Evolutionary conservation of mycoplasma symbiosis across the host species barrier.

INTRODUCTION

The protozoan parasite is the most common cellular sexually transmitted disease in humans, and the closely related species is an avian parasite of ecological and economic importance. Phylogenetic evidence suggests arose during bird to human transmission of a -like ancestor. shares a strong clinical association with the independent sexually transmitted pathogen (formerly ) , and the uncultured bacterium " Malacoplasma (formerly ) girerdii," with the latter association being an order of magnitude stronger. Both bacterial species have been shown to profoundly influence growth, energy production and virulence-associated mechanisms.

METHODS

Evidence for a novel sp. was discovered by Illumina metatranscriptomics sequencing of the -infected pigeon mouth. We leveraged published 16S rDNA profiling data from digestive tract of 12 healthy and 24 -infected pigeons to investigate association between the novel sp. and . We utilised Illumina metagenomics sequencing targeted to pigeon oral and crop samples infected with the novel sp. to generate its full-length genome sequence. Sequence similarity network analysis was used to compare annotated proteins from the novel sp. with a range of other related species.

RESULTS

Here we present evidence for a novel species, related to " M. girerdii," that is strongly associated with in the upper digestive tract of domestic pigeons. Analysis of the genome sequence revealed gene features apparently specific to a -symbiotic lineage.

DISCUSSION

These data support a model of long-term association between and spp. that has been conserved across diversification of the lineage and the host species barrier from birds to human.