Characterization and identification of Borrelia isolates as Borrelia valaisiana in Taiwan and Kinmen Islands

Borreliae Part 1: Borrelia Lyme Group and Echidna-Reptile Group

Simple Summary

Borreliae are spirochaetes, which represent a heterogeneous phylum within bacteria. Spirochaetes are indeed distinguished from other bacteria for their spiral shape, which also characterizes Borreliae. This review describes briefly the organization of the phylum Spirocheteales with a digression about its pathogenicity and historical information about bacteria isolation and characterization. Among spirochaetes, Borrelia genus is here divided into three groups, namely the Lyme group (LG), the Echidna-Reptile group (REPG) and the Relapsing Fever group (RFG). Borreliae Part 1 deals with Lyme group and Echidna-Reptile group Borreliae, while the subject of Borreliae Part 2 is Relapsing Fever group and unclassified Borreliae. Lyme group Borreliae is organized here in sections describing ecology, namely tick vectors and animal hosts, epidemiology, microbiology, and Borrelia genome organization and antigen characterization. Furthermore, the main clinical manifestations in Lyme borreliosis are also described. Although included in the Lyme group due to their particular clinical features, Borrelia causing Baggio Yoshinari syndrome and Borrelia mayonii are described in dedicated paragraphs. The Borrelia Echidna-Reptile group has been recently characterized including spirochaetes that apparently are not pathogenic to humans, but infect reptiles and amphibians. The paragraph dedicated to this group of Borreliae describes their vectors, hosts, geographical distribution and their characteristics.

Abstract

Borreliae are divided into three groups, namely the Lyme group (LG), the Echidna-Reptile group (REPG) and the Relapsing Fever group (RFG). Currently, only Borrelia of the Lyme and RF groups (not all) cause infection in humans. Borreliae of the Echidna-Reptile group represent a new monophyletic group of spirochaetes, which infect amphibians and reptiles. In addition to a general description of the phylum Spirochaetales, including a brief historical digression on spirochaetosis, in the present review Borreliae of Lyme and Echidna-Reptile groups are described, discussing the ecology with vectors and hosts as well as microbiological features and molecular characterization. Furthermore, differences between LG and RFG are discussed with respect to the clinical manifestations. In humans, LG Borreliae are organotropic and cause erythema migrans in the early phase of the disease, while RFG Borreliae give high spirochaetemia with fever, without the development of erythema migrans. With respect of LG Borreliae, recently Borrelia mayonii, with intermediate characteristics between LG and RFG, has been identified. As part of the LG, it gives erythema migrans but also high spirochaetemia with fever. Hard ticks are vectors for both LG and REPG groups, but in LG they are mostly Ixodes sp. ticks, while in REPG vectors do not belong to that genus.

Detection of Borrelia burgdorferi Sensu Lato and Relapsing Fever Borrelia in Feeding Ixodes Ticks and Rodents in Sarawak, Malaysia: New Geographical Records of Borrelia yangtzensis and Borrelia miyamotoi

Members of the Borrelia burgdorferi sensu lato (Bbsl) complex are etiological agents of Lyme disease (LD), and Borrelia miyamotoi is one of the relapsing fever Borrelia (RFB). Despite the serological evidence of LD in Malaysia, there has been no report from Sarawak, Malaysian Borneo. Thus, this study aimed to detect and characterize Borrelia in rodents and Ixodes ticks from primary forests and an oil palm (OP) plantation in Sarawak. Borrelia yangtzensis (a member of the Bbsl complex) was detected in 43.8% (14/32) of Ixodes granulatus; most of the positive ticks were from the OP plantation (13/14). Out of 56 rodents, B. yangtzensis was detected in four Rattus spp. from the OP plantation and B. miyamotoi was detected in one rodent, Sundamys muelleri, from the primary forest. Further, the positive samples of B. yangtzensis were randomly selected for multilocus sequence analysis (MLSA). The MLSA results of successfully amplified tick samples revealed a clustering with the sequences isolated from Japan and China. This study is the first evidence of B. miyamotoi, a known human pathogen in Malaysia, and B. yangtzensis, which is circulating in ticks and rodents in Sarawak, Malaysian Borneo, and presenting a new geographical record of the Borrelia spp.

Recurrent evolution of host and vector association in bacteria of the Borrelia burgdorferi sensu lato species complex

Background

The Borrelia burgdorferi sensu lato (s.l.) species complex consists of tick-transmitted bacteria and currently comprises approximately 20 named and proposed genospecies some of which are known to cause Lyme Borreliosis. Species have been defined via genetic distances and ecological niches they occupy. Understanding the evolutionary relationship of species of the complex is fundamental to explaining patterns of speciation. This in turn forms a crucial basis to frame testable hypotheses concerning the underlying processes including host and vector adaptations.

Results

Illumina Technology was used to obtain genome-wide sequence data for 93 strains of 14 named genospecies of the B. burgdorferi species complex and genomic data already published for 18 additional strain (including one new species) was added. Phylogenetic reconstruction based on 114 orthologous single copy genes shows that the genospecies represent clearly distinguishable taxa with recent and still ongoing speciation events apparent in Europe and Asia. The position of Borrelia species in the phylogeny is consistent with host associations constituting a major driver for speciation. Interestingly, the data also demonstrate that vector associations are an additional driver for diversification in this tick-borne species complex. This is particularly obvious in B. bavariensis, a rodent adapted species that has diverged from the bird-associated B. garinii most likely in Asia. It now consists of two populations one of which most probably invaded Europe following adaptation to a new vector (Ixodes ricinus) and currently expands its distribution range.

Conclusions

The results imply that genotypes/species with novel properties regarding host or vector associations have evolved recurrently during the history of the species complex and may emerge at any time. We suggest that the finding of vector associations as a driver for diversification may be a general pattern for tick-borne pathogens. The core genome analysis presented here provides an important source for investigations of the underlying mechanisms of speciation in tick-borne pathogens.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-016-3016-4) contains supplementary material, which is available to authorized users.

Borrelia yangtzensis sp. nov., a rodent-associated species in Asia, is related to Borrelia valaisiana

Twenty-nine isolates of Lyme borreliosis (LB) group spirochaetes collected from ticks and rodents in China and Japan were included in a multilocus sequence analysis (MLSA). Using a different typing system, three of these strains had previously been identified as being divergent from other LB spirochaete species and the name 'Borrelia yangtze' sp. nov. was proposed. The data presented here confirm that the genetic distance, calculated using sequences of MLSA housekeeping genes, to other known LB group spirochaete species was < 95 % and to Borrelia valaisiana was 96.67 % (which represents the most closely related species within the group of LB spirochaetes). This and the fact that these strains are ecologically distinct from B. valaisiana (rodent-transmitted vs bird-transmitted) provide strong support for the validation of the proposed species status. We suggest the name Borrelia yangtzensis sp. nov. The type strain is Okinawa-CW62T ( = DSM 24625T = JCM 17189T).

The expanding Lyme Borrelia complex--clinical significance of genomic species?

Ten years after the discovery of spirochaetes as agents of Lyme disease in 1982 in the USA, three genomic species had diverged from the phenotypically heterogeneous strains of Borrelia burgdorferi isolated in North America and Europe: Borrelia afzelii, B. burgdorferi sensu stricto (further B. burgdorferi), and Borrelia garinii. Whereas B. burgdorferi remained the only human pathogen in North America, all three species are aetiological agents of Lyme borreliosis in Europe. Another seven genospecies were described in the 1990s, including species from Asia (Borrelia japonica, Borrelia turdi, and B. tanukii), North America (Borrelia andersonii), Europe (Borrelia lusitaniae and Borrelia valaisiana), and from Europe and Asia (Borrelia bissettii). Another eight species were delineated in the years up to 2010: Borrelia sinica (Asia), Borrelia spielmanii (Europe), Borrelia yangtze (Asia), Borrelia californiensis, Borrelia americana, Borrelia carolinensis (North America), Borrelia bavariensis (Europe), and Borrelia kurtenbachii (North America). Of these 18 genomic species B. afzelii, B. burgdorferi and B. garinii are the confirmed agents of localized, disseminated and chronic manifestations of Lyme borreliosis, whereas B. spielmanii has been detected in early skin disease, and B. bissettii and B. valaisiana have been detected in specimens from single cases of Lyme borreliosis. The clinical role of B. lusitaniae remains to be substantiated.

Novel genospecies of Borrelia burgdorferi sensu lato from rodents and ticks in southwestern China

By using multilocus sequence analysis, five Borrelia valaisiana-related strains isolated from rodents and ticks in southwestern China were eventually classified as a new genospecies of B. burgdorferi sensu lato rather than B. valaisiana. The finding explained the differences in transmission cycle and phenotype between B. valaisiana strains from Europe and B. valaisiana-related strains from eastern Asia.

New genomospecies related to Borrelia valaisiana, isolated from mammals in Okinawa archipelago, Japan

In 2000 and 2001, a survey was conducted of Borrelia isolated from various mammals in the southernmost islands of Japan, including Okinawa (main island), Izena, Iriomote and Ishigaki. Isolates obtained from the ear tissues of Suncus murinus (10 isolates), Mus calori (four isolates), Rattus norvegicus (one isolate) and Crocidura watasei (one isolate), were characterized by RFLP of the 5S–23S rDNA intergenic spacer and sequence analysis of the intergenic spacer, 16S rDNA and flagellin gene. While these isolates showed identical RFLPs to Borrelia valaisiana found in Korea, Taiwan and the southern and central parts of China, their RFLP patterns differed from those of B. valaisiana found in European countries, and strain Am501 isolated from Ixodes columnae in Japan. It was found that these isolates clustered with each other on a phylogenetic tree based on flagellin gene and 16S rDNA sequences, but were relatively divergent from the European B. valaisiana and strain Am501. These findings suggest that these isolates found in East Asia should be classified as a new genomospecies of Borrelia burgdorferi sensu lato.

First isolation and characterization of Borrelia burgdorferi sensu lato strains from Ixodes ricinus ticks in Turkey

In order to investigate the presence and prevalence of Lyme borreliosis (Lyme disease) Borrelia species, 312 unfed ticks were collected by flagging at a woodland area in Trakya, in the European side of Turkey, in May 2002. Twelve of 299 Ixodes ricinus ticks were infected with Borrelia spp., as determined by cultivation in BSK medium (prevalence rate 4.0 %). Ten pure cultures were subjected to further characterization by sequencing analysis of the 5S-23S rDNA intergenic spacer, 16S rDNA and flagellin gene. One isolate of Borrelia burgdorferi sensu stricto, two of Borrelia garinii (Eurasian type), two of Borrelia afzelii, four of Borrelia lusitaniae and one of Borrelia valaisiana were identified. However, no Asian-type B. garinii was found. Interestingly, all Borrelia species that are known to be carried by I. ricinus were discovered among the 10 isolates. These results provide the first evidence for the existence of the Lyme borreliosis agent in Turkey.

Negative incidence of Lyme disease-related Borrelia spp. in Alishan, Taiwan

To investigate the prevalence of Lyme disease-related Borrelia species, wild rodents were captured around Yushan National Park and Alishan Forest Recreation Area Park in Taiwan 2,000 to 3,000 meters above sea level. Borrelia was not isolated from 67 small mammals of 7 species. Sera from rodents showed no positive reactivity against whole cell antigens of B. garinii, B. afzelii or B. valaisiana by ELISA. These results suggested that Lyme disease is not endemic to the Alishan area.