Metagenomics of Ixodes ticks sampled from Australian wildlife reveal diverse vertebrate viruses and Rickettsia tasmanensis in New South Wales.. Australian hard ticks (Ixodidae)

Ticks are hematophagous vectors of protozoan, viral and bacterial pathogens including Rickettsia spp associated with Scrub typhus and spotted fever group (SFG) disease. In this study hard ticks (Ixodidae) Ixodes tasmani, Ixodes holocyclus and Haemaphysalis bancrofti from animals presented to veterinarian hospitals in South-East Queensland and Central New South Wales were subjected to high throughput genomic DNA sequencing. Metagenomics analysis revealed multiple DNA viruses from a novel genus in the Anelloviridae family and one Circoviridae species.Analysis of bacterial contigs identified a draft genome of an unknown Rickettsia species assembled from I. tasmani ticks sampled from Koalas (Phascolarctos cinereus). Phylogenomic analyses revealed this Rickettsia genome is not any completely sequenced SFG species identified in Australia and is closely related to gene fragments of the previously identified Rickettsia tasmaniensis from Tasmanian devils. This study provides evidence of an additional Rickettsia species present in mainland Australia with the potential to cause human rickettsial disease.