the result of the INNO-LiPA HCV t est. The sensitivity of SA1-3 was 75% relative to the results obtained by the genotyping assay. The results were concordant with those of ge notyping for 92% of the samples typeable by SA1-3, The sensitivity of SA1-6 was 89% relative to the results obtained by the genotyping assay , The results mere concordant with those of genotyping for 94% of the samples typeable by SA1-6. Overall SA1-6 had increased sensitivity rel ative to Sk1-3 but remained less sensitive than the gene typing assay on the basis of PCR amplification of HCV RNA. Cross-reactivities betwe en different HCV genotypes could be responsible for the mistyping of 8 (SA1-3) and 6% (SA1-6) of the samples, Subtyping of 1a and 1b is stil l not possible with the existing peptides, but discriminating between subtypes may not be necessary for routine use.