Fig 1. Phylogenetic tree showing the relatedness of 34 representative ORT strains generated from MLST sequences by using the maximum likelihood method of MEGA6 [26].

ORT strains included in the phylogenetic analysis comprised 17 reference strains of serotypes A-Q (RefA-RefQ), 16 field strains mainly from turkeys and chickens of different geographic origins and the ORT type strain DSM 15997. Two main clusters (A and B) and 5 subclusters (Ba-Be) were indicated. Details on sequence type (ST), allelic profile, strain identification (ID), host, geographic origin and serotype were provided. ORT strains that could not be typed with available antisera A to L were indicated by 'n.t.'. Slight serotype cross-reactions in the agar gel precipitation test are given in parentheses. For ORT field strains from China (GB 1707/12), only DNA was available for MLST analysis and the serotype has not yet been determined.