Post by Admin/ Traveler on Sept 10, 2017 19:23:06 GMT
Recurrent evolution of host and vector association in bacteria of the
Borrelia burgdorferi sensu lato species complex. *
Becker NS, Margos G, Blum H, Krebs S, Graf A, Lane RS, Castillo-Ramírez
S, Sing A, Fingerle V.
/BMC Genomics/. 2016 Sep 15;17(1):734.
link to article
Abstract
*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.
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So my main purpose in posting this article was to bring your attention to the "conclusions" portion of this article: "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."
Above this, they state: "This is particularly obvious in /B. bavariensis,/ a rodent adapted species that has diverged from the bird-associated /B. garinii/ most likely in Asia."
So we have Borrelia species jumping to different hosts. Some said it was a matter of time until this happened, what we need to know now is that it IS happening, no matter what part of the world it's currently restricted to, it won't last. We will have more and more Borrelia strains that will start infecting humans as well.
Borrelia burgdorferi sensu lato species complex. *
Becker NS, Margos G, Blum H, Krebs S, Graf A, Lane RS, Castillo-Ramírez
S, Sing A, Fingerle V.
/BMC Genomics/. 2016 Sep 15;17(1):734.
link to article
Abstract
*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.
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
So my main purpose in posting this article was to bring your attention to the "conclusions" portion of this article: "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."
Above this, they state: "This is particularly obvious in /B. bavariensis,/ a rodent adapted species that has diverged from the bird-associated /B. garinii/ most likely in Asia."
So we have Borrelia species jumping to different hosts. Some said it was a matter of time until this happened, what we need to know now is that it IS happening, no matter what part of the world it's currently restricted to, it won't last. We will have more and more Borrelia strains that will start infecting humans as well.