- Autores: Fingerle V, Lopes N, Maia C, Nunes M, Parreira R, Vieira ML
- Ano de Publicação: 2016
- Journal: Infection Genetics and Evolution
- Link: https://www.ncbi.nlm.nih.gov/pubmed/26976475
Molecular identification of Borrelia genus
Several studies reported pathogenic species of Borrelia related to those that cause Tick-borne Relapsing Fever (RF). However, this studies unexpectedly suggested their transmission by hard ticks rather than by soft ticks.
This study aimed to update the presence of B. burgdorferi s.l. species in ticks from several districts of Portugal, where Ixodes ricinus was previously described. The authors colleted the Ticks and analyzed them using molecular methods. For the detection of Borrelia DNA they used three nested-PCR protocols (targeting the flagellin gene (flaB), the intergenic spacer region (IGS) located between 5S and 23S rRNA, and the glpQ gene, and a conventional PCR targeting the 16S rRNA).
The authors detected Borrelia DNA in 3% of the ticks from Braga, Vila Real, Lisboa, Setúbal, Évora and Faro districts. They also sequenced and analyzed by BLASTn the obtained amplicons. From these amplicons 15/63 (24%) matched with homologous sequences from Borrelia lusitaniae and 15/63 (24%) with B. garinii, being these the most prevalent species. Moreover, they detected DNA from B. burgdorferi sensu stricto (s.s.), B. valaisiana and B. afzelii in 7/63 (11%), 6/63 (10%), and 2/63 (3%) of the specimens, respectively. Unexpectedly, DNA sequence (flaB) analysis from eight (13%) samples revealed high homology with RF-like Borrelia.
Phylogenetic analyses obtained from three genetic markers (16S rRNA, flaB, and glpQ) confirmed their congruent inclusion in a strongly supported RF cluster. This cluster was segregated in two subgroups which differ from the other Relapsing Fever species. Therefore, the results confirm the circulation of multiple species of B. burgdorferi s.l. over a wide geographic range of Portugal. Surprisingly, the obtained data also revealed two putative Relapsing Fever-like Borrelia species in different species of hard ticks. Possibly disclosing the circulation of novel RF-like Borrelia species with different associated tick vectors.