Multilocus Sequence Typing of <i>Borrelia burgdorferi</i> Suggests Existence of Lineages with Differential Pathogenic Properties in Humans

<div><p>The clinical manifestations of Lyme disease, caused by <i>Borrelia burgdorferi,</i> vary considerably in different patients, possibly due to infection by strains with varying pathogenicity. Both rRNA intergenic spacer and <i>ospC</i> typing methods have proven to be useful tools for categorizing <i>B. burgdorferi</i> strains that vary in their tendency to disseminate in humans. Neither method, however, is suitable for inferring intraspecific relationships among strains that are important for understanding the evolution of pathogenicity and the geographic spread of disease. In this study, multilocus sequence typing (MLST) was employed to investigate the population structure of <i>B. burgdorferi</i> recovered from human Lyme disease patients. A total of 146 clinical isolates from patients in New York and Wisconsin were divided into 53 sequence types (STs). A goeBURST analysis, that also included previously published STs from the northeastern and upper Midwestern US and adjoining areas of Canada, identified 11 major and 3 minor clonal complexes, as well as 14 singletons. The data revealed that patients from New York and Wisconsin were infected with two distinct, but genetically and phylogenetically closely related, populations of <i>B. burgdorferi</i>. Importantly, the data suggest the existence of <i>B. burgdorferi</i> lineages with differential capabilities for dissemination in humans. Interestingly, the data also indicate that MLST is better able to predict the outcome of localized or disseminated infection than is <i>ospC</i> typing.</p></div

Geographical distribution of <i>B. burgdorferi ospC</i> major groups found in skin of Lyme disease patients from New York and Wisconsin.

a<p>New York data (n = 290) based on <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0073066#pone.0073066-Wormser4" target="_blank">[19]</a>. One additional isolate (E3) was added from <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0073066#pone.0073066-Hanincova1" target="_blank">[13]</a>.</p>b<p><i>ospC</i> major group designation according to <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0073066#pone.0073066-Barbour1" target="_blank">[8]</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0073066#pone.0073066-Wang1" target="_blank">[12]</a>. <i>ospC</i> major groups X and Y were not published at the time this article was written but are available in GenBank under accession numbers HM047876 and HM047875 respectively.</p

Unrooted ML tree of <i>B. burgdorferi</i> based on concatenated sequences of eight MLST housekeeping genes.

<p>The tree was created using data from this study and the previously published data sets downloaded from <a href="http://borrelia.mlst.net/" target="_blank">http://borrelia.mlst.net/</a><a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0073066#pone.0073066-Margos1" target="_blank">[7]</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0073066#pone.0073066-Ogden1" target="_blank">[41]</a>–<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0073066#pone.0073066-Hoen1" target="_blank">[43]</a>. A total of 420 <i>B. burgdorferi</i> samples (88 STs) found in humans and ticks from the northeastern United States and Canada were used. The aLRT statistical values and nonparametric bootstrap values for highly supported nodes in both maximum parsimony (with >70% support) and maximum likelihood (with aLRT >0.9 support) are indicated above and below the branches, respectively. STs newly identified in this study are in bold. The grouping of STs into major clonal complexes (CCs) is indicated by right brackets. The STs found only in humans are shown in blue, those found only in ticks are shown in red and those found in both humans and ticks are shown in green. The type of infection is indicated next to the ST using solid square (ST found in patients with localized infection), solid triangle (ST found in patients with disseminated infection) and solid diamond (ST found in both patients with localized and patients with disseminated infection). Geographical origin of STs found in humans and identified in this study is indicated in brackets next to the STs (NY – New York; WI – Wisconsin).</p

Distribution of <i>B. burgdorferi</i> STs between Lyme disease patients with disseminated and localized infection.

a<p>Only STs that are represented by ≥2 isolates with available clinical data are shown.</p><p>STs, sequence types.</p

Distribution of <i>B. burgdorferi</i> isolates from Lyme disease patients with localized and disseminated infection between clonal complexes and singletons.

<p>Distribution of <i>B. burgdorferi</i> isolates from Lyme disease patients with localized and disseminated infection between clonal complexes and singletons.</p