Genetic Diversity of Borreliaceae Species Detected in Natural Populations of Ixodes ricinus Ticks in Northern Poland

Abstract

In Europe, Ixodes ricinus tick is the vector of Lyme disease spirochetes and their relatives (Borreliella genus) and Borrelia miyamotoi. However, a newly described tick I. inopinatus with similar biological features and separated from I. ricinus may act as a vector for different Borrelia species. To date, eleven Borreliella species were detected in the natural populations of I. ricinus. Recently, two North American species have been detected in ticks parasitizing bats and red foxes in Europe, i.e., B. lanei and B. californiensis pointing to the necessity for searching for them in natural tick populations. In this study, using the coxI molecular marker only I. ricinus was identified in field-collected ticks with the exception of individual specimens of Haemaphysalis concinna. Using the flaB gene and mag-trnI intergenic spacer as molecular markers 14 Borreliaceae species have been detected with various frequencies in different parts of northern Poland. Among infected ticks, the most frequent were Borreliella (Bl.) afzelii (29.4%) and Bl. garinii (20.0%), followed by Bl. spielmanii, Bl. valaisiana, Bl. lanei, Bl. californiensis, B. miyamotoi, Bl. burgdorferi, Bl. carolinensis, Bl. americana, B. turcica, Bl. lusitaniae, Bl. bissettiae and Bl. finlandensis. Three of the above-mentioned species, i.e., Bl. lanei, Bl. californiensis and B. turcica were detected in this study for the first time in the natural ixodid tick population in Europe. The existence of the newly detected spirochetes increases their total diversity in Europe and points to the necessity of careful identification and establishment of the actual distribution of all Borreliaceae species transmitted by I. ricinus.

Keywords: Borrelia; Borreliaceae; Borreliella; Ixodes ricinus; genetic diversity.

Figure 1

Ixodes ricinus tick collection sites in northern Poland. 1—Lubieszyn, 2—Bartoszewo, 3—Zielonczyn, 4—Ciemnik, 5—Świerznica, 6—Gdańsk, 7—Bełdany Lake.

Figure 2

Phylogenetic analysis of Borreliaceae species obtained on the basis of flaB gene fragment (length 783–789 bp) amplified with primers FL120F and FL908R. The analysis involved 70 sequences. Bootstrap values >50 are shown. (*)—sequences obtained in this study. BG—Borreliella garinii, BA—Bl. afzelii, BB—Bl. burgdorferi, BV—Bl. valaisiana, BL—Bl. lusitaniae, BS—Bl. spielmanii, BBI—Bl. bissettiae, BF—Bl. finlandensis, BCL—Bl. californiensis, BCR—Bl. carolinensis, BLN—Bl. lanei, BAM—Bl. americana, BTC—Borrelia turcica, BM—B. miyamotoi.

Figure 3

Phylogenetic analysis of Borreliaceae species obtained on the basis of mag-trnI intergenic spacer fragment (length 302–1176 bp) amplified with primers glz435f and ile20r. The analysis involved 78 sequences. Bootstrap values >50 are shown. (*)—sequences obtained in this study. BG—Borreliella garinii, BA—Bl. afzelii, BB—Bl. burgdorferi, BV—Bl. valaisiana, BL—Bl. lusitaniae, BS—Bl. spielmanii, BBI—Bl. bissettiae, BF—Bl. finlandensis, BCL—Bl. californiensis, BCR—Bl. carolinensis, BLN—Bl. lanei, BAM—Bl. americana, BTC—Borrelia turcica, BM—B. miyamotoi.