Candidatus Rickettsia xinyangensis as Cause of Spotted Fever Group Rickettsiosis, Xinyang, China, 2015

Abstract

In 2015, we evaluated 221 patients with undifferentiated fever and tick bite or animal exposure in Xinyang, China, for Rickettsia infection. Three with mild disease were infected with Candidatus R. xinyangensis, which clustered with R. fournieri and R. vini in phylogenetic analyses. Field investigations suggest Haemaphysalis longicornis ticks might be involved in transmission.

Keywords: Candidatus Rickettsia xinyangensis; China; Haemaphysalis longicornis; Rickettsia; bacteria; field investigation; gltA; htrA; human infection; ompA; ompB; phylogenetic analysis; rickettsiosis; sca4; spotted fever group rickettsiae; ticks; vector-borne infections.

Figure

Phylogenetic analysis of concatenated nucleotide sequence of novel spotted fever group Rickettsia, Candidatus R. xinyangensis (bold), Xinyang, China, 2015. The partial nucleotide sequences of genes htrA (421 bp), gltA (1,092 bp), ompA (332 bp), ompB (456 bp), and sca4 (245 bp) were concatenated and compared via the maximum-likelihood method by using the best substitution model found (i.e., Tamura 3-parameter plus gamma) and MEGA version 5.0 (http://www.megasoftware.net). A bootstrap analysis of 1,000 replicates was applied to assess the reliability of the reconstructed phylogenies, and bootstrap values are indicated at branch nodes. Scale bar indicates the number of substitutions per nucleotide position. Str., strain. *Sequence includes the htrA gene from R. sibirica str. 246 (GenBank accession no. AABW01000001) and gltA (accession no. HM050296), ompA (accession no. HM050272), ompB (accession no. HM050273), and sca4 (accession no. HM050295) genes from str. RH05. †Sequence includes the htrA (accession no. KT187396), gltA (accession no. KT187394), and ompA (accession no. KT326194) genes from R. vini str. Breclav; ompB from str. 4GA09_32 (accession no. JF758826); and sca4 from str. IA-CR (accession no. KX159443).