GENETIC AND SEROLOGICAL EVIDENCE FOR MULTIPLE INSTANCES OF UNRECOGNIZED TRANSMISSION OF HEPATITIS-C VIRUS IN HEMODIALYSIS UNITS

We investigated the unrecognized patient-to-patient transmission of he patitis C virus (HCV) in hemodialysis units by performing phylogenetic and serological analyses of hypervariable region 1 (HVR1) of HCV, Of the 62 patients in one center, 11 were positive for HCV RNA. A total o f 24 HVR1 sequences, including the minor population of sequences of HC V isolates, from each patient were closely related and classified into live clusters by phylogenetic analysis, Of the 11 patients, 5 were in fected with multiple clusters of HCV. Two patients were infected with HCV during an 18-month interval between examinations, and these HVR1 s equences fell into one of the five clusters. In another hemodialysis c enter, 5 of the 20 patients were HCV RNA positive, and two HVR1 sequen ces were found to he closely related and phylogenetically derived from the same cluster, The antibody responses of these patients to the HVR 1 peptides representative of the genetic clusters revealed exactly the same clustering as that shown by phylogenetic analysis. These finding s suggest that phylogenetic and serological analyses of HVR1 sensitive ly detect unrecognized and multiple transmission of HCV occurring with in the same room in hemodialysis centers. Fingerprinting analyses usin g hypervariable regions of infectious agents are useful in identifying the precise route of transmission of infection.