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

Abstract

There are surely scientific, genetic or ecological 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 [1] 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 the GenBank database for some species of the group and in a validation list (List of new names and new combinations previously effectively, but not validly, published) [2]. 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 In our opinion, the basis of this division rests on preliminary evidence and should be rescinded for the following reasons:(1) The proposed split of the genus rests on differences in conserved signature indels (CSI) and conserved signature proteins (CSP) between LB and RF spirochaetes. A major omission in the study published by Adeolu and Gupta [1] is the exclusion of a Borrelia clade containing RF-like species that utilize hard ticks as vectors and reptiles as reservoir hosts [3,4].To identify proteins that are uniquely present in various groups of Borrelia, BLAST searches [5] were performed by Adeolu and Gupta [1] using each protein in the genomes of Borrelia burgdorferi sensu stricto (s.s.) B31 T and Borrelia recurrentis A1 as queries. Out of 1041 and 1390 protein coding genes (i.e. the number of proteins reported in GenBank accession numbers NC_011244 and NC_001318) present in B. recurrentis A1 and B. burgdorferi s.s. B31 T , respectively, 15 CSI (seven for LB, eight for RF) and 25 CSP (21 for LB, four for RF) were found to be unique for the respective groups. However, two of the four CSPs that are apparently unique for the RF group species are not found in all members of this group and therefore do not represent true signature proteins. Hence, just two CSPs and eight CSIs are unique to the RF group.

Division of the genus Borrelia into two genera (corresponding to Lyme disease and relapsing fever groups) reflects their genetic and phenotypic distinctiveness and will lead to a better understanding of these two groups of microbes (Margos et al. (2016) There is inadequate evidence to support the division of the genus Borrelia. Int. J. Syst. Evol. Microbiol. doi: 10.1099/ijsem.0.001717)

“…(iii) This division would have various 'adverse consequences'. While recognizing that a name change for a medically important microbe is never to be taken lightly, we respectfully disagree with the conclusions of Margos et al [7] and discuss point-by-point the issues raised in their letter. We show that much of the criticism of splitting the family Borreliaceae into two genera is unfounded.…”

“…2) in the Adeolu and Gupta [4] article in fact includes B. turcica, which constitutes the species from this group with a validly published name and its position was indicated to be indeterminate based on the presented results. However, in the phylogenetic tree presented by Margos et al [7], which includes B. turcica and other related reptile-associated strains of Borreliaceae without taxonomic standing, these species/strains exhibit the same pattern of branching as described by Takano et al [8], which was acknowledged by Adeolu and Gupta [4]. It should be noted, however, that in other recent studies [9,10], the position of the reptile-associated Borrelia species with respect to its branching position was found to be variable.…”

“…Margos et al [7] also criticised the Adeolu and Gupta [4] article for excluding information for a newly described but relatively uncharacterized group of Borreliaceae species that use reptiles as reservoir hosts. However, this reading of the article is incorrect.…”

“…1 also summarizes and maps the different molecular markers that were identified previously [4], namely conserved signature insertions/deletions (CSIs) and conserved signature proteins (CSPs), which are either specifically characteristic of all Borreliaceae species or uniquely characteristic of one or the other of the two observed clades. Margos et al [7] in their critique did not acknowledge the greater than 100 molecular markers that were described for the family Borreliaceae and they also overlooked 38 other described CSIs (table 4 of Adeolu and Gupta's article [4]), which distinguish the LD and the RF groups of Borreliaceae species.…”

“…Margos et al [7] in a Letter to the Editor in the IJSEM criticized the splitting of the family Borreliaceae into two genera on three major grounds. (i) The evidence based on genomic characteristics distinguishing the two proposed groups was preliminary.…”