Clustering of Polymorphic Membrane Protein E Clade in Chlamydia trachomatis Lineages from Men Who Have Sex with Men

Abstract

Several Chlamydia trachomatis lineages identified through outer membrane protein A genotyping or multilocus sequence typing have been circulating worldwide among men who have sex with men. In a study in Tokyo, Japan, we demonstrate that such lineages commonly belong to a specific polymorphic membrane protein E clade across genotypes.

Keywords: Chlamydia trachomatis; Japan; bacteria; men who have sex with men; multilocus sequence typing; outer membrane protein A; phylogenetic analysis; polymorphic membrane protein; sexually transmitted infections.

Figure 1

Minimum spanning tree based on sequence types (STs) and ompA of 298 Chlamydia trachomatis samples in study of clustering of specific polymorphic membrane protein E clade in C. trachomatis lineages from MSM, Japan. Each node indicates the ST number. SLVs and DLVs are linked. Samples from MSM are outlined in red, reflecting the proportion of samples in each node. The colors represent the ompA genotype. Nodes that contain several genotypes are shown as pie charts. Dashed lines are the assumed borders between the MSM and non-MSM lineages. DLV, double-locus variant; MSM, men who have sex with men; SLV, single-locus variant.

Figure 2

Nonrooted phylogenetic tree created on the basis of polymorphic membrane protein E of 298 Chlamydia trachomatis samples in study of clustering of specific polymorphic membrane protein E clade in C. trachomatis lineages from MSM, Japan. A) Cluster of 96.7% MSM (237 samples) and 0% non-MSM (0 samples); B) cluster of 3.3% MSM (8 samples) and 100% non-MSM (53 samples). p1 and p2 are 2 clades representing the MSM (p1) and non-MSM (p2) populations. The amino acid sequences of p1–1 to p2–10 are shown in Appendix 2 Figure. Numbers of samples included in each sequence: p1-1, n = 178; p1-2, n = 56; p1-3, n = 1; p1-4, n = 1; p1-5, n = 1; p2-1, n = 16; p2-2, n = 14; p2-3, n = 10; p2-4, n = 9; p2-5, n = 6; p2-6, n = 2; p2-7, n = 1; p2-8, n = 1; p2-9, n = 1; and p2-10, n = 1. Scale bar indicates the number of amino acid differences.

Figure 3

Minimum spanning tree based on sequence types (STs) and polymorphic membrane protein E (PmpE) of 298 Chlamydia trachomatis samples in study of clustering of specific PmpE clade in C. trachomatis lineages from MSM, Japan. Each node indicates the ST number. SLVs and DLVs are linked. Samples from MSM are outlined in red, reflecting the proportion of samples in each node. The PmpE clades p1 and p2 are colored using the same color codes as those used in Figure 2. Dashed lines are the assumed borders between the MSM and non-MSM lineages. DLV, double-locus variant; MSM, men who have sex with men; SLV, single-locus variant.