Bacterial community profiling highlights complex diversity and novel organisms in wildlife ticks

Abstract

AbstractTicks (Acari: Ixodida) transmit a greater variety of pathogens than any other blood-feeding group of arthropods. While numerous microbes have been identified inhabiting Australian Ixodidae, some of which are related to globally important tick-borne pathogens, little is known about the bacterial communities within ticks collected from Australian wildlife. In this study, 1,019 ticks were identified on 221 hosts spanning 27 wildlife species. Next-generation sequencing was used to amplify the V1-2 hypervariable region of the bacterial 16S rRNA gene from 238 ticks;Amblyomma triguttatum(n=6),Bothriocroton auruginans(n=11),Bothriocroton concolor(n=20),Haemaphysalis bancrofti(n=10),Haemaphysalis bremneri(n=4),Haemaphysalis humerosa(n=13), Haemaphysalis longicornis(n=4),Ixodes antechini(n=29),Ixodes australiensis(n=26),Ixodes fecialis(n=13),Ixodes holocyclus(n=37),Ixodes myrmecobii (n=1), Ixodes ornithorhynchi(n=10),Ixodes tasmani(n=51) andIxodes trichosuri(n=3). After bioinformatic analyses, over 14 million assigned bacterial sequences revealed the presence of recently described bacteria ‘CandidatusBorrelia tachyglossi’, ‘CandidatusNeoehrlichia australis’, ‘CandidatusNeoehrlichia arcana’ and ‘CandidatusEhrlichia ornithorhynchi’. Furthermore, three novel Anaplasmataceae species were identified in the present study including; aNeoehrlichiasp. inI. australiensisandI. fecialiscollected from quenda (Isoodon fusciventer) (Western Australia), anAnaplasmasp. from oneB. concolorfrom echidna (Tachyglossus aculeatus) (New South Wales), and anEhrlichiasp. from a singleI. fecialisparasitising a quenda (WA). This study highlights the diversity of bacterial genera harboured within wildlife ticks, which may prove to be of medical and/or veterinary importance in the future.