The population structure of Borrelia lusitaniae Is reflected by a population division of its Ixodes Vector

© 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).Populations of vector-borne pathogens are shaped by the distribution and movement of vector and reservoir hosts. To study what impact host and vector association have on tick-borne pathogens, we investigated the population structure of Borrelia lusitaniae using multilocus sequence typing (MLST). Novel sequences were acquired from questing ticks collected in multiple North African and European locations and were supplemented by publicly available sequences at the Borrelia Pubmlst database (accessed on 11 February 2020). Population structure of B. lusitaniae was inferred using clustering and network analyses. Maximum likelihood phylogenies for two molecular tick markers (the mitochondrial 16S rRNA locus and a nuclear locus, Tick-receptor of outer surface protein A, trospA) were used to confirm the morphological species identification of collected ticks. Our results confirmed that B. lusitaniae does indeed form two distinguishable populations: one containing mostly European samples and the other mostly Portuguese and North African samples. Of interest, Portuguese samples clustered largely based on being from north (European) or south (North African) of the river Targus. As two different Ixodes species (i.e., I. ricinus and I. inopinatus) may vector Borrelia in these regions, reference samples were included for I. inopinatus but did not form monophyletic clades in either tree, suggesting some misidentification. Even so, the trospA phylogeny showed a monophyletic clade containing tick samples from Northern Africa and Portugal south of the river Tagus suggesting a population division in Ixodes on this locus. The pattern mirrored the clustering of B. lusitaniae samples, suggesting a potential co-evolution between tick and Borrelia populations that deserve further investigation.This research was financially supported by the Slovak Research and Development Agency (grant number APVV-16-0463), by the Fundação para a Ciência e a Tecnologia by the transitory norm contract DL57/2016/CP1370/CT89 to Ana Cláudia Norte and MARE (MARE-UID/MAR/04292/2020), and by the National Institute of Health Doutor Ricardo Jorge, Lisbon, Portugal. The National Reference Center for Borrelia was supported by the Robert-Koch Institute, Berlin, Germany.info:eu-repo/semantics/publishedVersio

There is inadequate evidence to support the division of the genus Borrelia

There are surely scientific, genetic or ecological 60 arguments which show that differences exist between the relapsing fever (RF) spirochaetes and the Lyme borreliosis (LB) group of spirochaetes, both of which belong to the genus Borrelia. In a recent publication, Adeolu and Gupta (Adeolu & 63 Gupta, 2014) proposed dividing the genus Borrelia into two genera on the basis of genetic differences revealed by comparative genomics. The new genus name for the LB group of spirochaetes, Borreliella, has subsequently been entered in GenBank for some species of the group and in a validation list (List of new names and new combinations previously effectively, but not validly, published) (Oren & Garrity, 2015). However, rapidly expanding scientific knowledge and considerable conflicting evidence combined with the adverse consequences of splitting the genus Borrelia make such a drastic step somewhat premature. In our opinion, the basis of this division rests on preliminary evidence and should be rescinded

Driving forces for changes in geographical distribution of Ixodes ricinus ticks in Europe

International audienceMany factors are involved in determining the latitudinal and altitudinal spread of the important tick vector Ixodes ricinus (Acari: Ixodidae) in Europe, as well as in changes in the distribution within its prior endemic zones. This paper builds on published literature and unpublished expert opinion from the VBORNET network with the aim of reviewing the evidence for these changes in Europe and discusses the many climatic, ecological, landscape and anthropogenic drivers. These can be divided into those directly related to climatic change, contributing to an expansion in the tick's geographic range at extremes of altitude in central Europe, and at extremes of latitude in Scandinavia; those related to changes in the distribution of tick hosts, particularly roe deer and other cervids; other ecological changes such as habitat connectivity and changes in land management; and finally, anthropogenically induced changes. These factors are strongly interlinked and often not well quantified. Although a change in climate plays an important role in certain geographic regions, for much of Europe it is non-climatic factors that are becoming increasingly important. How we manage habitats on a landscape scale, and the changes in the distribution and abundance of tick hosts are important considerations during our assessment and management of the public health risks associated with ticks and tick-borne disease issues in 21st century Europe. Better understanding and mapping of the spread of I. ricinus (and changes in its abundance) is, however, essential to assess the risk of the spread of infections transmitted by this vector species. Enhanced tick surveillance with harmonized approaches for comparison of data enabling the follow-up of trends at EU level will improve the messages on risk related to tick-borne diseases to policy makers, other stake holders and to the general public