Eimeria spp. infecting quenda (Isoodon obesulus) in the greater Perth region, Western Australia

Identification and genetic characterization of a novel species of Choleoeimeria Schneider, 1875 from a captive-bred bilby (Thylacomyidae; Macrotis lagotis) (Reid, 1837) in Western Australia

A novel Eimeria sp. from a captive-bred bilby (Macrotis lagotis Reid, 1837) has been identified in Western Australia. The bilby was bred at the Kanyana Wildlife Rehabilitation Centre, Perth, as part of the National Bilby Recovery Plan. Oocysts (n = 31) irregular blunt ellipsoidal, 17-18 × 11-12 (17.2 × 11.3); length/width (L/W) ratio 1.4-1.5 (1.5). Wall bi-layered, 0.8-1.0 (0.9) thick, outer layer smooth, c.2/3 of total thickness. Micropyle barely discernible. Oocyst residuum is absent, but 2-3 small polar granules are present. Sporocysts (n = 31) ovoidal, 7-8 × 5-6 (7.8 × 5.7); L/W ratio 1.3-1.4 (1.4). Stieda, sub-Stieda and para-Stieda bodies absent or indiscernible; sporocyst residuum present, usually as an irregular body consisting of numerous granules that appear to be membrane-bound or sometimes diffuse among sporozoites. Sporozoites vermiform with a robust refractile body. Further molecular characterization was conducted on the sporulated oocysts. At the 18S locus, it sat in a large clade of the phylogenetic tree with two isolates of Eimeria angustus from quendas (Isoodon obesulus Shaw, 1797) and the Choleoeimeria spp. It shared the highest identity with E. angustus (KU248093) at 98.84%; at the COI gene locus, it was unique and most closely related to Choleoeimeria taggarti, which is hosted by another species of marsupial, the yellow-footed antechinus (Antechinus flavipes flavipes), with 90.58% genetic similarity. Based on morphological and molecular data, this isolate is a new species and named as Choleoeimeria yangi n. sp.

Next-generation sequencing amplicon analysis of the genetic diversity of Eimeria populations in livestock and wildlife samples from Australia

Eimeria is an important coccidian enteric parasite that infects a wide range of hosts and can cause substantial economic losses in the poultry and livestock industries. It is common for multiple Eimeria species to infect individual hosts, and this can make species identification difficult due to morphological similarities between species and mixed chromatograms when using Sanger sequencing. Relatively few studies have applied next-generation amplicon sequencing (NGS) to determining the genetic diversity of Eimeria species in different hosts. The present study screened 408 faecal samples from a range of hosts including livestock and wildlife using a previously developed quantitative polymerase chain reaction (qPCR) at the 18S locus and conducted amplicon NGS on the positives using a ~ 455-bp fragment of the 18S locus. A total of 41 positives (10.1%) were identified by qPCR from various hosts and NGS was successful for 38 of these positives. Fifteen Eimeria species and three genotypes were detected by NGS: E. ferrisi, E. kanyana, E. potoroi, E. quokka, E. setonicis, E. trichosuri, E. reichenowi, E. angustus, E. ahsata, E. auburnensis, E. bovis, E. brasiliensis, E. christenseni, E. crandallis, E. ovinoidalis, Eimeria sp. (JF419345), Eimeria sp. (JF419349) and Eimeria sp. (JF419351). Mixed infections were detected in 55.3% (21/38) of positive samples. The most striking finding was the identification of the same species in different hosts. This could be due to contamination and/or mechanical transmission or may provide support for previous studies suggesting that Eimeria species can infect not just closely related hosts but different genera and further research is required. This is also the first study to audit Eimeria populations in livestock (sheep and cattle) by NGS and could be applied in the future to determine the extent of pathogenic species and outcomes of Eimeria control strategies.

Identification of a novel species of Eimeria Schneider, 1875 from the woylie, Bettongia penicillata Gray (Diprotodontia: Potoroidae) and the genetic characterisation of three Eimeria spp. from other potoroid marsupials

Faecal samples (n = 1,093) collected from the woylie Bettongia penicillata Gray, in south-western Australia were examined for the presence of coccidian parasites. Eimeria sp. oöcysts were detected in 15.2% of samples. Faecal samples obtained from the eastern bettong Bettongia gaimardi (Desmarest) (n = 4) and long-nosed potoroo Potorous tridactylus (Kerr) (n = 12) in Tasmania, were also screened for the presence of Eimeria spp. (prevalence 50% and 41.7%, respectively). Morphological and genetic comparison with other known species of Eimeria indicates that the material identified in woylies is novel. This study aimed to (i) morphologically describe and genetically characterise Eimeria woyliei n. sp. found in woylies; and (ii) genetically characterise Eimeria gaimardi Barker, O'Callaghan & Beveridge, 1988, Eimeria potoroi Barker, O'Callaghan & Beveridge, 1988, and Eimeria mundayi Barker, O'Callaghan & Beveridge, 1988, from other potoroid marsupials. Molecular phylogenetic analyses conducted at the 18S rDNA and mitochondrial cytochrome c oxidase subunit 1 (cox1) loci revealed that E. woyliei n. sp. was most closely related to Eimeria setonicis Barker, O'Callaghan & Beveridge, 1988, at the 18S rDNA locus, and Eimeria trichosuri O'Callaghan & O'Donoghue, 2001, at the cox1 locus. Eimeria woyliei n. sp. is the sixth species of Eimeria to be formally described from potoroid marsupials.

Co-immunization with two recombinant Eimeria tenella lines expressing immunoprotective antigens of E. maxima elicits enhanced protection against E. maxima infection

Background

Live anticoccidial vaccines have been a tremendous success for disease prevention. The establishment of the reverse genetic manipulation platform has enabled the development of Eimeria parasites, the live anticoccidial vaccine strains, as vaccine vectors. In our previous study, recombinant E. tenella expressing a single immunodominant antigen of E. maxima (Et-EmIMP1) was able to protect chickens against challenge infection with E. maxima. This promising result encouraged us to further explore strategies to improve the protection efficacy of recombinant Eimeria and develop it as a vaccine vector.

Results

We constructed a novel recombinant Eimeria line expressing apical membrane antigen 1 of E. maxima (Et-EmAMA1) and then immunized chickens with Et-EmAMA1 and/or Et-EmIMP1. We found that the E. maxima soluble antigen-specific cell-mediated immunity was much stronger in the birds that were co-immunized with Et-EmAMA1 and Et-EmIMP1 than in those that were immunized with Et-EmAMA1 or Et-EmIMP1 alone. The oocyst production after E. maxima infection was significantly reduced in the recombinant Eimeria-immunized birds compared with the wild-type-immunized and naïve birds. The oocyst production in the birds co-immunized with Et-EmAMA1 and Et-EmIMP1 was consistently the lowest among the treatment groups after E. maxima infection.

Conclusions

These results demonstrated that Eimeria is an effective vaccine vector that can carry and deliver heterologous Eimeria antigens to the host immune system and trigger specific immune responses. Our results also suggested that increasing the number of recombinant Eimeria lines is an effective approach to enhance protective immunity against infections with heterologous pathogens.

Anthropozoonotic significance, risk factors and spatial distribution of Giardia spp. infections in quenda (Isoodon obesulus) in the greater Perth region, Western Australia

Giardia spp. infections in wildlife populations have been linked to anthropogenic sources of infection and public health risk in a diversity of wildlife species and ecological locations worldwide. Quenda (Isoodon obesulus) remain in many urbanised areas of Perth, Western Australia, and can be gregarious in their interactions with humans and domestic animals. In a previous study, a high prevalence of Giardia spp. infection was identified amongst quenda trapped in urbanised environments and bushland in Perth, Western Australia. This study aimed to expand on that finding, by: identifying and estimating the prevalence of particular species of Giardia infecting quenda, and thus clarifying their anthropozoonotic/public health significance; identifying risk factors for Giardia spp. infection; and investigating putative associations between infection and indicators of ill health. Giardia spp. infections in Perth quenda are overwhelmingly of the host-adapted, non-zoonotic Giardia peramelis (apparent prevalence 22.2%; 95% CI 17.7–27.4%), indicating that quenda are not a substantial veterinary public health risk regarding this parasite genus. However, one case each of Giardia duodenalis and Giardia canis genotype D were identified in quenda trapped in urbanised environments (apparent prevalences 0.4%; 95% CI 0.1–1.9%). In quenda, Giardia spp. infection is associated with Cryptosporidium infection and flea infection intensity, which may reflect host population density, or regarding Cryptosporidium spp., similar transmission pathways or synergistic interactions between these taxa within the host. Giardia spp. infection is not associated with the measured indicators of ill health in Perth quenda, but this finding is representative of Giardia peramelis only, given the apparent rarity of other Giardia sp. infections in this study.

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Giardia spp. infections in Perth quenda are rarely of anthropozoonotic species.

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Anthropozoonotic Giardia spp. only found in quenda in urbanised environments.

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Quenda Giardia spp. infection risk is associated with Cryptosporidium spp.

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No association identified between G. peramelis infection and ill health indicators.

Urban environments alter parasite fauna, weight and reproductive activity in the quenda (Isoodon obesulus)

Some wildlife species are capable of surviving in urbanised environments. However, the implications of urbanisation on wildlife health, and public health regarding zoonoses, are often unknown. Quenda (syn. southern brown bandicoots, Isoodon obesulus) survive in many areas of Perth, Australia, despite urbanisation. This study investigated differences in gastrointestinal and macroscopic ecto-parasitic infections, morphometrics and reproductive status between bushland and urban dwelling quenda. 287 quenda in the greater Perth region were captured and sampled for faeces (to detect gastrointestinal parasites), blood (to detect Toxoplasma gondii antibodies), ectoparasites, and morphometrics. Data were analysed using multivariable logistic and linear regression. Most parasitic infections identified in quenda were of native parasite taxa that are either not known to, or considered highly unlikely to, infect humans or domestic animals. However, stickfast fleas (Echidnophaga spp.) were present at low prevalences and intensities, and Giardia spp., Cryptosporidium spp. and Amblyomma spp. infections require further investigation to clarify their anthropozoonotic significance. Quenda captured in urbanised environments had differing odds of or intensity of certain parasitic infections, compared to those in bushland - likely attributable to quenda population density, and in some cases the availability of other host species or anthropogenic sources of infection. Urbanised environments were associated with an increase in net weight of adult male quenda by 189.0g (95% CI 68.6-309.5g; p=0.002; adjusted R²=0.06) and adult female quenda by 140.1g (95% CI 3.9-276.3g; p=0.044; adjusted R²=0.07), with study findings suggesting a tendency towards obesity in urbanised environments. Adult female quenda in bushland had increased odds of an active pouch (adjusted OR=4.89, 95% CI 1.7-14.5), suggesting decreased reproductive activity in quenda from urbanised environments. These results highlight the subtle, yet extensive impacts that urbanised environments may have on wildlife ecology, even for those species which apparently adjust well to urbanisation.

A newly described strain of Eimeria arloingi (strain A) belongs to the phylogenetic group of ruminant-infecting pathogenic species, which replicate in host endothelial cells in vivo

Coccidiosis caused by Eimeria species is an important disease worldwide, particularly in ruminants and poultry. Eimeria infection can result in significant economic losses due to costs associated with treatment and slower growth rates, or even with mortality of heavily infected individuals. In goat production, a growing industry due to increasing demand for caprine products worldwide, coccidiosis is caused by several Eimeria species with E. arloingi and E. ninakohlyakimovae the most pathogenic. The aims of this study were genetic characterization of a newly isolated European E. arloingi strain (A) and determination of phylogenetic relationships with Eimeria species from other ruminants. Therefore, a DNA sequence of E. arloingi strain (A) containing 2290 consensus nucleotides (the majority of 18S rDNA, complete ITS-1 and 5.8S sequences, and the partial ITS-2) was amplified and phylogenetic relationship determined with the most similar sequences available on GenBank. The phylogenetic tree presented a branch constituted by bovine Eimeria species plus E. arloingi, and another one exclusively populated by ovine Eimeria species. Moreover, E. arloingi, E. bovis and E. zuernii, which all replicate in host intestinal endothelial cells of the lacteals, were found within the same cluster. This study gives new insights into the evolutionary phylogenetic relationships of this newly described caprine Eimeria strain and confirmed its close relationship to other highly pathogenic ruminant Eimeria species characterized by macromeront formation in host endothelial cells of the central lymph capillaries of the small intestine.