Molecular typing of Borrelia burgdorferi sensu lato: taxonomic, epidemiological, and clinical implications

Abstract

Borrelia burgdorferi sensu lato, the spirochete that causes human Lyme borreliosis (LB), is a genetically and phenotypically divergent species. In the past several years, various molecular approaches have been developed and used to determine the phenotypic and genetic heterogeneity within the LB-related spirochetes and their potential association with distinct clinical syndromes. These methods include serotyping, multilocus enzyme electrophoresis, DNA-DNA reassociation analysis, rRNA gene restriction analysis (ribotyping), pulsed-field gel electrophoresis, plasmid fingerprinting, randomly amplified polymorphic DNA fingerprinting analysis, species-specific PCR and PCR-based restriction fragment length polymorphism (RFLP) analysis, and sequence analysis of 16S rRNA and other conserved genes. On the basis of DNA-DNA reassociation analysis, 10 different Borrelia species have been described within the B. burgdorferi sensu lato complex: B. burgdorferi sensu stricto, Borrelia garinii, Borrelia afzelii, Borrelia japonica, Borrelia andersonii, Borrelia valaisiana, Borrelia lusitaniae, Borrelia tanukii, Borrelia turdi, and Borrelia bissettii sp. nov. To date, only B. burgdorferi sensu stricto, B. garinii, and B. afzelii are well known to be responsible for causing human disease. Different Borrelia species have been associated with distinct clinical manifestations of LB. In addition, Borrelia species are differentially distributed worldwide and may be maintained through different transmission cycles in nature. In this paper, the molecular methods used for typing of B. burgdorferi sensu lato are reviewed. The current taxonomic status of B. burgdorferi sensu lato and its epidemiological and clinical implications, especiallly correlation between the variable clinical presentations and the infecting Borrelia species, are discussed in detail.

FIG. 1

Relationship between species and OspA and OspC serotypes of B. burgdorferi sensu lato. OspA serotype J10 of Japanese isolates corresponds to the European B. afzelii strains of serotype 2. Data from references and are included. Adapted from reference with permission of the publisher.

FIG. 2

Simplified dendrogram of 136 Lyme disease spirochete isolates from different B. burgdorferi sensu lato species based on their RAPD fingerprints. The numbers of isolates for each B. burgdorferi sensu lato species studied is indicated in parenthesis. The size of the vertical bars of the triangles for the four major B. burgdorferi sensu lato species represents the number of isolates studied, while the position of the left angle of these triangles is representative of the percent similarity within each of these species. Modified from reference .

FIG. 3

Typing of B. burgdorferi sensu lato isolates by using the rrfA-rrlB intergenic spacer PCR-RFLP analysis. The rrfA-rrlB intergenic spacer was amplified by PCR, and this was followed by the analysis of MseI restriction polymorphism of PCR products. The eight B. burgdorferi sensu lato species included are B. burgdorferi sensu stricto (pattern A), B. garinii (patterns B and C), B. afzelii (pattern D), B. japonica (pattern E), B. valaisiana (pattern F), B. lusitaniae (pattern G), B. bissettii sp. nov. (pattern I), and B. andersonii (pattern L). Modified from reference with permission of the publisher.

FIG. 4

Phylogeny of Lyme disease spirochete isolates as inferred from 16S rRNA gene sequence analysis. The phylogenetic tree was constructed by using the neighbor-joining method in the MEGA program as described in reference . A total of 28 B. burgdorferi sensu lato isolates representing 10 different Borrelia species were included in this analysis. B. hermsii HS1 was used as the outgroup. The sources of each isolate are given in Table 4. Numbers at the branch nodes indicate the results of bootstrap analysis. The bar represents 0.5% sequence divergence.