LARGE-SCALE ANALYSIS OF HEPATITIS-C VIRUS SEROLOGICAL TYPING ASSAY - EFFECTIVENESS AND LIMITS

The HCV (hepatitis C virus) Serotyping 1-6 Assay(TM) (Murex Laboratori es) was evaluated on 303 French HCV-infected patients. Serological typ ing results were compared to the genotypes obtained from sequence anal yses of the 5' noncoding regions of the virus genome from 46 HCV-infec ted patients, and assay specificity was found to be high (97.6%). The serological typing assay, run in 257 consecutive HCV-infected patients , yielded an assay sensitivity lower (70.6%) than that previously repo rted. This finding was attributed mainly to nonreactive sera from huma n immunodeficiency virus (HIV)-positive patients (P < 0.001) and perha ps reflected cryoglobulin positivity in others. No anti-type 6 reactiv ity was detected, and the overall serological type distribution values for types 1 to 5 were 67.3, 7.9, 16.4, 6.6, and 0.9%, respectively. A higher prevalence of type 4 was noted among HIV-infected patients (P < 0.001). In addition, serotype 2 was significantly more frequent in c ryoglobulinemia positive than in cryoglobulinemia-negative patients (P < 0.05). Although an initial high level (7%) of mixed serological typ ing reactivities was found, after predilution of serum only two mixed infections could be confirmed (0.9%). It is suggested, therefore, that mixed reactivities have to be interpreted carefully and retested with prediluted serum, particularly when the optical density of the reacti vity is >2.5 or remains >0.4 after competition with all type-specific peptides. The high specificity and relatively good sensitivity even in immunocompromised patients obtained with this assay indicate that it can be used routinely. Because response to treatment is linked to HCV type, this assay could be used to identify HCV serotype to guide thera peutic decisions. (C) 1998 Wiley-Liss, Inc.