Genotyping of clinical varicella-zoster virus isolates collected in China

Varicella-zoster virus (VZV) is genetically stable; and various schemes for the genotyping of VZV based on restriction fragment length polymorphisms (RFLPs), PCR, and sequencing have been developed. At least three major genotypes have been recognized among VZV isolates or clinical samples from different locations around the world; however, few data were available for viral isolates from China. In the current study, a collection of 19 VZV isolates from patients with zoster or varicella in the middle eastern region of China was examined for genetic variations. RFLP analysis of DNA fragments of open reading frames (ORFs) 38, 54, and 62 showed that all 19 isolates were PstI and BglI positive and SmaI negative, and this may represent the major restriction pattern of wild-type VZV strains in China. Further analysis of the R5 variable-repeat region in those strains revealed that 9 (47.4%) were type R5A, while the remaining 10 strains (52.6%) were type R5B. On the basis of the sequencing data for ORFs 1, 21, 22, and 54, all 19 Chinese strains could be grouped into genotype J or J1. A novel in-frame 3-nucleotide insertion (CGG) in ORF1 was found in 4 (21%) of the 19 isolates. Additionally three new nucleotide substitutions were detected in two of the isolates. A varicella isolate from the United States, strain MLS, was included in this study as a control for American wild-type VZV, and was found to be type M1, which represents one of the minor genotypes in North America.