Phylogenetic affinities of the Neorickettsia symbiont of Fasciola hepatica.

(A) The genomes of the four fully sequenced Neorickettsia species were aligned. Syntenic blocks are colored. The genome of the Neorickettsia of Fasciola hepatica (PRJNA295290) shares almost complete synteny with the genomes of Neorickettsia risticii (PRJNA19099) and Neorickettsia sennetsu (PRJNA357), with the exception of a small inversion that is also present in Neorickettsia helminthoeca (PRJNA187358). (B) Bayesian inference phylogenetic analysis based on available 16S ribosomal RNA sequences of Neorickettsia species, retrieved from [15]. While the resolution of the sub-clade consisting of Neorickettsia risticii and Neorickettsia sennetsu is sub-optimal, the tree indicates that the Neorickettsia of Fasciola hepatica (nFh) may be most closely related to a strain that occurs in Metagonimoides species and an agent of Sennetsu fever. (C) A Bayesian inference phylogenetic tree based on the protein sequences of 473 single-copy, orthologous protein families conserved in the represented species clearly indicates that nFh is more closely related to N. risticii and N. sennetsu than N. helminthoeca or other species of the family Anaplasmataceae. NCBI GenBank accession numbers are indicated. Trematode hosts or other defining features are indicated for uncharacterized species.