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Letter to the Editor

The 2 Simultaneously Published “k” Sequence Variants of tp0548 Locus of Treponema pallidum ssp. pallidum Isolates Differ

The One Published Later Has to Be Renamed as “l”

Grillová, Linda MS; Strouhal, Michal PhD; Mikalová, Lenka PhD; Šmajs, David MD, PhD

Author Information
Sexually Transmitted Diseases: January 2015 - Volume 42 - Issue 1 - p 53
doi: 10.1097/OLQ.0000000000000220
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To the Editor

We read with interest the recently published report “Molecular typing of Treponema pallidum: Identification of a new sequence of tp0548 gene in Shandong, China” published in Sexually Transmitted Diseases (Vol. 41, No. 9, September 2014) by Tian et al.1 The authors mapped the diversity of Treponema pallidum ssp. pallidum isolates in Shandong, China, using the enhanced Centers for Disease Control and Prevention typing scheme2,3 and discovered a new sequence variant in the tp0548 locus that was designated type “k”. At the same time, a molecular typing study of syphilis-causing strains isolated in 2011 to 2013 in the Czech Republic published by Grillová et al.4 also identified a new tp0548 sequence variant. By coincidence, caused by almost the same publication dates, this sequence type was also designated type k. However, both tp0548 k types published by Tian et al.1 and Grillová et al.4 differ in their sequences.

So far, 12 different sequence variants of the 83nt-long tp0548 gene fragment (positions 130–212 in tp0548 of T. pallidum Nichols, CP004010)5 have been described in the literature,1,2,4,6 which also includes both of the recently published k variants (Fig. 1). Since Tian and colleagues1 published their work in September 2014 and Grillová et al.4 in August 2014, we suggest that the type k allele, described by Tian et al.,1 be renamed with the next alphabetical letter, “l.”

Figure 1
Figure 1:
Overview of Treponema pallidum 83nt-long tp0548 gene fragment sequences published so far. Sequence types classified as “a–i” were originally described in the work of Marra and coworkers.2 Sequence type “j” was newly identified by Grange et al.6, sequence type k was described in the work of Grillová et al.4 The type k identified by Tian et al.4 is shown in bold and represents novel sequence variant we suggest to rename as type “l”. Coordinates are shown according to the tp0548 gene of T. pallidum strain Nichols.5

Linda Grillová, MS

Michal Strouhal, PhD

Lenka Mikalová, PhD

David Šmajs, MD, PhD

Department of Biology, Faculty of Medicine, Masaryk University, Brno, Czech Republic

REFERENCES

1. Tian H, Li Z, Li Z, et al. Molecular typing of Treponema pallidum: Identification of a new sequence of tp0548 gene in Shandong, China. Sex Transm Dis 2014; 41: 551.
2. Marra C, Sahi S, Tantalo L, et al. Enhanced molecular typing of Treponema pallidum: Geographical distribution of strain types and association with neurosyphilis. J Infect Dis 2010; 202: 1380–1388.
3. Pillay A, Liu H, Chen CY, et al. Molecular subtyping of Treponema pallidum subspecies pallidum. Sex Transm Dis 1998; 25: 408–414.
4. Grillová L, Pětrošová H, Mikalová L, et al. Molecular typing of Treponema pallidum in the Czech Republic during 2011–2013: Increased prevalence of identified genotypes and of isolates encoding macrolide resistance. J Clin Microbiol 2014. pii: JCM.01292-14.
5. Pětrošová H, Pospíšilová P, Strouhal M, et al. Resequencing of Treponema pallidum ssp. pallidum strains Nichols and SS14: Correction of sequencing errors resulted in increased separation of syphilis treponeme subclusters. PLoS One 2013; 8: e74319.
6. Grange PA, Allix-Beguec C, Chanal J, et al. Molecular subtyping of Treponema pallidum in Paris, France. Sex Transm Dis 2013; 40: 641–644.
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