Holocyclus Tick Research Articles

Biotic Factors Influence Microbiota of Nymph Ticks from Vegetation in Sydney, Australia.

Ticks are haematophagous ectoparasites of medical and veterinary significance due to their excellent vector capacity. Modern sequencing techniques enabled the rapid sequencing of bacterial pathogens and symbionts. This study’s aims were two-fold; to determine the nymph diversity in Sydney, and to determine whether external biotic factors affect the microbiota. Tick DNA was isolated, and the molecular identity was determined for nymphs at the cox1 level. The tick DNA was subjected to high throughput DNA sequencing to determine the bacterial profile and the impact of biotic factors on the microbiota. Four nymph tick species were recovered from Sydney, NSW: Haemaphysalis bancrofti, Ixodes holocyclus, Ixodes trichosuri and Ixodes tasmani. Biotic factors, notably tick species and geography, were found to have a significance influence on the microbiota. The microbial analyses revealed that Sydney ticks display a core microbiota. The dominating endosymbionts among all tick species were Candidatus Midichloria sp. Ixholo1 and Candidatus Midichloria sp. Ixholo2. A novel Candidatus Midichloria sp. OTU_2090 was only found in I. holocyclus ticks (nymph: 96.3%, adult: 75.6%). Candidatus Neoehrlichia australis and Candidatus Neoehrlichia arcana was recovered from I. holocyclus and one I. trichosuri nymph ticks. Borrelia spp. was absent from all ticks. This study has shown that nymph and adult ticks carry different bacteria, and a tick bite in Sydney, Australia will result in different bacterial transfer depending on tick life stage, tick species and geography.

Novel hepaci- and pegi-like viruses in native Australian wildlife and non-human primates.

The Flaviviridae family of positive-sense RNA viruses contains important pathogens of humans and other animals, including Zika virus, dengue virus, and hepatitis C virus. The Flaviviridae are currently divided into four genera—Hepacivirus, Pegivirus, Pestivirus, and Flavivirus—each with a diverse host range. Members of the genus Hepacivirus are associated with an array of animal species, including humans, non-human primates, other mammalian species, as well as birds and fish, while the closely related pegiviruses have been identified in a variety of mammalian taxa, also including humans. Using a combination of total RNA and whole-genome sequencing we identified four novel hepaci-like viruses and one novel variant of a known hepacivirus in five species of Australian wildlife. The hosts infected comprised native Australian marsupials and birds, as well as a native gecko (Gehyra lauta). From these data we identified a distinct marsupial clade of hepaci-like viruses that also included an engorged Ixodes holocyclus tick collected while feeding on Australian long-nosed bandicoots (Perameles nasuta). Distinct lineages of hepaci-like viruses associated with geckos and birds were also identified. By mining the SRA database we similarly identified three new hepaci-like viruses from avian and primate hosts, as well as two novel pegi-like viruses associated with primates. The phylogenetic history of the hepaci- and pegi-like viruses as a whole, combined with co-phylogenetic analysis, provided support for virus-host co-divergence over the course of vertebrate evolution, although with frequent cross-species virus transmission. Overall, our work highlights the diversity of the Hepacivirus and Pegivirus genera as well as the uncertain phylogenetic distinction between.

On the cause and consequences of IgE to galactose-α-1,3-galactose: A report from the National Institute of Allergy and Infectious Diseases Workshop on Understanding IgE-Mediated Mammalian Meat Allergy

The mammalian meat allergy known as the "α-Gal syndrome" relates to IgE specific for galactose-α-1,3-galactose (α-Gal), an oligosaccharide that is present in cells and tissues of nonprimate mammals. The recognition of delayed reactions to food derived from mammals in patients with IgE to α-Gal and also the association with tick bites have been increasing worldwide. In 2018, the National Institute of Allergy and Infectious Diseases, Division of Allergy, Immunology and Transplantation, sponsored a workshop on this emerging tick-related disease. International experts from the fields of tick biology, allergy, immunology, infectious disease, and dermatology discussed the current state of our understanding of this emerging medical condition. The participants provided suggestions for specific research priorities and for the development of resources to advance our knowledge of the mechanisms, diagnosis, management, and prevention of this allergic disease. This publication is a summary of the workshop and the panel's recommendations are presented herein.

Molecular surveillance of piroplasms in ticks from small and medium-sized urban and peri-urban mammals in Australia.

Natural landscape alterations as a consequence of urbanisation are one of the main drivers in the movements of wildlife into metropolitan and peri-urban areas. Worldwide, these wildlife species are highly adaptable and may be responsible for the transmission of tick-borne pathogens including piroplasms (Babesia, Theileria and Cytauxzoon spp.) that cause piroplasmosis in animals and occasionally in humans. Little is known about piroplasms in the ticks of urban wildlife in Australia. Ticks from long-nosed bandicoots (Perameles nasuta; n = 71), eastern-barred bandicoots (Perameles gunnii; n = 41), northern-brown bandicoots (Isoodon macrourus; n = 19), southern-brown bandicoots (Isoodon obesulus; n = 4), bandicoot sp. (n = 2), flying foxes (Pteropus sp.; n = 3), black rats (Rattus rattus; n = 7), bush rats (Rattus fuscipes; n = 4), brushtail possums (Trichosurus vulpecula; n = 19), ringtail possums (Pseudocheirus peregrinus; n = 12), short-eared possums (Trichosurus caninus; n = 6), possum sp. (Trichosurus sp.; n = 8), and red foxes (Vulpes vulpes; n = 12) were analysed using piroplasm-specific 18S primers and Sanger sequencing. Seven Ixodes tasmani ticks from long-nosed bandicoots and bandicoots sp., three I. tasmani ticks and one Ixodes holocyclus tick from brushtail possums, and one Haemaphysalis longicornis tick from a red fox were positive for piroplasms. New genotypes, with sequences sharing 98% nucleotide similarities with Theileria sp. K1 detected in a burrowing bettong (Bettongia lesueur), were identified from bandicoot ticks. New genotypes were detected in ticks from brushtail possums, which shared 98% similarity with a Babesia sp. (JQ682877) previously identified in marsupials. Theileria orientalis was identified in the H. longicornis tick from the red fox. Babesia and Theileria spp. in the ticks parasitizing bandicoots and brushtail possums clustered closely with respective Babesia and Theileria clades derived from Australian marsupials. This represents the first detection of piroplasms in ticks parasitizing brushtail possums and a red fox in Australia.

Phylogenetic characterisation of two novel Anaplasmataceae from Australian Ixodes holocyclus ticks: ‘Candidatus Neoehrlichia australis' and ‘Candidatus Neoehrlichia arcana'

Recently, two novel species of Anaplasmataceae were detected in the Australian paralysis tick, Ixodes holocyclus, by 16S rRNA gene metabarcoding. Analysis of these sequences suggested that these novel organisms are closely related to the genus 'Candidatus Neoehrlichia'. In this study, phylogenetic analysis of 16S rRNA (1264 bp), groESL (1047 bp) and gltA (561 bp) gene sequences, and concatenated (2872 bp) sequences, all concur that these novel species belong in the genus 'Candidatus Neoehrlichia' and are most closely related to, but distinct from the only other recognised members of this genus, 'Candidatus Neoehrlichia mikurensis' and 'Candidatus Neoehrlichia lotoris'. Based on their unique molecular signature, we propose to designate these species 'Candidatus Neoehrlichia australis' (reference strain HT41R) and 'Candidatus Neoehrlichia arcana' (reference strain HT94R). Identical 'Candidatus Neoehrlichia australis' 16S rRNA, groESL and gltA sequences were detected in 34/391 (8.7 %) individual Ixodes holocyclus ticks, and sequences were most similar to 'Candidatus Neoehrlichia lotoris' (96.2 %, 83.1 % and 67.2 %, respectively) and 'Candidatus Neoehrlichia mikurensis' (96.2 %, 84 % and 68.4 % respectively). Likewise, identical 'Candidatus Neoehrlichia arcana' 16S rRNA, groESL and gltA sequences were detected in 12/391 (3.1 %) Ixodes holocyclus ticks, and sequences were most similar to 'Candidatus Neoehrlichia lotoris' (98.5 %, 88.7 % and 79.3 %, respectively) and 'Candidatus Neoehrlichia mikurensis' (96.3 %, 84 % and 67.4 % respectively). These new species are the first Anaplasmataceae (except Wolbachia spp.) to be found to be endemic to Australia. The pathogenic consequences of these organisms are yet to be determined.

Ixodes holocyclus Tick-Transmitted Human Pathogens in North-Eastern New South Wales, Australia.

A group of 14 persons who live in an area of Australia endemic for the Australian paralysis tick, Ixodes holocyclus, and who were involved in regularly collecting and handling these ticks, was examined for antibodies to tick-transmitted bacterial pathogens. Five (36%) had antibodies to Coxiella burnetii, the causative agent of Q fever and three (21%) had antibodies to spotted fever group (SFG) rickettsiae (Rickettsia spp). None had antibodies to Ehrlichia, Anaplasma, Orientia, or Borrelia (Lymedisease) suggesting that they had not been exposed to these bacteria. A total of 149 I. holocyclus ticks were examined for the citrate synthase (gltA) gene of the SFG rickettsiae and the com1 gene of C. burnetii; 23 (15.4%) ticks were positive for Rickettsia spp. and 8 (5.6%) positive for Coxiella spp. Sequencing of fragments of the gltA gene and the 17 kDa antigen gene from a selection of the ticks showed 99% and 100% homology, respectively, to Rickettsia australis, the bacterium causing Queenslandtick typhus. Thus, it appears that persons bitten by I. holocyclus in NE NSW, Australia have an approximate one in six risk of being infected with R. australis. Risks of Q fever were also high in this region but this may have been due to exposure by aerosol from the environment rather than by tick bite. A subset of 74 I. holocyclus ticks were further examined for DNA from Borrelia spp., Anaplasma spp. and Ehrlichia spp. but none was positive. Some of these recognised human bacterial pathogens associated with ticks may not be present in this Australian tick species from northeastern New South Wales.

Exploring the transcriptomic data of the Australian paralysis tick, Ixodes holocyclus

AbstractIxodes holocyclus is the paralysis tick commonly found in Australia. I. holocyclus does not cause paralysis in the primary host – bandicoots, but markedly affects secondary hosts such as companion animals, livestock and humans. Holocyclotoxins are the neurotoxin molecules in I. holocyclus responsible for paralysis symptoms. There is a limited understanding of holocyclotoxins due to the difficulties in purifying and expressing these toxins in vitro. Next-generation sequencing technologies were utilised for the first time to generate transcriptome data from two cDNA samples –salivary glands samples collected from female adult ticks engorged on paralysed companion animals and on bandicoots. Contig-encoded proteins in each library were annotated according to their best BLAST match against several databases and functionally assigned into six protein categories: housekeeping, transposable elements, pathogen-related, hypothetical, secreted and novel. The “secreted protein” category is comprised of ten protein families: enzymes, protease inhibitors, antigens, mucins, immunity-related, lipocalins, glycine-rich, putative secreted, salivary and toxin-like. Comparisons of contig representation between the two libraries reveal the differential expression of tick proteins collected from different hosts. This study provides a preliminary description of the I. holocyclus tick salivary gland transcriptome.

Bacterial Profiling Reveals Novel "Ca. Neoehrlichia", Ehrlichia, and Anaplasma Species in Australian Human-Biting Ticks.

In Australia, a conclusive aetiology of Lyme disease-like illness in human patients remains elusive, despite growing numbers of people presenting with symptoms attributed to tick bites. In the present study, we surveyed the microbial communities harboured by human-biting ticks from across Australia to identify bacteria that may contribute to this syndrome. Universal PCR primers were used to amplify the V1-2 hyper-variable region of bacterial 16S rRNA genes in DNA samples from individual Ixodes holocyclus (n = 279), Amblyomma triguttatum (n = 167), Haemaphysalis bancrofti (n = 7), and H. longicornis (n = 7) ticks. The 16S amplicons were sequenced on the Illumina MiSeq platform and analysed in USEARCH, QIIME, and BLAST to assign genus and species-level taxonomies. Nested PCR and Sanger sequencing were used to confirm the NGS data and further analyse novel findings. All 460 ticks were negative for Borrelia spp. by both NGS and nested PCR analysis. Two novel “Candidatus Neoehrlichia” spp. were identified in 12.9% of I. holocyclus ticks. A novel Anaplasma sp. was identified in 1.8% of A. triguttatum ticks, and a novel Ehrlichia sp. was identified in both A. triguttatum (1.2%) ticks and a single I. holocyclus (0.6%) tick. Further phylogenetic analysis of novel “Ca. Neoehrlichia”, Anaplasma and Ehrlichia based on 1,265 bp 16S rRNA gene sequences suggests that these are new species. Determining whether these newly discovered organisms cause disease in humans and animals, like closely related bacteria do abroad, is of public health importance and requires further investigation.

Inhibition of the endosymbiont "Candidatus Midichloria mitochondrii" during 16S rRNA gene profiling reveals potential pathogens in Ixodes ticks from Australia.

BackgroundThe Australian paralysis tick (Ixodes holocyclus) is of significant medical and veterinary importance as a cause of dermatological and neurological disease, yet there is currently limited information about the bacterial communities harboured by these ticks and the risk of infectious disease transmission to humans and domestic animals. Ongoing controversy about the presence of Borrelia burgdorferi sensu lato (the aetiological agent of Lyme disease) in Australia increases the need to accurately identify and characterise bacteria harboured by I. holocyclus ticks.MethodsUniversal PCR primers were used to amplify the V1-2 hyper-variable region of bacterial 16S rRNA genes present in DNA samples from I. holocyclus and I. ricinus ticks, collected in Australia and Germany respectively. The 16S amplicons were purified, sequenced on the Ion Torrent platform, and analysed in USEARCH, QIIME, and BLAST to assign genus and species-level taxonomy. Initial analysis of I. holocyclus and I. ricinus identified that > 95 % of the 16S sequences recovered belonged to the tick intracellular endosymbiont “Candidatus Midichloria mitochondrii” (CMM). A CMM-specific blocking primer was designed that decreased CMM sequences by approximately 96 % in both tick species and significantly increased the total detectable bacterial diversity, allowing identification of medically important bacterial pathogens that were previously masked by CMM.ResultsBorrelia burgdorferi sensu lato was identified in German I. ricinus, but not in Australian I. holocyclus ticks. However, bacteria of medical significance were detected in I. holocyclus ticks, including a Borrelia relapsing fever group sp., Bartonella henselae, novel “Candidatus Neoehrlichia” spp., Clostridium histolyticum, Rickettsia spp., and Leptospira inadai.ConclusionsAbundant bacterial endosymbionts, such as CMM, limit the effectiveness of next-generation 16S bacterial community profiling in arthropods by masking less abundant bacteria, including pathogens. Specific blocking primers that inhibit endosymbiont 16S amplification during PCR are an effective way of reducing this limitation. Here, this strategy provided the first evidence of a relapsing fever Borrelia sp. and of novel “Candidatus Neoehrlichia” spp. in Australia. Our results raise new questions about tick-borne pathogens in I. holocyclus ticks.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-015-0958-3) contains supplementary material, which is available to authorized users.

A randomized controlled trial of the efficacy of orally administered fluralaner (Bravecto™) against induced Ixodes holocyclus (Australian paralysis tick) infestations on dogs.

BackgroundIxodes holocyclus ticks are a frequently fatal threat to dogs in eastern Australia. These ticks secrete a neurotoxin that can produce an ascending paralysis after 72 h attachment that can lead to death in affected animals. Fluralaner is a potent systemic acaricide with immediate and persistent efficacy for tick control including evidence of 100% efficacy against Ixodes ricinus ticks within 72 h. This study investigated the potential for oral fluralaner administration to control I. holocyclus infestation and the subsequent risk of host paralysis.MethodsHealthy Foxhound and Foxhound cross dogs immunized against holocyclotoxin were randomly allocated to receive either a single fluralaner (at least 25 mg/kg) dose or no treatment. All dogs were penned individually and infested with 30 adult unfed female I. holocyclus 1 day before treatment and 14, 28, 42, 56, 70, 84, 112 and 140 days following treatment. Ticks were counted and assessed at 24, 48 and 72 h after the initial fluralaner treatment and after each subsequent infestation. Ticks were not removed at the 24 and 48 h assessments, but were removed after the 72 h assessments. On 112 and 140 days post treatment a new group of untreated control dogs was used.ResultsFluralaner treatment efficacy against I. holocyclus was 100% at 72 h post treatment. Following re-infestations the efficacy remained at 100% at the 72 h assessments for 115 days and reached 95.7% at 143 days. The differences between mean live tick counts on treatment and control groups were significant (P < 0.00l) at all assessment time points for 143 days following treatment.ConclusionsOral fluralaner treatment can prevent Australian paralysis tick infestations for at least 115 days.