Borrelia sinica sp nov., a Lyme disease-related Borrelia species isolated in China

A survey was performed for Lyme disease borrelia in the southern part of China, in Zhejiang, Sichuan and Anhui provinces, along the Yangtze River valley, in May of 1997 and 1998. Twenty isolates from Ixodes granulatus, Ixodes ovatus, Apodemus agrarius and Niviventer confucianus were obtained. These isolates were characterized by RFLP of the 5S-23S rDNA intergenic spacer, sequence analysis of the intergenic spacer, 16S rDNA and flagellin gene, DNA-DNA hybridization analysis, SDS-PAGE and Western blotting with mAbs. Six isolates from A. agrarius, five from I. granulatus collected in Zhejiang province and one from N. confucianus in Sichuan province were highly similar to strains 10MT and SMT isolated in Korea and classified as Borrelia valaisiana. Four isolates from A. agrarius and I. granulatus collected in Zhejiang province generated unique RFLP patterns and phylogenetic analysis of the 16S rDNA and flagellin gene sequences suggested that the isolates should be classified as B. valaisiana. Furthermore, three isolates (CMN1a, CNM2, CMN3(T)) from N. confucianus captured in Sichuan province and one (CWO1) from I. ovatus in Anhui province showed lower 16S rDNA sequence similarity (less than 99.0%) to sequences of previously described Lyme disease-related Borrelia species. DNA-DNA hybridization results revealed that strains CMN3(T) and CMN1a were clearly distinct from all other known Lyme disease Borrelia species. Electron microscope observation showed the spirochaetes to be morphologically similar to those of Borrelia, but the cells contained only four periplasmic flagella inserted at each end of the spirochaetes. Based on these results, a new Borrelia species, Borrelia sinica sp. nov., is proposed. Strain CMN3(T) is the type strain of this new species.