Novel Borrelia species detected in echidna ticks, Bothriocroton concolor, in Australia

Siew-May Loh; Alexander W Gofton; Nathan Lo; Amber Gillett; Una M Ryan; Peter J Irwin; Charlotte L Oskam

doi:10.1186/s13071-016-1627-x

Novel Borrelia species detected in echidna ticks, Bothriocroton concolor, in Australia

Parasit Vectors. 2016 Jun 14;9(1):339. doi: 10.1186/s13071-016-1627-x.

Authors

Siew-May Loh¹, Alexander W Gofton¹, Nathan Lo², Amber Gillett³, Una M Ryan¹, Peter J Irwin¹, Charlotte L Oskam⁴

Affiliations

¹ Vector and Water-Borne Pathogen Research Laboratory, School of Veterinary and Life Sciences, Murdoch University, Perth, Western Australia, Australia.
² School of Biological Sciences, The University of Sydney, Sydney, New South Wales, Australia.
³ Australia Zoo Wildlife Hospital, Beerwah, Queensland, Australia.
⁴ Vector and Water-Borne Pathogen Research Laboratory, School of Veterinary and Life Sciences, Murdoch University, Perth, Western Australia, Australia. c.oskam@murdoch.edu.au.

Abstract

Background: To date, little has been documented about microorganisms harboured within Australian native ticks or their pathogenic potential. Recently, a Borrelia sp. related to the Relapsing Fever (RF) group was identified in a single tick removed from a wild echidna (Tachyglossus aculeatus). The present study investigated the presence of Borrelia in 97 Bothriocroton concolor ticks parasitizing echidnas in Queensland, New South Wales, and Victoria, Australia, using nested PCR with Borrelia-specific primers targeting the 16S rRNA (16S) and flaB genes.

Results: Borrelia-specific PCR assays confirmed the presence of a novel Borrelia sp. related to the RF and reptile-associated (REP) spirochaetes in 38 (39 %) B. concolor ticks. This novel Borrelia sp. was identified in 41 % of the B. concolor ticks in Queensland and New South Wales, but not in any ticks from Victoria. The resulting flaB sequences (407 bp) were 88 and 86 % similar to the flaB sequences from Borrelia turcica and Borrelia hermsii, respectively. Of the ticks confirmed as Borrelia-positive following the flaB assay, 28 were positive with the 16S assay. Phylogenetic analysis of the 16S sequences (1097 bp) suggests that these sequences belong to a novel Borrelia sp., which forms a unique monophyletic clade that is similar to, but distinct from, RF Borrelia spp. and REP-associated Borrelia spp.

Conclusions: We conclude that the novel Borrelia sp. identified in this study does not belong to the Borrelia burgdorferi (sensu lato) complex, and that the phylogenetic analysis of the partial 16S gene sequences suggests it forms a unique monophyletic cluster in the genus Borrelia, potentially forming a fourth major group in this genus associated with monotremes in Australia. However, a thorough molecular characterisation will be required to confirm the phylogenetic position of this unique Borrelia sp. The zoonotic potential and pathogenic consequences of this novel Borrelia sp. are unknown at the current time.

Keywords: Australia; Borrelia; Bothriocroton concolor; Echidna; Tick-borne disease.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Animals
Australia
Borrelia / classification*
Borrelia / genetics
Borrelia / isolation & purification*
Ixodidae / microbiology*
Phylogeny
Polymerase Chain Reaction
RNA, Bacterial / genetics
RNA, Ribosomal, 16S / genetics

Substances

RNA, Bacterial
RNA, Ribosomal, 16S