A survey was performed for Lyme disease borrelia in the southern part of Ch
ina, in Zhejiang, Sichuan and Anhui provinces, along the Yangtze River vall
ey, 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, s
equence analysis of the intergenic spacer, 16S rDNA and flagellin gene, DNA
-DNA hybridization analysis, SDS-PAGE and Western blotting with mAbs. Six i
solates from A. agrarius, five from I. granulatus collected in Zhejiang pro
vince and one from N. confucianus in Sichuan province were highly similar t
o strains 10MT and SMT isolated in Korea and classified as Borrelia valaisi
ana. Four isolates from A. agrarius and I. granulatus collected in Zhejiang
province generated unique RFLP patterns and phylogenetic analysis of the 1
6S 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 Borre
lia species. DNA-DNA hybridization results revealed that strains CMN3(T) an
d CMN1a were clearly distinct from all other known Lyme disease Borrelia sp
ecies. Electron microscope observation showed the spirochaetes to be morpho
logically similar to those of Borrelia, but the cells contained only four p
eriplasmic flagella inserted at each end of the spirochaetes. Based on thes
e results, a new Borrelia species, Borrelia sinica sp. nov., is proposed. S
train CMN3(T) is the type strain of this new species.