Trypanosoma melophagium from the sheep ked Melophagus ovinus on the island of St Kilda

Molecular pathogen screening of louse flies (Diptera: Hippoboscidae) from domestic and wild ruminants in Austria

BACKGROUND

Hippoboscid flies (Diptera: Hippoboscidae), also known as louse flies or keds, are obligate blood-sucking ectoparasites of animals, and accidentally of humans. The potential role of hippoboscids as vectors of human and veterinary pathogens is being increasingly investigated, but the presence and distribution of infectious agents in louse flies is still unknown in parts of Europe. Here, we report the use of molecular genetics to detect and characterize vector-borne pathogens in hippoboscid flies infesting domestic and wild animals in Austria.

METHODS

Louse flies were collected from naturally infested cattle (n = 25), sheep (n = 3), and red deer (n = 12) across Austria between 2015 and 2019. Individual insects were morphologically identified to species level and subjected to DNA extraction for molecular pathogen screening and barcoding. Genomic DNA from each louse fly was screened for Borrelia spp., Bartonella spp., Trypanosomatida, Anaplasmataceae, Filarioidea and Piroplasmida. Obtained sequences of Trypanosomatida and Bartonella spp. were further characterized by phylogenetic and haplotype networking analyses.

RESULTS

A total of 282 hippoboscid flies corresponding to three species were identified: Hippobosca equina (n = 62) collected from cattle, Melophagus ovinus (n = 100) from sheep and Lipoptena cervi (n = 120) from red deer (Cervus elaphus). Molecular screening revealed pathogen DNA in 54.3% of hippoboscids, including infections with single (63.39%), two (30.71%) and up to three (5.90%) distinct pathogens in the same individual. Bartonella DNA was detected in 36.9% of the louse flies. Lipoptena cervi were infected with 10 distinct and previously unreported Bartonella sp. haplotypes, some closely associated with strains of zoonotic potential. DNA of trypanosomatids was identified in 34% of hippoboscids, including the first description of Trypanosoma sp. in H. equina. Anaplasmataceae DNA (Wolbachia spp.) was detected only in M. ovinus (16%), while < 1% of the louse flies were positive for Borrelia spp. and Filarioidea. All hippoboscids were negative for Piroplasmida.

CONCLUSIONS

Molecular genetic screening confirmed the presence of several pathogens in hippoboscids infesting domestic and wild ruminants in Austria, including novel pathogen haplotypes of zoonotic potential (e.g. Bartonella spp.) and the first report of Trypanosoma sp. in H. equina, suggesting a potential role of this louse fly as vector of animal trypanosomatids. Experimental transmission studies and expanded monitoring of hippoboscid flies and hippoboscid-associated pathogens are warranted to clarify the competence of these ectoparasites as vectors of infectious agents in a One-Health context.

The genome of sheep ked (Melophagus ovinus) reveals potential mechanisms underlying reproduction and narrower ecological niches

BACKGROUND

Melophagus ovinus is considered to be of great veterinary health significance. However, little is known about the information on genetic mechanisms of the specific biological characteristics and novel methods for controlling M. ovinus.

RESULTS

In total, the de novo genome assembly of M. ovinus was 188.421 Mb in size (330 scaffolds, N50 Length: 10.666 Mb), with a mean GC content of 27.74%. A total of 13,372 protein-coding genes were functionally annotated. Phylogenetic analysis indicated that the diversification of M. ovinus and Glossina fuscipes took place 72.76 Mya within the Late Cretaceous. Gene family expansion and contraction analysis revealed that M. ovinus has 65 rapidly-evolving families (26 expansion and 39 contractions) mainly involved DNA metabolic activity, transposases activity, odorant receptor 59a/67d-like, IMD domain-containing protein, and cuticle protein, etc. The universal and tightly conserved list of milk protein orthologues has been assembled from the genome of M. ovinus. Contractions and losses of sensory receptors and vision-associated Rhodopsin genes were significant in M. ovinus, which indicate that the M. ovinus has narrower ecological niches.

CONCLUSIONS

We sequenced, assembled, and annotated the whole genome sequence of M. ovinus, and launches into the preliminary genetic mechanisms analysis of the adaptive evolution characteristics of M. ovinus. These resources will provide insights to understand the biological underpinnings of this parasite and the disease control strategies.

First determination of DNA virus and some additional bacteria from Melophagus ovinus (sheep ked) in Tibet, China

Melophagus ovinus (sheep ked) is one of the common ectoparasites in sheep. In addition to causing direct damage to the host through biting and sucking blood, sheep ked is a potential vector of helminths, protozoa, bacteria, and viruses. Sheep M. ovinus samples from three regions in Tibet were selected for DNA extraction. The 16S rDNA V3-V4 hypervariable region was amplified, after genomic DNA fragmentation, Illumina Hiseq libraries were constructed. The 16S rRNA sequencing and viral metagenomics sequencing were separately conducted on the Illumina Novaseq 6000 platform and molecular biology software and platforms were employed to analyze the sequencing data. Illumina PE250 sequencing results demonstrated that the dominant bacteria phylum in M. ovinus from Tibet, China was Proteobacteria, where 29 bacteria genera were annotated. The dominant bacterial genera were Bartonella, Wolbachia, and Arsenophonus; Bartonella chomelii, Wolbachia spp., and Arsenophonus spp. were the dominant bacterial species in M. ovinus from Tibet, China. We also detected Kluyvera intermedia, Corynebacterium maris DSM 45190, Planomicrobium okeanokoites, and Rhodococcus erythropolis, of which the relative abundance of Kluyvera intermedia was high. Illumina Hiseq sequencing results demonstrated that 4 virus orders were detected in M. ovinus from Tibet, China, and 3 samples were annotated into 29 families, 30 families, and 28 families of viruses, respectively. Virus families related to vertebrates and insects mainly included Mimiviridae, Marseilleviridae, Poxviridae, Ascoviridae, Iridoviridae, Baculoviridae, Hytrosaviridae, Nudiviridae, Polydnaviridae, Adomaviridae, Asfarviridae, Hepeviridae, Herpesviridae, and Retroviridae; at the species level, the relative abundance of Tupanvirus_soda_lake, Klosneuvirus_KNV1, and Indivirus_ILV1 was higher. African swine fever virus and many poxviruses from the family Poxviridae were detected, albeit their relative abundance was low. The dominant bacterial phylum of M. ovinus from Tibet, China was Proteobacteria, and the dominant bacterial genera were Bartonella, Wolbachia, and Arsenophonus, where 23 out of 29 annotated bacteria genera were first reported in M. ovinus. Kluyvera intermedia, Corynebacterium maris DSM 45190, Planomicrobium okeanokoites, and Rhodococcus erythropolis were detected for the first time. All DNA viruses detected in this study have been reported in M. ovinus for the first time.

Tandem mass tag labeled quantitative proteomic analysis of differential protein expression on total alkaloid of Aconitum flavum Hand.-Mazz. against melophagus ovinus

Melophagus ovinus disease is a common ectoparasitosis, which can lead to a decrease in animal production performance, product quality, and even death. Aconitum flavum Hand.-Mazz. has many pharmacological activities including insecticidal, heat-clearing, analgesic, and dehumidifying. However, there are few researches focused on the effects and related mechanism of Aconitum flavum Hand.-Mazz. in killing Melophagus ovinus. In this study, 11 alkaloids of Aconitum flavum Hand.-Mazz. were detected, and its total alkaloid activity was determined. The results showed when the total alkaloid concentration was 64 mg/ml and the treatment time was 16 h, the killing rate of Melophagus ovinus reached 100%. Through the observation of the differences in the surface of Melophagus ovinus in each experimental group, it was found that the morphology of the posterior end of the female Melophagus ovinus in the alkaloid treatment group was significantly different from that of the blank and positive control groups, and most of the epidermal tissue was obsessive and missing. Moreover, the enzyme activity determination results of 64 mg/ml group were significantly different when compared with the normal control group, while there was no significant difference in other groups. Then, the Melophagus ovinus gene library was established by the unreferenced genome transcriptome sequencing, the proteomic comparison was performed using tandem mass tag labeled protein detection technology, and finally, the samples were quantitatively analyzed by liquid chromatography-mass spectrometry tandem and bioinformatics methods. Based on the above experimental results, it was speculated that Aconitum flavum Hand.-Mazz. total alkaloids may cause the imbalance of protein disulfide isomerase expressions by affecting the regulation of Hsp40 cellular protein homeostasis and the oxidation of protein disulfide isomerase and related proteins. This would affect the selective recognition of signal sequence, the targeted transport of Sec 61, and the correct folding of the three-dimensional structure of amino acid chain, weakening the clearance of amino acid chains that cannot be correctly folded and eventually resulting in the killing of Melophagus ovinus. This study preliminarily revealed the mechanism of Aconitum flavum Hand.-Mazz. total alkaloids against Melophagus ovinus and provided a theoretical basis for the screening of Melophagus ovinus action targets and the development of new veterinary drugs.

The genomic basis of host and vector specificity in non-pathogenic trypanosomatids

Trypanosoma theileri, a non-pathogenic parasite of bovines, has a predicted surface protein architecture that likely aids survival in its mammalian host. Their surface proteins are encoded by genes which account for ∼10% of their genome. A non-pathogenic parasite of sheep, Trypanosoma melophagium, is transmitted by the sheep ked and is closely related to T. theileri. To explore host and vector specificity between these species, we sequenced the T. melophagium genome and transcriptome and an annotated draft genome was assembled. T. melophagium was compared to 43 kinetoplastid genomes, including T. theileri. T. melophagium and T. theileri have an AT biased genome, the greatest bias of publicly available trypanosomatids. This trend may result from selection acting to decrease the genomic nucleotide cost. The T. melophagium genome is 6.3Mb smaller than T. theileri and large families of proteins, characteristic of the predicted surface of T. theileri, were found to be absent or greatly reduced in T. melophagium. Instead, T. melophagium has modestly expanded protein families associated with the avoidance of complement-mediated lysis. We propose that the contrasting genomic features of these species is linked to their mode of transmission from their insect vector to their mammalian host. This article has an associated First Person interview with the first author of the paper.

Trypanosomes of the Trypanosoma theileri Group: Phylogeny and New Potential Vectors

Trypanosomes belonging to Trypanosoma theileri group are mammalian blood parasites with keds and horse fly vectors. Our aim is to study to vector specificity of T. theileri trypanosomes. During our bloodsucking Diptera survey, we found a surprisingly high prevalence of T. theileri trypanosomes in mosquitoes (154/4051). Using PCR and gut dissections, we detected trypanosomes of T. theileri group mainly in Aedes mosquitoes, with the highest prevalence in Ae. excrucians (22%), Ae. punctor (21%), and Ae. cantans/annulipes (10%). Moreover, T. theileri group were found in keds and blackflies, which were reported as potential vectors for the first time. The vectorial capacity was confirmed by experimental infections of Ae. aegypti using our isolates from mosquitoes; sand fly Phlebotomus perniciosus supported the development of trypanosomes as well. Infection rates were high in both vectors (47–91% in mosquitoes, 65% in sandflies). Furthermore, metacyclic stages of T. theileri trypanosomes were observed in the gut of infected vectors; these putative infectious forms were found in the urine of Ae. aegypti after a second bloodmeal. On the contrary, Culex pipiens quinquefasciatus was refractory to experimental infections. According to a phylogenetic analysis of the 18S rRNA gene, our trypanosomes belong into three lineages, TthI, ThII, and a lineage referred to as here a putative lineage TthIII. The TthI lineage is transmitted by Brachycera, while TthII and ThIII include trypanosomes from Nematocera. In conclusion, we show that T. theileri trypanosomes have a wide range of potential dipteran vectors, and mosquitoes and, possibly, sandflies serve as important vectors.

Genetic diversity of cervid Trypanosoma theileri in Honshu sika deer (Cervus nippon) in Japan

The taxonomy of ruminant Trypanosoma theileri and its relatives (Kinetoplastida: Trypanosomatidae) is controversial, with recent phylogenetic studies segregating T. theileri in cattle and other ruminants worldwide into two major genetic lineages (the TthI and TthII clades) based on genetic markers. In the present study, T. theileri-like trypanosomes isolated from Honshu sika deer (Cervus nippon) in the western Japan (YMG isolate) were genetically characterized using a number of genetic markers. Sika deer trypanosomes of the YMG isolate were genetically different from the Trypanosoma sp. TSD1 isolate previously recorded from Hokkaido sika deer in northern Japan, with the former trypanosome isolate being genetically closer to European cervid trypanosomes and the bovine T. theileri TthII lineage. In contrast, the latter isolate exhibited greater relatedness to North American cervid trypanosomes and the bovine T. theileri TthI lineage, although a clear genetic distinction between these was apparent. Furthermore, trypanosomes in Honshu sika deer from the central part of Japan harboured additional genetic diversity and were closer to either TSD1 or YMG isolates, while distinct from known T. theileri-related genotypes. Importantly, cervids and wild ruminants worldwide might harbour divergent descendants of a T. theileri ancestor, which exhibit rigid host specificity to either bovines or cervid species.

Major Causes of Calf and Lamb Mortality and Morbidity and Associated Risk Factors in the Mixed Crop-Livestock Production System in Jamma District, South Wollo, Ethiopia

Lamb and calf preweaning mortality and morbidity account for serious losses in sheep and cattle production and are, thus, a major factor in reducing profitability and adversely affecting the sheep and cattle farming. Thus, a prospective cohort study was conducted in Jamma district, Amhara Regional State, to determine the major cause of calf and lamb morbidity and mortality and associated risk factors. A semi-structured questionnaire and clinical assessment of the animals were conducted from 150 households to assess the potential risk factors. Besides, a total of 102 (81 fecal samples and 21 skin scrapings) were collected from 150 clinically ill and suspected animals to identify the cause of morbidity and mortality. The test of difference and correlation between variables were computed using chi-square and generalized linear model analysis. The total morbidity and mortality in calves were 33.3% and 2%, respectively, whereas for lamb, they were 27.3% and 32.5%, respectively. In calf, septicemia (100%) was a major cause of mortality, and diarrhea (54.6%) was the leading cause of calf morbidity followed by skin disease (30.1%), respiratory problems (12%), and septicemia (3.3%). Malnutrition was the most common problem in lambs causing up to 31.3% mortality followed by diarrhea 24% and respiratory problems 21.3%. The presence of a disease in adult cattle was significantly correlated to the presence of disease in calves (p < 0.001; r = 0.35). There was also a significantly higher positive correlation between sickness in adult sheep and lambs (p < 0.001, r = 0.45). Gastrointestinal parasitosis was identified in 82.7% of the samples collected from diarrheic and suspected calves (87.1% positive) and lambs (80% positive). Monezia species in lamb (33.3%) and Coccidia species in the calf (35.9%) had the largest morbidity rate. Ctenocephalides canis (16.7%) and Linognatus species (41.7%) were common ectoparasites identified in calves, while Melophagus ovinus was the only ectoparasite of lambs recovered (62.5%). In conclusion, the high morbidity found in calves and morbidity and mortality in lambs are known to seriously reduce the profitability of the smallholder cattle and sheep production in the area by affecting the availability of replacement animals and causing a detrimental effect on herd expansion and productivity. In further studies, establishing the specific causative agents, control of diseases in the adult, and improvement in feed resources should be the major areas that need to be considered to mitigate calf and lamb morbidity and mortality currently affecting the area.

The role of sheep ked (Melophagus ovinus) as potential vector of protozoa and bacterial pathogens

The sheep ked (Melophagus ovinus) hematophagous insect may act as a potential vector of vector-borne pathogens. The aim of this study was to detect the presence of Trypanosoma spp., Bartonella spp., Anaplasma phagocytophilum and Borrelia burgdorferi sensu lato in sheep ked collected from sheep in Poland. In total, Trypanosoma spp. was detected in 58.91% of M. ovinus, whereas Bartonella spp. and B. burgdorferi s.l. were found in 86.82% and 1.55% of the studied insects, respectively. A. phagocytophilum was not detected in the studied material. In turn, co-infection by Trypanosoma spp. and Bartonella spp. was detected in 50.39%, while co-infection with Trypanosoma spp. and Bartonella spp. and B. burgdorferi s.l. was found in 1.55% of the studied insects. The conducted study showed for the first time the presence of B. burgdorferi s. l. in M. ovinus, as well as for the first time in Poland the presence of Trypanosoma spp. and Bartonella spp. The obtained results suggest that these insects may be a potential vector for these pathogens, but further-more detailed studies are required.

Autochthonous Trypanosoma spp. in European Mammals: A Brief Journey amongst the Neglected Trypanosomes

The genus Trypanosoma includes flagellated protozoa belonging to the family Trypanosomatidae (Euglenozoa, Kinetoplastida) that can infect humans and several animal species. The most studied species are those causing severe human pathology, such as Chagas disease in South and Central America, and the human African trypanosomiasis (HAT), or infections highly affecting animal health, such as nagana in Africa and surra with a wider geographical distribution. The presence of these Trypanosoma species in Europe has been thus far linked only to travel/immigration history of the human patients or introduction of infected animals. On the contrary, little is known about the epidemiological status of trypanosomes endemically infecting mammals in Europe, such as Trypanosomatheileri in ruminants and Trypanosomalewisi in rodents and other sporadically reported species. This brief review provides an updated collection of scientific data on the presence of autochthonous Trypanosoma spp. in mammals on the European territory, in order to support epidemiological and diagnostic studies on Trypanosomatid parasites.

Detection of Theileria spp. in ticks, sheep keds (Melophagus ovinus), and livestock in the eastern Tibetan Plateau, China

Theileria species, with a broad geographic distribution, infect a wide range of both domestic and wild animals and are transmitted by ixodid ticks. Currently, there is no comprehensive report regarding the distribution of Theileria spp. in the eastern Tibetan Plateau, especially in Ganze Tibetan autonomous prefecture (153,700 km²) and Ngawa Tibetan and Qiang autonomous prefecture (84,242 km²) of Sichuan province, China. In this study, we collected blood samples from yaks (n = 144) (Bos grunniens), Tibetan sheep (n = 92), and Tibet horses (n = 142) in Ganze and Ngawa.Theileria sinensis, T. luwenshuni, and T. equi were the dominant Theileria species detected in yaks, Tibetan sheep, and horses with the total infection rates of 25.7% (37/144), 75.0% (69/92), and 51.4% (73/142), respectively. For ectoparasites, T. luwenshuni was the only Theileria species detected in sheep keds (Melophagus ovinus) with an infection rate of 30.8% (8/26). The total infection rates of T. sinensis in Haemaphysalis qinghaiensis, Dermacentor everestianus, and Rhipicephalus microplus were 34.6% (36/104), 34.0% (17/50), and 51.3% (58/113), respectively. Theileria spp., belonging to T. sergenti/buffeli/orientalis group, were only detected in R. microplus collected in Danba county of Ganze with a total infection rate of 39.9% (19/48). Our results provide important data of the epidemiology of Theileria spp. in livestock and ectoparasites and will assist with the implementation of measures to control theileriosis transmission in eastern Tibetan Plateau, China.

Pan-American Trypanosoma (Megatrypanum) trinaperronei n. sp. in the white-tailed deer Odocoileus virginianus Zimmermann and its deer ked Lipoptena mazamae Rondani, 1878: morphological, developmental and phylogeographical characterisation

BACKGROUND

The subgenus Megatrypanum Hoare, 1964 of Trypanosoma Gruby, 1843 comprises trypanosomes of cervids and bovids from around the world. Here, the white-tailed deer Odocoileus virginianus (Zimmermann) and its ectoparasite, the deer ked Lipoptena mazamae Rondani, 1878 (hippoboscid fly), were surveyed for trypanosomes in Venezuela.

RESULTS

Haemoculturing unveiled 20% infected WTD, while 47% (7/15) of blood samples and 38% (11/29) of ked guts tested positive for the Megatrypanum-specific TthCATL-PCR. CATL and SSU rRNA sequences uncovered a single species of trypanosome. Phylogeny based on SSU rRNA and gGAPDH sequences tightly cluster WTD trypanosomes from Venezuela and the USA, which were strongly supported as geographical variants of the herein described Trypanosoma (Megatrypanum) trinaperronei n. sp. In our analyses, the new species was closest to Trypanosoma sp. D30 from fallow deer (Germany), both nested into TthII alongside other trypanosomes from cervids (North American elk and European fallow, red and sika deer), and bovids (cattle, antelopes and sheep). Insights into the life-cycle of T. trinaperronei n. sp. were obtained from early haemocultures of deer blood and co-culture with mammalian and insect cells showing flagellates resembling Megatrypanum trypanosomes previously reported in deer blood, and deer ked guts. For the first time, a trypanosome from a cervid was cultured and phylogenetically and morphologically (light and electron microscopy) characterised.

CONCLUSIONS

In the analyses based on SSU rRNA, gGAPDH, CATL and ITS rDNA sequences, neither cervids nor bovids trypanosomes were monophyletic but intertwined within TthI and TthII major phylogenetic lineages. One host species can harbour more than one species/genotype of trypanosome, but each trypanosome species/genotype was found in a single host species or in phylogenetically closely related hosts. Molecular evidence that L. mazamae may transmit T. trinaperronei n. sp. suggests important evolutionary constraints making tight the tripartite T. trinaperronei-WTD-deer ked association. In a plausible evolutionary scenario, T. trinaperronei n. sp. entered South America with North American white-tailed deer at the Pliocene-Pleistocene boundary following the closure of the Panama Isthmus.

Detection of blood pathogens in camels and their associated ectoparasitic camel biting keds, Hippobosca camelina: the potential application of keds in xenodiagnosis of camel haemopathogens

Background: Major constraints to camel production include pests and diseases. In northern Kenya, little information is available about blood-borne pathogens circulating in one-humped camels ( Camelus dromedarius) or their possible transmission by the camel haematophagous ectoparasite, Hippobosca camelina, commonly known as camel ked or camel fly. This study aimed to: (i) identify the presence of potentially insect-vectored pathogens in camels and camel keds, and (ii) assess the potential utility of keds for xenodiagnosis of camel pathogens that they may not vector.

Methods: In Laisamis, northern Kenya, camel blood samples (n = 249) and camel keds (n = 117) were randomly collected from camels. All samples were screened for trypanosomal and camelpox DNA by PCR, and for Anaplasma, Ehrlichia, Brucella, Coxiella, Theileria, and Babesia by PCR coupled with high-resolution melting (PCR-HRM) analysis.

Results: In camels, we detected Trypanosoma vivax (41%), Trypanosoma evansi (1.2%), and “ Candidatus Anaplasma camelii” (68.67%). In camel keds, we also detected T. vivax (45.3%), T. evansi (2.56%), Trypanosoma melophagium (1/117) (0.4%), and “ Candidatus Anaplasma camelii” (16.24 %). Piroplasms ( Theileria spp. and Babesia spp.), Coxiella burnetii, Brucella spp., Ehrlichia spp., and camel pox were not detected in any samples.

Conclusions: This study reveals the presence of epizootic pathogens in camels from northern Kenya. Furthermore, the presence of the same pathogens in camels and in keds collected from sampled camels suggests the potential use of these flies in xenodiagnosis of haemopathogens circulating in camels.

Detection of blood pathogens in camels and their associated ectoparasitic camel biting keds, Hippobosca camelina: the potential application of keds in xenodiagnosis of camel haemopathogens

Background: Major constraints to camel production include pests and diseases. In northern Kenya, little information is available about blood-borne pathogens circulating in one-humped camels ( Camelus dromedarius) or their possible transmission by the camel haematophagous ectoparasite, Hippobosca camelina, commonly known as camel ked or camel fly. This study aimed to: (i) identify the presence of potentially insect-vectored pathogens in camels and camel keds, and (ii) assess the potential utility of keds for xenodiagnosis of camel pathogens that they may not vector. Methods: In Laisamis, northern Kenya, camel blood samples (n = 249) and camel keds (n = 117) were randomly collected from camels. All samples were screened for trypanosomal and camelpox DNA by PCR, and for Anaplasma, Ehrlichia, Brucella, Coxiella, Theileria, and Babesia by PCR coupled with high-resolution melting (PCR-HRM) analysis. Results: In camels, we detected Trypanosoma vivax (41%), Trypanosoma evansi (1.2%), and " Candidatus Anaplasma camelii" (68.67%). In camel keds, we also detected T. vivax (45.3%), T. evansi (2.56%), Trypanosoma melophagium (1/117) (0.4%), and " Candidatus Anaplasma camelii" (16.24 %). Piroplasms ( Theileria spp. and Babesia spp.), Coxiella burnetii, Brucella spp., Ehrlichia spp., and camel pox were not detected in any samples. Conclusions: This study reveals the presence of epizootic pathogens in camels from northern Kenya. Furthermore, the presence of the same pathogens in camels and in keds collected from sampled camels suggests the potential use of these flies in xenodiagnosis of haemopathogens circulating in camels.

Theileria ovis (Piroplasmida: Theileriidae) Detected in Melophagus ovinus (Diptera: Hippoboscoidea) and Ornithodoros lahorensis (Ixodida: Argasidae) Removed From Sheep in Xinjiang, China

Theileria spp. are tick-transmitted, intracellular apicomplexan protozoan parasites that infect a wide range of animals and, as such, can cause significant economic losses. The aim of the present study was to detect and analyze apicomplexan parasites from two different ectoparasites that were collected from Xinjiang Uygur Autonomous Region, China. The PCR-based detection of 18S rRNA indicated that Ornithodoros lahorensis specimens from Kashgar, Xinjiang, and Aksu were positive for Theileria spp., as were Melophagus ovinus specimens from Aksu. Meanwhile, phylogenetic analysis, based on the 18S rRNA gene sequences, revealed that the four amplified Theileria sequences could be attributed to T. ovis. To the best of our knowledge, this is the first study to report the detection of T. ovis DNA in M. ovinus and the first molecular identification study to confirm the detection of T. ovis in O. lahorensis in China. Accordingly, the present study extends the known distribution of T. ovis.

Molecular Identification of Bartonella melophagi and Wolbachia Supergroup F from Sheep Keds in Xinjiang, China

To confirm that Bartonella and Wolbachia were carried by sheep keds (Melophagus ovinus) in southern Xinjiang of China, 17 M. ovinus samples, which were collected in Aksu Prefecture, Xinjiang, were randomly selected. In this study, the Bartonella gltA and Wolbachia 16S rRNA gene were amplified through conventional PCR and the sequence of those amplified products, were analyzed. The results demonstrated that Bartonella was carried by all of the 17 sheep keds and Wolbachia was carried by 15 out of them. Bartonella was identified as B. melophagi. Three strains of Wolbachia were supergroup F and 1 strain has not been confirmed yet. It is the first report about Wolbachia supergroup F was found in sheep keds and provided the molecular evidence that B. melophagi and Wolbachia supergroup F were carried by sheep keds in Aksu Prefecture of southern Xinjiang, China. The 2 pathogens were found in sheep keds around Taklimakan Desert for the first time.

An Alternative Strategy for Trypanosome Survival in the Mammalian Bloodstream Revealed through Genome and Transcriptome Analysis of the Ubiquitous Bovine Parasite Trypanosoma (Megatrypanum) theileri

There are hundreds of Trypanosoma species that live in the blood and tissue spaces of their vertebrate hosts. The vast majority of these do not have the ornate system of antigenic variation that has evolved in the small number of African trypanosome species, but can still maintain long-term infections in the face of the vertebrate adaptive immune system. Trypanosoma theileri is a typical example, has a restricted host range of cattle and other Bovinae, and is only occasionally reported to cause patent disease although no systematic survey of the effect of infection on agricultural productivity has been performed. Here, a detailed genome sequence and a transcriptome analysis of gene expression in bloodstream form T. theileri have been performed. Analysis of the genome sequence and expression showed that T. theileri has a typical kinetoplastid genome structure and allowed a prediction that it is capable of meiotic exchange, gene silencing via RNA interference and, potentially, density-dependent growth control. In particular, the transcriptome analysis has allowed a comparison of two distinct trypanosome cell surfaces, T. brucei and T. theileri, that have each evolved to enable the maintenance of a long-term extracellular infection in cattle. The T. theileri cell surface can be modeled to contain a mixture of proteins encoded by four novel large and divergent gene families and by members of a major surface protease gene family. This surface composition is distinct from the uniform variant surface glycoprotein coat on African trypanosomes providing an insight into a second mechanism used by trypanosome species that proliferate in an extracellular milieu in vertebrate hosts to avoid the adaptive immune response.

First report of Anaplasma ovis in pupal and adult Melophagus ovinus (sheep ked) collected in South Xinjiang, China

Background

Melophagus ovinus (sheep ked) is a blood-feeding ectoparasite that belongs to the family Hippoboscidae (Diptera: Hippoboscoidea) and mainly parasitizes sheep. The life-cycle of M. ovinus consists of three stages: larva, pupa and adult. It has a worldwide distribution and has been found in four provinces of China, especially South Xinjiang. In addition to causing direct damage to animal hosts, M. ovinus serves as a vector for disease transmission. In this study, our aim was to investigate the presence of Anaplasma spp. in pupal and adult M. ovinus.

Methods

A total of 93 specimens (including eight pupal specimens) of M. ovinus collected in South Xinjiang were selected for isolation of genomic DNA, followed by PCR amplification and sequencing of the msp4 gene of Anaplasma spp. The sequences were analyzed in MEGA 7.0 software and via online BLAST.

Results

PCR and sequencing results showed that all the specimens collected in 2013 were free of Anaplasma spp., whereas three and 25 specimens (including five pupal specimens) collected in 2016 and 2017, respectively, tested positive for Anaplasma spp. The analysis of 24 msp4 gene sequences (from four pupal specimens) confirmed the presence of A. ovis in M. ovinus specimens collected in South Xinjiang, China. The detected A. ovis isolates belong to Genotypes II and III.

Conclusions

To the best of our knowledge, this is the first report of the detection of A. ovis DNA in pupal M. ovinus, confirming the vertical transmission of A. ovis in M. ovinus and the potential of M. ovinus to serve as a vector for A. ovis.

Microbial population analysis of the midgut of Melophagus ovinus via high-throughput sequencing

Background

Melophagus ovinus, one of the most common haematophagous ectoparasites of sheep, can cause anaemia and reductions in weight gain, wool growth and hide value. However, no information is available about the microfloral structure of the midgut of this ectoparasite. In the present study, we investigated the microbial community structure of the midgut contents of fully engorged female and male M. ovinus using Illumina HiSeq.

Results

The phylum showing the highest abundance was Proteobacteria (99.9%). The dominant bacterial genera in females and males were Bartonella, Arsenophonus and Wolbachia. Some less abundant bacterial genera were also detected, including Enterobacter, Acinetobacter, Halomonas, Shewanella, Bacillus and Staphylococcus.

Conclusions

Bartonella, Arsenophonus and Wolbachia were the dominant bacterial genera in the midgut of female and male M. ovinus. Although detected, Enterobacter, Acinetobacter, Halomonas, Shewanella, Bacillus and Staphylococcus showed low abundances. Importantly, this is the first report of the presence of Arsenophonus, Wolbachia, Enterobacter, Halomonas, Shewanella, Bacillus and Staphylococcus in the midgut of M. ovinus.

First report of Rickettsia raoultii and R. slovaca in Melophagus ovinus, the sheep ked

BACKGROUND

Melophagus ovinus (Diptera: Hippoboscidae), a hematophagous ectoparasite, is mainly found in Europe, Northwestern Africa, and Asia. This wingless fly infests sheep, rabbits, and red foxes, and causes inflammation, wool loss and skin damage. Furthermore, this parasite has been shown to transmit diseases, and plays a role as a vector. Herein, we investigated the presence of various Rickettsia species in M. ovinus.

METHODS

In this study, a total of 95 sheep keds were collected in Kuqa County and Alaer City southern region of Xinjiang Uygur Autonomous Region, northwestern China. First, collected sheep keds were identified on the species level using morphological keys and molecular methods based on a fragment of the 18S ribosomal DNA gene (18S rDNA). Thereafter, to assess the presence of rickettsial DNA in sheep keds, the DNA of individual samples was screened by PCR based on six Rickettsia-specific gene fragments originating from six genes: the 17-kilodalton antigen gene (17-kDa), 16S rRNA gene (rrs), surface cell antigen 4 gene (sca4), citrate synthase gene (gltA), and outer membrane protein A and B genes (ompA and ompB). The amplified products were confirmed by sequencing and BLAST analysis ( https://blast.ncbi.nlm.nih.gov/Blast.cgi?PROGRAM=blastn&PAGE_TYPE=BlastSearch&LINK_LOC=blasthome ).

RESULTS

According to its morphology and results of molecular analysis, the species was identified as Melophagus ovinus, with 100% identity to M. ovinus from St. Kilda, Australia (FN666411). DNA of Rickettsia spp. were found in 12 M. ovinus samples (12.63%, 12/95). Rickettsia raoultii and R. slovaca were confirmed based on phylogenetic analysis, although the genetic markers of these two rickettsial agents amplified in this study showed molecular diversity.

CONCLUSIONS

This is the first report of R. raoultii and R. slovaca DNA in M. ovinus. Rickettsia slovaca was found for the first time around the Taklimakan Desert located in China. This finding extends the geographical range of spotted fever group rickettsiae.

Exposure to viral and bacterial pathogens among Soay sheep (Ovis aries) of the St Kilda archipelago

We assessed evidence of exposure to viruses and bacteria in an unmanaged and long-isolated population of Soay sheep (Ovis aries) inhabiting Hirta, in the St Kilda archipelago, 65 km west of Benbecula in the Outer Hebrides of Scotland. The sheep harbour many metazoan and protozoan parasites but their exposure to viral and bacterial pathogens is unknown. We tested for herpes viral DNA in leucocytes and found that 21 of 42 tested sheep were infected with ovine herpesvirus 2 (OHV-2). We also tested 750 plasma samples collected between 1997 and 2010 for evidence of exposure to seven other viral and bacterial agents common in domestic Scottish sheep. We found evidence of exposure to Leptospira spp., with overall seroprevalence of 6·5%. However, serological evidence indicated that the population had not been exposed to border disease, parainfluenza, maedi-visna, or orf viruses, nor to Chlamydia abortus. Some sheep tested positive for antibodies against Mycobacterium avium subsp. paratuberculosis (MAP) but, in the absence of retrospective faecal samples, the presence of this infection could not be confirmed. The roles of importation, the pathogen-host interaction, nematode co-infection and local transmission warrant future investigation, to elucidate the transmission ecology and fitness effects of the few viral and bacterial pathogens on Hirta.

Epidemiology of Trypanosoma evansi and Trypanosoma vivax in domestic animals from selected districts of Tigray and Afar regions, Northern Ethiopia

Background

African animal trypanosomosis, transmitted cyclically by tsetse flies or mechanically by other biting flies, causes serious inflictions to livestock health. This study investigates the extent of non-tsetse transmitted animal trypanosomosis (NTTAT) by Trypanosoma (T.) evansi and T. vivax in domestic animals in the tsetse-free regions of Northern Ethiopia, Afar and Tigray.

Methods

A cross sectional study was conducted on 754 dromedary camels, 493 cattle, 264 goats, 181 sheep, 84 donkeys, 25 horses and 10 mules. The microhaematocrit centrifugation technique was used as parasitological test. Plasma was collected for serodiagnosis with CATT/T.evansi and RoTat 1.2 immune trypanolysis (ITL) while buffy coat specimens were collected for molecular diagnosis with T. evansi type A specific RoTat 1.2 PCR, T. evansi type B specific EVAB PCR and T. vivax specific TvPRAC PCR.

Results

The parasitological prevalence was 4.7% in Tigray and 2.7% in Afar and significantly higher (z = 2.53, p = 0.011) in cattle (7.3%) than in the other hosts. Seroprevalence in CATT/T.evansi was 24.6% in Tigray and 13.9% in Afar and was significantly higher (z = 9.39, p < 0.001) in cattle (37.3%) than in the other hosts. On the other hand, seroprevalence assessed by ITL was only 1.9% suggesting cross reaction of CATT/T.evansi with T. vivax or other trypanosome infections. Molecular prevalence of T. evansi type A was 8.0% in Tigray and in Afar and varied from 28.0% in horses to 2.2% in sheep. It was also significantly higher (p < 0.001) in camel (11.7%) than in cattle (6.1%), donkey (6%), goat (3.8%), and sheep (2.2%). Four camels were positive for T. evansi type B. Molecular prevalence of T. vivax was 3.0% and was similar in Tigray and Afar. It didn’t differ significantly among the host species except that it was not detected in horses and mules.

Conclusions

NTTAT caused by T. vivax and T. evansi, is an important threat to animal health in Tigray and Afar. For the first time, we confirm the presence of T. evansi type B in Ethiopian camels. Unexplained results obtained with the current diagnostic tests in bovines warrant particular efforts to isolate and characterise trypanosome strains that circulate in Northern Ethiopia.

Ultrastructural investigation of antennae in three cutaneous myiasis flies: Melophagus ovinus, Hippobosca equina, and Hippobosca longipennis (Diptera: Hippoboscidae)

Melophagus ovinus (Linnaeus 1758), Hippobosca equina Linnaeus, 1758, and Hippobosca longipennis Fabricius, 1805 (Diptera: Hippoboscidae) are economically and medically important ectoparasites that can act as mechanic vectors of pathogens and cause myiasis in both human and domestic animals. As essential olfactory organs, antennae of these adult hippoboscids were examined using stereoscopic and scanning electron microscopes. General morphology of the antenna is provided in detail, combined with distribution, types, size, and ultrastructures of antennal sensilla. On the antennal funiculus, two types of sensilla are observed, including basiconic sensilla and coeloconic sensilla. Four common characters are shared among the three species: (1) the scape is either obsolete or fused with the fronto-clypeus; (2) branched antennal structures (branched pedicellar microtrichiae and branched arista with only one segment) are detected; (3) the enlarged antennal pedicel completely envelops the antennal funiculus; and (4) less types of sensilla on funiculus. Disparity and diversity of the antennal and sensory structures are analyzed from the phylogenetic and functional perspective. We suggest that hippoboscids are potential model for the study of the function of coeloconic sensilla in Calyptratae.

Molecular characterization of Trypanosoma (Megatrypanum) spp. infecting cattle (Bos taurus), white-tailed deer (Odocoileus virginianus), and elk (Cervus elaphus canadensis) in the United States

In the United States, the generally non-pathogenic trypanosome of cattle is designated Trypanosoma (Megatrypanum) theileri and is distinguished morphologically from Trypanosoma (M.) cervi, a trypanosome originally described in mule deer and elk. Phylogenetic studies of the Megatrypanum trypanosomes using various molecular markers reveal two lineages, designated TthI and TthII, with several genotypes within each. However, to date there is very limited genetic data for T. theileri, and none for the Megatrypanum trypanosomes found in wild ungulates, in the U.S. In this study U.S. isolates from cattle (Bos taurus), white-tailed deer (Odocoileus virginianus) (WTD), and elk (Cervus elaphus canadensis) were compared by ribosomal DNA (rDNA) sequence analysis and their incidence in cattle and WTD in south Texas counties was investigated. Phylogenetic analyses showed clear separation of the bovine and cervine trypanosomes. Both lineages I and II were represented in the U.S. cattle and WTD parasites. Lineage I cattle isolates were of a previously described genotype, whereas WTD and elk isolates were of two new genotypes distinct from the cattle trypanosomes. The cattle isolate of lineage II was of a previously reported genotype and was divergent from the WTD isolate, which was of a new genotype. In La Salle, Starr, Webb, and Zapata counties in south Texas a total of 51.8% of white-tailed deer were positive for trypanosomes by 18S rDNA PCR. Of the cattle screened in Webb County, 35.4% were positive. Drought conditions prevailing in south Texas when the animals were screened suggest the possibility of a vector for Trypanosoma other than the ked (Lipoptena mazamae) and tabanid flies (Tabanus spp. and Haematopota spp.).

Trypanosoma (Megatrypanum) melophagium in the sheep ked Melophagus ovinus from organic farms in Croatia: phylogenetic inferences support restriction to sheep and sheep keds and close relationship with trypanosomes from other ruminant species

Trypanosoma (Megatrypanum) melophagium is a parasite of sheep transmitted by sheep keds, the sheep-restricted ectoparasite Melophagus ovinus (Diptera: Hippoboscidae). Sheep keds were 100% prevalent in sheep from five organic farms in Croatia, Southeastern Europe, whereas trypanosomes morphologically compatible with T. melophagium were 86% prevalent in the guts of the sheep keds. Multilocus phylogenetic analyses using sequences of small subunit rRNA, glycosomal glyceraldehyde-3-phosphate dehydrogenase, spliced leader, and internal transcribed spacer 1 of the rDNA distinguished T. melophagium from all allied trypanosomes from other ruminant species and placed the trypanosome in the subgenus Megatrypanum. Trypanosomes from sheep keds from Croatia and Scotland, the only available isolates for comparison, shared identical sequences. All biologic and phylogenetic inferences support the restriction of T. melophagium to sheep and, especially, to the sheep keds. The comparison of trypanosomes from sheep, cattle, and deer from the same country, which was never achieved before this work, strongly supported the host-restricted specificity of trypanosomes of the subgenus Megatrypanum. Our findings indicate that with the expansion of organic farms, both sheep keds and T. melophagium may re-emerge as parasitic infections of sheep.

Multilocus phylogeographical analysis of Trypanosoma (Megatrypanum) genotypes from sympatric cattle and water buffalo populations supports evolutionary host constraint and close phylogenetic relationships with genotypes found in other ruminants

Species of the subgenus Trypanosoma (Megatrypanum) have been reported in cattle and other domestic and wild ruminants worldwide. A previous study in Brazil found at least four genotypes infecting cattle (Bos taurus), but only one in water buffalo (Bubalus bubalis). However, the small number of isolates examined from buffalo, all inhabiting nearby areas, has precluded evaluation of their diversity, host associations and geographical structure. To address these questions, we evaluated the genetic diversity and phylogeographical patterns of 25 isolates from water buffalo and 28 from cattle from four separate locations in Brazil and Venezuela. Multigene phylogenetic analyses of ssrRNA, internal transcribed spacer of rDNA (ITSrDNA), 5SrRNA, glycosomal glyceraldehyde 3-phosphate dehydrogenase (gGAPDH), mitochondrial cytochrome b (Cyt b), spliced leader (SL) and cathepsin L-like (CATL) sequences positioned all isolates from sympatric and allopatric buffalo populations into the highly homogeneous genotype TthIA, while the cattle isolates were assigned to three different genotypes, all distinct from TthIA. Polymorphisms in all of these sequences separated the trypanosomes infecting water buffalo, cattle, sheep, antelope and deer, and suggested that they correspond to separate species. Congruent phylogenies inferred with all genes indicated a predominant clonal structure of the genotypes. The multilocus analysis revealed one monophyletic assemblage formed exclusively by trypanosomes of ruminants, which corresponds to the subgenus T. (Megatrypanum). The high degree of host specificity, evidenced by genotypes exclusive to each ruminant species and lack of genotype shared by different host species, suggested that the evolutionary history of trypanosomes of this subgenus was strongly constrained by their ruminant hosts. However, incongruence between ruminant and trypanosome phylogenies did not support host-parasite co-evolution, indicating that host switches have occurred across ruminants followed by divergences, giving rise to new trypanosome genotypes adapted exclusively to one host species.

High genetic diversity in field isolates of Trypanosoma theileri assessed by analysis of cathepsin L-like sequences disclosed multiple and new genotypes infecting cattle in Thailand

In this study, we describe the first survey in Thailand of Trypanosoma theileri, a widespread and prevalent parasite of cattle that is transmitted by tabanid flies. Investigation of 210 bovine blood samples of Thai cattle from six farms by hematocrit centrifuge technique (HCT) revealed 14 samples with trypanosomes morphologically compatible to T. theileri. Additional animals were positive for T. theileri by PCR based on the Cathepsin L-like sequence (TthCATL-PCR) despite negative by HCT, indicating cryptic infections. Results revealed a prevalence of 26 ± 15% (95% CI) of T. theileri infection. Additionally, 12 samples positive for T. theileri were detected in cattle from other 11 farms. From a total of 30 blood samples positive by HCT and/or PCR from 17 farms, seven were characterized to evaluate the genetic polymorphism of T. theileri through sequence analysis of PCR-amplified CATL DNA sequences. All CATL sequences of T. theileri from Thai cattle clustered with sequences of the previously described phylogenetic lineages TthI and TthII, supporting only two major lineages of T. theileri in cattle around the world. However, 11 of the 29 CATL sequences analyzed showed to be different, disclosing an unexpectedly large polymorphic genetic repertoire, with multiple genotypes of T. theileri not previously described in other countries circulating in Thai cattle.