Detecting and differentiating Theileria sergenti and Theileria sinensis in cattle and yaks by PCR based on major piroplasm surface protein (MPSP)

Putative target sites in synganglion for novel ixodid tick control strategies

Acaricide resistance is a global problem that has impacts worldwide. Tick populations with broad resistance to all commercially available acaricides have been reported. Since resistance selection in ticks and their role in pathogen transmission to animals and humans result in important economic and public health burden, it is essential to develop new strategies for their control (i.e., novel chemical compounds, vaccines, biological control). The synganglion is the tick central nervous system and it is responsible for synthesizing and releasing signaling molecules with different physiological functions. Synganglion proteins are the targets of the majority of available acaricides. In this review we provide an overview of the mode-of-action and resistance mechanisms against neurotoxic acaricides in ticks, as well as putative target sites in synganglion, as a supporting tool to identify new target proteins and to develop new strategies for tick control.

Multiplex PCR for rapid differential diagnosis of co-prevalent species of Theileria (Theileria annulata and Theileria orientalis) in cattle

Theileriosis is a tick-borne disease that causes enormous losses in the dairy industry. There are several species of Theileria that can infect bovines. Generally, more than one species are prevalent in any geographical area; thus, chances of co-infections are high. Differentiation of these species may not be possible by microscopic examination or serological tests. Therefore, in this study, a multiplex PCR assay was standardized and evaluated for rapid and simultaneous differential detection of two species of Theileria viz., Theileria annulata and Theileria orientalis. Species-specific primers were designed to target the merozoite piroplasm surface antigen gene (TAMS1) of T. annulata and the major piroplasm surface protein gene of T. orientalis, yielding specific amplicon of 229 bp and 466 bp, respectively. The sensitivity of multiplex PCR was 10² and 10³ copies for T. annulata and T. orientalis, respectively. The simplex and multiplex PCRs were specific and showed no cross-reactivity with other hemoprotozoa for either primer. For comparative evaluation, blood samples from 216 cattle were tested by simplex and multiplex PCR for both species. Using multiplex PCR, 131 animals were found infected for theileriosis, of which 112 were infected with T. annulata, five were infected with T. orientalis, and 14 had mixed infections. This is the first report of T. orientalis from Haryana, India. Representative sequences of T. annulata (ON248941) and T. orientalis (ON248942) were submitted in GenBank. The standardized multiplex PCR assay used in this study was specific, sensitive, for the screening of field samples.

Survey of tick species and molecular detection of selected tick-borne pathogens in Yanbian, China

Ticks and tick-borne diseases pose a significant threat to public health. In this study, we aimed to determine the tick species distribution and pathogens carried by ticks in Yanbian, China. A total of 2673 questing ticks were collected from eight counties and cities in Yanbian and were morphologically identified. The presence of Candidatus Rickettsia tarasevichiae (CRT), spotted fever group Rickettsia (SFGR), severe fever thrombocytopenia syndrome virus (SFTSV), Theileria, and other pathogens was confirmed using polymerase chain reaction (PCR) and real-time quantitative PCR assays, followed by phylogenetic and genotypic analyses. According to the morphological identification, the tick species in Yanbian consisted of Haemaphysalis longicornis, Ixodes persulcatus, Dermacentor silvarum, H. japonica, and H. concinna. In H. longicornis, CRT, SFGR, SFTSV and Theileria orientalis were detected, while CRT, SFGR, and SFTSV were detected in I. persulcatus, H. japonica, and D. silvarum. Only SFTSV was detected in H. concinna. Mixed infection with CRT and SFTSV was observed in I. persulcatus and H. japonica. The gene sequences of all tested pathogens exhibited 95.7%–100% identity with the corresponding sequences deposited in GenBank. Phylogenetic analysis showed that different SFGR and SFTSV genotypes were closely related to the Korean strains. This study is the first to describe the genetic diversity of SFGR Candidatus Rickettsia longicornii in H. longicornis in Yanbian, China, using the ompA, ompB, sca4, and rrs genes. These results provide epidemiological data to support the prevention and control of ticks and tick-borne diseases in the border areas of China, North Korea, and Russia.

Molecular epidemiology and genetic characterization of Theileria orientalis in cattle

Theileria orientalis (T. orientalis) is a benign species of Theileria that is found all throughout the world, including Egypt. The purpose of this work was to determine the current status of T. orientalis infection in cattle, as well as to define T. orientalis genetic diversity using the major piroplasm surface protein (MPSP) genes. In 2020, blood samples from 500 asymptomatic cattle were collected, which live in four different governorates at northern Egypt and examined using PCR assay based on MPSP gene. Overall, 44 blood samples (8.8%, 44/500) were positive for T. orientalis, and the highest prevalence rate was observed in Kafer ElSheikh while it was relatively low in Gharbia governorate. Moreover, based on multivariable analysis, the risk of infection with T. orientalis infection was higher in mixed breed cattle and in animals of age group more than 3 years compared to other. Additionally, absence of acaricide application, infestation with ticks, and communal grazing system were identified as potential risk factors for T. orientalis infection. Phylogenetic analysis revealed that the isolates studied belonged to two MPSP genotypes, types 1 and 2. These findings reveal that the MPSP genotypes discovered in the present work displayed genetic variation that was linked to geographic area. Therefore, further research should be focused on developing an effective T. orientalis monitoring and preventive program.

Establishment and application of a qPCR diagnostic method for Theileria annulata

Bovine theileriosis caused by several Theileria species including Theileria annulata, Theileria parva, Theileria orientalis, Theileria mutans, and Theileria sinensis is a significant hemoprotozoan tick-borne disease. Among these, Theileria species, T. annulata, which causes tropical theileriosis (TT), is regarded as one of the most pathogenic and is responsible for high mortality. At present, most conventional diagnostic methods for tropical theileriosis are time-consuming and laborious and cannot distinguish newfound T. sinensis in China. Therefore, a high sensitivity and specificity real-time quantitative PCR method based on the TA19140 target molecule was developed, and the method was found to be specific for T. annulata. No cross-reaction was observed with T. sinensis, T. orientalis, Babesia bovis, Babesia bigemina, or Hyalomma anatolicum which is negative for T. annulata. A total of 809 field samples from different regions of China were analyzed by using the developed qPCR and conventional PCR. The positive samples for T. annulata detected by real-time qPCR and conventional PCR were 66/809 (8.16%) and 20/809 (2.47%), respectively, and all positive amplicons by qPCR were confirmed by Sanger sequencing. The results showed that the developed qPCR for the T. annulata 19,140 gene was more sensitive than conventional PCR. In addition, we first discovered that TA19140 was mainly expressed at the schizont and merozoite stages of T. annulata by relative quantification. The protein encoded by the TA19140 gene may be used as a potential diagnostic antigen for tropical theileriosis. In conclusion, a real-time quantitative PCR diagnostic method targeting the TA19140 gene was successfully established and could be used for both the quantitative and qualitative analysis of T. annulata infection from cattle and vector ticks, which will greatly help to control and diagnosis of tropical theileriosis.

Prevalence of Theileria in cattle in China: A systematic review and meta-analysis

Theileria, one of the causative agents of blood protozoan, has brought a huge economic loss to the cattle industry worldwide. However, the epidemiology of Theileria in Chinese cattle has not been systematically investigated. This comprehensive review aimed at investigating the prevalence of Theileria infection in cattle in China. A total of 48 published papers on Theileria infection in cattle in China (including data from 21,366 animals) from inception to October 8, 2021 met the inclusion standard after searching in five databases (Technology Periodical Database, Wan Fang Database, China National Knowledge Infrastructure, PubMed, and ScienceDirect). The pooled prevalence of Theileria in cattle in China was 32.4% identified by using a random effects model. The prevalence in Northeastern China (45.3%) was higher than that in other regions. In the sex subgroup, the prevalence of Theileria was higher in females (48.9%) than that in males (45.8%). The prevalence of Theileria was higher in cattle of free range (34.4%) compared with that of intensive farming (22.3%). The prevalence prior to 2013 (36.1%) was higher than that after 2013 (33.6%). Among three cattle species, dairy cows had the lowest prevalence (21.5%). The prevalence of Theileria (T.) annulata (22.2%) and T. sergenti (26.2%) was higher than other species of Theileria (T. buffeli: 17.5%, T. luwenshuni: 0.9%, T. orientalis: 15.5%, T. ovis: 0.21%, T. sinensis: 20.2%, T. uilenbergi: 6.2%, Others: 0.9%). We also analyzed the impact of different geographic factor subgroups (longitude, latitude, precipitation, temperature, humidity, and altitude) on the prevalence of Theileria in cattle. Among them, climatic factors of longitude, latitude, precipitation, humidity, temperature were associated with the prevalence of Theileria. These analyses suggested that Theileria was common in cattle in China. Targeted prevention programs based on geographic and climatic conditions in different areas may play an important role in reducing Theileria infection among cattle.

The Common Occurrence of Theileria ovis in Tibetan Sheep and the First Report of Theileria sinensis in Yaks from Southern Qinghai, China

PURPOSE

The tick-borne protozoa piroplasms, including Theileria and Babesia, are the cause of substantial economic losses to the livestock industry. However, in southern Qinghai province, China, there are limited information on the molecular characteristics of piroplasms. This study therefore aimed at determining the prevalence and genetic diversity of piroplasms.

METHODS

In order to detect piroplasms, we examined 330 yaks and 236 Tibetan sheep blood samples by nested PCR. The differences in piroplasms prevalence in relation to different risk factors was analyzed using SPSS 26. Phylogenetic analysis based on 18S rRNA sequences was inferred using MEGA 7.

RESULTS

During this study, Theileria spp. were detected in 33.6% (111/330) of yaks and 94.1% (222/236) of Tibetan sheep, but no Babesia was identified. Importantly, a comparison study revealed that T. ovis infection was highly prevalent in sheep (94.1%) but infrequent in yaks (6.1%), while T. sinensis was host-specific to yaks with an infection rate of 27.6%. In addition, male animals were more likely to be infected by T. sinensis and female animals were more likely to be infected by T. ovis. And animals below 4000 m areas reported a higher infection rate with T. sinensis (26.1% vs. 2.9%, p < 0.001). Alongside these differences in prevalence, we found a significantly higher T. sinensis infection rate in separated-grazing livestock (22.2% vs. 3.7%, p < 0.001), while mixed-grazing ruminants had a higher T. ovis infection rate (50.0% vs. 39.0%, p = 0.014). Furthermore, sequence analysis revealed that the 18S rRNA sequences obtained in this study shared 86.9-100.0% identities with each other and they were clustered into T. sinensis or T. ovis.

CONCLUSION

To our knowledge, this is the first report of T. sinensis in Qinghai region. In addition, high prevalence of the generally sub-clinical T. ovis in sheep indicates extensive exposure to ticks and transmission of tick-borne pathogens with a significant economic impact. This study provides insights into the distribution and genetic diversity of Theileria in China.

Morphological, molecular and MALDI-TOF MS identification of ticks and tick-associated pathogens in Vietnam

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has been reported as a promising and reliable tool for arthropod identification, including the identification of alcohol-preserved ticks based on extracted leg protein spectra. In this study, the legs of 361 ticks collected in Vietnam, including 251 Rhiphicephalus sanguineus s.l, 99 Rhipicephalus (Boophilus) microplus, two Amblyomma varanensis, seven Dermacentor auratus, one Dermacentor compactus and one Amblyomma sp. were submitted for MALDI-TOF MS analyses. Spectral analysis showed intra-species reproducibility and inter-species specificity and the spectra of 329 (91%) specimens were of excellent quality. The blind test of 310 spectra remaining after updating the database with 19 spectra revealed that all were correctly identified with log score values (LSV) ranging from 1.7 to 2.396 with a mean of 1.982 ± 0.142 and a median of 1.971. The DNA of several microorganisms including Anaplasma platys, Anaplasma phagocytophilum, Anaplasma marginale, Ehrlichia rustica, Babesia vogeli, Theileria sinensis, and Theileria orientalis were detected in 25 ticks. Co-infection by A. phagocytophilum and T. sinensis was found in one Rh. (B) microplus.

Molecular detection of Theileria species, Anaplasma species, Candidatus Mycoplasma haemobos, Trypanosoma evansi and first evidence of Theileria sinensis-associated bovine anaemia in crossbred Kedah-Kelantan x Brahman cattle

BACKGROUND

Serious disease outbreaks in cattle are usually associated with blood pathogens. This study aims to detect blood pathogens namely Theileria species, Anaplasma species, Candidatus Mycoplasma haemobos and Trypanosoma evansi, and determine their phylogenetic relationships and haemato-biochemical abnormalities in naturally infected cattle.

METHODS

Molecular analysis was achieved by PCR amplification and sequencing of PCR amplicons of 18SrRNA gene of Theileria species, 16SrRNA genes of Anaplasma and Mycoplasma species, MPSP genes of T. orientalis and T. sinensis, MSP4 gene of A. marginale, 16SrRNA gene of Candidatus Mycoplasma haemobos, and RoTat1.2 VSG gene of Trypanosoma evansi, in sixty-one (61) clinically ill Kedah-Kelantan x Brahman cattle in Pahang, Malaysia.

RESULTS

A total of 44 (72.13%) cattle were infected with more than one blood pathogen. Theileria species was the blood pathogen with the highest molecular detection rate (72.13, 95% CI 59.83-81.81%). Nucleotide blast analyses of all sequences demonstrated high degree of molecular similarity (98-100%) in comparison with their respective reference sequences. Analysis of 18SrRNA gene sequences of Theileria species and 16SrRNA gene sequences of Anaplasma species revealed Theileria sinensis and Anaplasma platys respectively as additional species detected in these cattle. MPSP-PCR analysis was conducted for further confirmation of T. sinensis. The blood picture of eight infected cattle groups revealed poikilocytosis, anisocytosis, rouleaux formation and degenerative left shift. High mean erythrocyte fragility values were common in infected cattle groups. Anaemia of the macrocytic normochromic type and spherocytes were observed in the T. evansi and Anaplasma platys + Theileria sinensis double species co-infected cattle group. Normocytic normochromic anaemia was observed in the T. sinensis infected cattle group. Significant (p < 0.05) increases in serum liver and kidney parameters, total protein, globulin, total and unconjugated bilirubin and decreased albumin values were observed in the T. evansi infected cattle when compared to clinically healthy cattle.

CONCLUSION

We present the first evidence of Theileria sinensis-associated bovine anaemia (TSABA) in Malaysian cattle. Because of the high occurrence of bovine theileriosis and detection of A. platys, there is an urgent need for appropriate preventive and control measures against these blood pathogens.

Laurent B, Fritz ML, Serre D. High-throughput detection of eukaryotic parasites and arboviruses in mosquitoes

Vector-borne pathogens cause many human infectious diseases and are responsible for high mortality and morbidity throughout the world. They can also cause livestock epidemics with dramatic social and economic consequences. Due to its high costs, vector-borne disease surveillance is often limited to current threats, and the investigation of emerging pathogens typically occurs after the reports of clinical cases. Here, we use high-throughput sequencing to detect and identify a wide range of parasites and viruses carried by mosquitoes from Cambodia, Guinea, Mali and the USA. We apply this approach to individual Anopheles mosquitoes as well as pools of mosquitoes captured in traps; and compare the outcomes of this assay when applied to DNA or RNA. We identified known human and animal pathogens and mosquito parasites belonging to a wide range of taxa, as well as DNA sequences from previously uncharacterized organisms. Our results also revealed that analysis of the content of an entire trap could be an efficient approach to monitor and identify rare vector-borne pathogens in large surveillance studies. Overall, we describe a high-throughput and easy-to-customize assay to screen for a wide range of pathogens and efficiently complement current vector-borne disease surveillance approaches.

Genetic Diversity of Bovine Hemoprotozoa in South Korea

Tick-borne pathogens cause economically significant diseases in cattle. Theileria spp. are parasitic protozoa and the causative agent of bovine theileriosis. Here we report the distribution and risk factors of bovine Theileria using blood samples taken between 2018 and 2019. Of 737 tested cattle, nine animals (1.2%) were positive for Theileria orientalis infection by 18S rRNA gene amplification. Further analysis of the infected samples using the T. orientalis major piroplasm surface protein (MPSP) gene revealed five different genotypes circulating in the population: Types 1, 2, 3, 7, and N3. To the best of our knowledge, this is the first research to describe the existence of the T. orientalis MPSP genotype N3 in South Korea. Although the prevalence of bovine T. orientalis was low, our study offers data on the geographical distribution and prevalence of bovine Theileria spp. in South Korea. Further studies are warranted to determine the correlation of clinical symptoms with parasite MPSP genotypes. Our data provide epidemiological information to help control bovine theileriosis in South Korea.

Clinical Pathology, Immunopathology and Advanced Vaccine Technology in Bovine Theileriosis: A Review

Theileriosis is a blood piroplasmic disease that adversely affects the livestock industry, especially in tropical and sub-tropical countries. It is caused by haemoprotozoan of the Theileria genus, transmitted by hard ticks and which possesses a complex life cycle. The clinical course of the disease ranges from benign to lethal, but subclinical infections can occur depending on the infecting Theileria species. The main clinical and clinicopathological manifestations of acute disease include fever, lymphadenopathy, anorexia and severe loss of condition, conjunctivitis, and pale mucous membranes that are associated with Theileria-induced immune-mediated haemolytic anaemia and/or non-regenerative anaemia. Additionally, jaundice, increases in hepatic enzymes, and variable leukocyte count changes are seen. Theileria annulata and Theileria parva induce an incomplete transformation of lymphoid and myeloid cell lineages, and these cells possess certain phenotypes of cancer cells. Pathogenic genotypes of Theileria orientalis have been recently associated with severe production losses in Southeast Asia and some parts of Europe. The infection and treatment method (ITM) is currently used in the control and prevention of T. parva infection, and recombinant vaccines are still under evaluation. The use of gene gun immunization against T. parva infection has been recently evaluated. This review, therefore, provides an overview of the clinicopathological and immunopathological profiles of Theileria-infected cattle and focus on DNA vaccines consisting of plasmid DNA with genes of interest, molecular adjuvants, and chitosan as the most promising next-generation vaccine against bovine theileriosis.

Molecular Survey and Genetic Diversity of Babesia spp. and Theileria spp. in Cattle in Gansu Province, China

PURPOSE

Babesia spp. and Theileria spp. are tick-borne pathogens of livestock globally. In this study, we investigated the presence and distribution of these pathogens in cattle from 20 locations in 4 Counties of Wuwei City. The aim of the present research was to evaluate the spread of piroplasms, so as to provide the epidemiological information for control piroplasmosis in the region.

METHODS

The authors provided the molecular data for Babesia spp. and Theileria spp. and analyzed the obtained sequences of the 18S rRNA gene, Tams1 gene and MPSP gene by using the ClustalW program in MEGA version 6.06 software and BLASTn tool of NCBI GenBank database.

RESULTS

The total infection rates were detected by nPCR with 1.8% for T. orientalis, 3% for T. sinensis, 0.6% for T. annulata, 1.8% for B. motasi and 0.6% for B. bigemina.

CONCLUSIONS

To the best of our knowledge, this is the first report investigating T. sinensis from cattle by PCR in Wuwei City. In particular, ovine B. motasi has been for the first time detected in cattle in our study and its impact is worth discussing to figure out the potential reasons.

Molecular characterization of tick-borne bacteria and protozoans in yaks (Bos grunniens), Tibetan sheep (Ovis aries) and Bactrian camels (Camelus bactrianus) in the Qinghai-Tibetan Plateau Area, China

Due to the specific plateau climate, a variety of unique animals live in the Qinghai-Tibetan Plateau Area (QTPA) including yaks (Bos grunniens), Tibetan sheep (Ovis aries) and Bactrian camels (Camelus bactrianus). However, information on tick-borne diseases (TBDs) in the QTPA and on the molecular characteristics of tick-borne pathogens (TBPs) in the area is limited. Therefore, the aim of this study was to investigate Anaplasma spp., Babesia spp., Theileria spp., Borrelia burgdorferi sensu lato and Rickettsia spp. infecting yaks, Tibetan sheep and camels in this area. A total of 276 animals were screened. Overall, 84.5% (164/194) of yaks, 58% (23/40) of Tibetan sheep, and 38% (16/42) of camels tested positive for at least one pathogen. Theileria spp., Anaplasma ovis and spotted fever group (SFG) Rickettsia spp. were detected as TBPs in the current study with overall infection rates of 10.9% (30/276), 8.3% (23/276) and 62.9% (171/276), respectively. Further study revealed that 1.5% (3/194) of the yaks were infected with Theileria sp. OT3, 1.5% (3/194) with T. luwenshuni, 6.2% (12/194) with T. uilenbergi, 1.1% (2/194) with T. ovis and 82% (159/194) with SFG Rickettsia spp. It was also shown that 58% (23/40) of the Tibetan sheep were infected with A. ovis and 15% (6/40) with T. ovis. Among the camels, 10% (4/42) were infected with T. equi, while 29% (12/42) were positive for Rickettsia spp. Sequence analysis revealed that the Rickettsia spp. infecting yaks and camels were Rickettsia raoultii and Rickettsia slovaca. To the best of our knowledge, this study reports the first detection and characterization of these pathogens in yaks, Tibetan sheep and camels in the country, except for T. luwenshuni infections in yaks.

Genotypic Analysis of Piroplasms and Associated Pathogens from Ticks Infesting Cattle in Korea

Tick-borne pathogens (TBPs) impose an important limitation to livestock production worldwide, especially in subtropical and tropical areas. Earlier studies in Korea have examined TBPs residing in ticks and animals; however, information on multiple TBPs in ticks infesting cattle is lacking. This study assessed the prevalence of TBPs in ticks parasitizing cattle. A total of 576 ticks, including 340 adults and 236 nymphs, were collected from cattle in Korea between 2014 and 2018. All ticks collected were identified as Haemaphysalis longicornis based on their morphological and molecular characteristics. Among piroplasms and other tick-associated pathogens, seven TBP genes, namely Theileria orientalis (5.0%), Anaplasma bovis (2.3%), Anaplasma capra (4.7%), Anaplasma phagocytophilum-like Anaplasma spp. (APL) clades A (1.9%) and B (0.5%), Ehrlichia canis (1.6%), and Candidatus Rickettsia longicornii (17.5%), were detected. Bartonella spp. and severe fever with thrombocytopenia syndrome virus were not found. To our knowledge, this is the first study to report the presence of the pathogens T. orientalis major piroplasm surface protein genotypes 3 and 7, A. capra, and APL in ticks from Korea. Cattle ticks may be maintenance hosts for many TBPs, and veterinary and medical clinicians should be aware of their high probability of infection and clinical complexity in humans.

Molecular prevalence of Theileria infections in cattle in Yanbian, north-eastern China

Bovine Theileria are tick-borne protozoan parasites that invade bovine erythrocytes and lymphocytes. Three main bovine Theileria species have been identified in China: T. orientalis, T. sinensis, and T. annulata. To examine the prevalence of bovine theileriosis in Yanbian, a total of 584 bovine blood samples were collected from five localities from 2017 to 2019 and analyzed by PCR. Six pairs of oligonucleotide primers directed against the 18S rRNA gene of Theileria spp., Tams-1 gene of T. annulata, MPSP gene of T. orientalis, and T. sinensis, were used to detect these parasites. A sequence analysis of the amplified genes confirmed that the Theileria species were T. orientalis and T. sinensis, without T. annulata. The overall prevalence of Theileria in cattle was 42.81% (250/584). Out of the 584 samples, 159 (27.23%) and 157 (26.88%) were positive for T. sinensis and T. orientalis, respectively, and the mixed infection rate was 11.30% (66/584). The total prevalence of bovine Theileria species in Helong, Hunchun, Longjing, Yanji, and Dunhua was 66.28%, 49.68%, 23.81%, 28.15%, and 0%, respectively. These results provide epidemiological data for the prevention and control of bovine Theileria species in Yanbian, China.

First Report of Theileria Infection of Bactrian Camels (Camelus bactrianus) in Xinjiang, China

INTRODUCTION

Protozoan Theileria is transmitted by tick vectors to some animals worldwide and causes considerable economic damage. The detection of pathogens in camels is not only crucial for the preservation of species but also provides important information on the epidemiologic chain of diseases.

MATERIALS AND METHODS

We conducted a molecular detection in Xinjiang, China to assess the impact of Theileria infection in Bactrian camels and ticks in 2016. The 18S rRNA and MPSP gene sequences of T. sinensis obtained from Bactrian camels and ticks in Xinjiang, China have been deposited in the GenBank database.

RESULTS

PCR revealed that 6.56% of the Bactrian camel blood samples, 2.75% of Rhipicephalus sp., 3.81% of Hy. asiaticum, 4.32% of Hy. dromedarii, and 0% of D. niveus tick samples were positive for T. sinensis, respectively; no other Theileria and Babesia were found in these samples and D. niveus samples. The results showed that one Theileria parasite, Theileria sinensis, was found in Bactrian camels (Camelus bactrianus), Rhipicephalus sp., Hy. asiaticum, and Hy. dromedarii in Xinjiang, respectively.

CONCLUSION

This is the first detection of T. sinensis DNA in Bactrian camels from China. Our results provide important data to increase the understanding of theileriosis of Bactrian camel, and will aid in taking effective measures to control theileriosis transmission to camels, cattle and other ruminants in Xinjiang, China.

Molecular epidemiology and risk factors of Anaplasma spp., Babesia spp. and Theileria spp. infection in cattle in Chongqing, China

Tick-borne pathogens (TBPs) seriously affect cattle production and can be economically damaging. The epidemiology of these organisms in the Chongqing municipality of China is not well described. This study aimed to investigate the prevalence and risk factors of TBPs including Anaplasma spp., Babesia spp. and Theileria spp. in cattle in Chongqing municipality. The results showed that 43.48% (150/345) of cattle were infected with at least one TBP, of which single infections were detected in 104 (30.14%), double infections in 34 cattle (9.86%) and triple infections in 12 (3.48%) of the cattle. The overall prevalence of Anaplasma spp., Theileria spp. and B. bigemina were 22.32%, 23.19% and 7.24%, respectively. Among these, the prevalence of A. bovis, A. central, A. phagocytophilum, A. platys, A. marginale, T. sinensisi and T. orientalis were 8.41%, 7.83%, 4.93%, 4.35%, 2.61%, 22.32% and 2.60%, respectively. We could not detect B. bovis, T. annulata, T. luwenshuni or T. uilenbergi in cattle. Cattle ≥1-year-old were more likely to be infected with Theileria spp. [adjusted odd ratio (AOR) = 2.70, 95% CI = 1.12-6.56)] compared with younger cattle, while cattle ≥1-year-old had reduced susceptibility to B. bigemina (AOR = 0.14, 95% CI = 0.03-0.60). Cattle living at higher altitude (≥500 m) were more susceptible to B. bigemina (AOR = 6.97, 95% CI = 2.08-23.35) and Theileria spp. infection (AOR = 1.87, 95% CI = 1.06-3.32). The prevalence of Theileria spp. on farms with cats was significantly higher than that without cats (AOR = 2.56, 95% CI = 1.12-5.88). Infection with A. bovis and A. central were significantly associated with A. phagocytophilum infection. Furthermore, there were significant associations between A. bovis and A. central infection, T. sinensisi and A. marginale infection, and B. bigemina and T. orientalis infection. This study provides new data on the prevalence of Anaplasma spp., Babesia spp. and Theileria spp. in cattle in Chongqing, and for the first time we reveal a possible relationship between the afore-mentioned pathogens, which will help in formulating appropriate control strategies for these pathogens in this area.

Genetic characterization of Theileria species infecting bovines in India

Genetic characterization of Theileria species infecting bovines in India was attempted targeting the 18S ribosomal RNA region of the parasite. Blood samples of bovines (n = 452), suspected for haemoprotozoan infections, from 9 different states of the country were microscopically examined for Theileria species infection. Four Theileria spp. positive blood samples from each state were randomly utilized for PCR amplification of the 18S rRNA gene (approx. 1529 bp) followed by cloning and sequencing. The sequence data analysis of all the 36 isolates revealed that 33 isolates had high sequence similarity with published sequences of T. annulata, whereas 3 isolates (MF287917, MF287924 and MF287928) showed close similarity with published sequences of T. orientalis. Sequence homology within the isolates ranged between 95.8 and 100% and variation in the length of targeted region was also noticed in different isolates (1527-1538 nt). Phylogenetic tree created for T. annulata sequences revealed that a total of 24 Indian isolates formed a major clade and grouped together with isolates originating from countries like China, Spain, Turkey and USA. Remaining 09 isolates clustered in a separate group and were closely related to the TA5 isolate of T. annulata (a new genotype) originating from India and also with the isolates from East Asian countries like Japan and Malaysia. All the three T. orientalis isolates had minimal intraspecific variation (99-100% homology) amongst themselves. Further, in the phylogenetic analysis T. orientalis Indian isolates were found to cluster away from other 14 isolates of T. buffeli/sergenti/orientalis originating from different countries (Australia, China, Indonesia and Spain). However, these 3 isolates clustered together with the T. buffeli Indian isolate (EF126184). Present study confirmed the circulation of different genotypes of T. annulata in India, along with T. orientalis isolates.

Socio-economic burden of parasitic infections in yaks from 1984 to 2017 on Qinghai Tibetan Plateau of China-A review

Yak is an important animal for the Tibetans at Qinghai-Tibetan Plateau of China. The burden of parasitic diseases has been a major threat to the health of yaks at this region presenting a considerable socio-economic losses and impact to yak production and local nomads. Keeping in view, we collected the published papers from 1984 to 2017 on major parasitic infections in yaks by electronic literature search from five databases including CNKI, Google, PubMed, Science Direct and Web of Science. The prevalence of Eimeria, Babesia, Theileria, Hypodermosis, Cystic echinococcosis, Alveolar echinococcosis, Toxoplasma gondii, Neospora caninum, Cryptosporidium, Giardia duodenalis, Enterocytozoon bieneusi, Toxocara vitulorum, and Fascioliasis infection in yaks was found to be 48.02%, 13.06%, 36.11%, 59.85%, 16.93%, 0.99%, 20.50%, 5.14%, 10.00%, 3.68%, 4.07%, 22.23% and 28.7% respectively. Data presented are contemplated to enhance our current understanding on the major parasitic diseases of yaks at Qinghai Tibetan plateau, China. The main aim of this effort is to ameliorate the effects of the parasitic burden in this specie; so that, the attempts are made to minimize the incidence of these infections in future to raise the socio-economic levels of local community.

Common occurrence of Theileria annulata and the first report of T. ovis in dairy cattle from Southern Xinjiang, China

Bovine theileriosis is a common tick-born disease infected by Theileria spp. causing loss of beef and dairy cattle worldwide, therefore, the aim of this study was to determine the prevalence and genetic diversity of Theileria spp. in Southern Xinjiang Uyghur Autonomous Region, China. We screened 493 dairy cattle blood samples from Southern Xinjiang to detect Theileria spp. by PCR. The overall prevalence of Theileria spp. was 23.5% (116/493). The most frequent Theileria sp. was Theileria annulata 22.5% (111/493), followed by T. orientalis (0.6%, 3/493) and T. ovis (0.2%, 1/493). Additionally, one sample was co-infected with T. annulata and T. orientalis. Phylogenetic analysis showed that the 11 T. annulata Tams1 sequences grouped into three sequence clusters that belonged to group 2 (Asia group) and shared 96.4% to 99.9% identity with to each other. Furthermore, our results revealed the presence of several T. orientalis MPSP genotypes (types 1, 2, and 5) in this region. In this study, T. annulata was found to be the most prevalent Theileria species in dairy cattle from Southern Xinjiang. Theileria ovis was detected in one DNA sample of a free-grazing dairy cow from China for the first time.

Molecular investigation of piroplasma infection in white yaks (Bos grunniens) in Gansu province, China

Piroplasmosis, including theileriosis and babesiosis, is a tick-borne haemoprotozoan disease responsible for huge economic losses to livestock industry. In China, the biology of piroplasms infective to cattle was well understood on the basis of pathogen isolations and molecular epidemiological surveys in the past few decades. But very limited information about the infection status of piroplasms in white yak (Bos grunniens), a semi-wild and endemic breed, has been recorded, so far. A total of 350 blood samples was collected from white yaks in 11 towns of Tianzhu Tibetan Autonomous County of Gansu province, China, during April to July 2015. The samples were tested using species-specific polymerase chain reaction (PCR) for Babesia bovis, B. bigemina, Theileria annulata, T. orientalis and T. sinensis. Positive samples were further sequenced and confirmed via sequence alignment. The results showed a high prevalence of piroplasms in the white yaks, 38.3%(134/350). Four Babesia/Theileria species were detected. The prevalences were 8.3% (B. bigemina), 7.7% (T. annulata), 9.7% (T. orientalis) and 26.0% (T. sinensis).No B. bovis-positive samples were detected. The single infections of B. bigemina, T. annulata, T. orientalis and T. sinensis were 2.3%, 2.6%, 5.1% and 16.9%, respectively. 11.4%(40/350) of these animals presented co-infections with 2 or 3 parasite species, in which 80.0% of co-infection had T. sinensis infection and no co-infections with 4 parasite species was detected. This is the first report to investigate the Babesia/Theileria infection in white yaks using molecular diagnostic method, for detection of B. bigemina, T. annulata, T. sergenti and T. sinensis. The findings also offer novel insights into the role of white yaks in Babesia/Theileria epidemiology and valuable information for the control and management of piroplasmosis in white yaks.

Evaluating an indirect rMPSP enzyme-linked immunosorbent assay for the detection of bovine Theileria infection in China

Bovine theileriosis, a tick-borne protozoan disease caused by Theileria annulata, Theileria orientalis and Theileria sinensis, is widespread in China and is a serious economic problem for the Chinese livestock industry. In this study, recombinant major piroplasma surface proteins (MPSP) of T. annulata, T. orientalis and T. sinensis based on MPSP genes were expressed in Escherichia coli BL21(DE3). The immunogenicity and specificity of the three purified recombinant MPSP proteins were evaluated with the reference positive sera of T. annulata, T. orientalis, T. sinensis, Babesia bovis, B abesia bigemina, Babesia major, Babesia motasi, Theileria luwenshuni, Theileria uilenbergi and Anaplasma ovis using an enzyme-linked immunosorbent assay (ELISA) or western blotting. The results showed that all three of the rMPSP proteins had a strong reaction with the sera from cattle infected with T. annulata, T. orientalis and T. sinensis via western blotting but not with other piroplasma and Anaplasma species. Then, the rMPSP protein of T. sinensis was used to develop an iELISA for detecting the three Theileria species infections. The specificity and sensitivity were 95.7 and 95.5 %, respectively, with a threshold of 28.8 % of the specific mean antibody rate (AbR). Finally, 2473 field-collected bovine sera, from 42 prefectures of 17 provinces in China, were tested using the ELISA to evaluate the prevalence of bovine theileriosis, and the average positive rate was 43.6 %. The developed iELISA could be a suitable tool to detect the three bovine Theileria species, and the data also provided important information regarding the current prevalence of bovine theileriosis in China.

Genetic characterization of Theileria orientalis from cattle in the Republic of Korea

Theileria orientalis is the causative agent of benign theileriosis, which is distributed mainly in Asian countries, and causes serious economic losses in the livestock industry. The present study was performed to investigate the epidemiology of T. orientalis infections in cattle in the Republic of Korea (ROK) and to characterize the genetic diversity of T. orientalis based on the major piroplasm surface protein (MPSP) genes. In 2015, between July and August, blood samples were collected from 138 asymptomatic cattle in four different geographical regions (Hoengseong, Jeongeup, Namwon, and Jeju island) in the ROK. In total, 57 blood samples (41.3 %, 57/138) were positive for T. orientalis based on PCR amplification of the MPSP gene. A high prevalence of T. orientalis infection was observed in Jeju island, whereas the infection rate was relatively low in Jeongeup. Phylogenetic analysis showed that isolates identified in this study belonged to four MPSP genotypes, specifically types 1, 2, 3, and 7. The distribution of the four genotypes varied considerably among the four regions; types 1, 2, and 3 were detected in Jeju island, whereas types 1 and 7 were found in Namwon, types 1 and 2 in Jeongeup, and type 2 in Hoengseong. To our knowledge, this is the first report on the identification of type 7 T. orientalis in cattle in the ROK. These results suggest that the MPSP genotypes detected in this study showed genetic diversity related to geographical location. Our findings revealed that the T. orientalis infection rate was relatively high, indicating that T. orientalis infection is closely associated with grazing. Of the four MPSP genotypes, the prevalence of the most pathogenic type 2 was relatively high in the ROK. Therefore, further studies should focus on the development of an effective monitoring and prevention program for T. orientalis.

Genome-wide patterns of copy number variation in the Chinese yak genome

Background

Copy number variation (CNV) represents an important source of genetic divergence that can produce drastic phenotypic differences and may therefore be subject to selection during domestication and environmental adaptation. To investigate the evolutionary dynamics of CNV in the yak genome, we used a read depth approach to detect CNV based on genome resequencing data from 14 wild and 65 domestic yaks and determined CNV regions related to domestication and adaptations to high-altitude.

Results

We identified 2,634 CNV regions (CNVRs) comprising a total of 153 megabases (5.7 % of the yak genome) and 3,879 overlapping annotated genes. Comparison between domestic and wild yak populations identified 121 potentially selected CNVRs, harboring genes related to neuronal development, reproduction, nutrition and energy metabolism. In addition, we found 85 CNVRs that are significantly different between domestic yak living in high- and low-altitude areas, including three genes related to hypoxia response and six related to immune defense. This analysis shows that genic CNVs may play an important role in phenotypic changes during yak domestication and adaptation to life at high-altitude.

Conclusions

We present the first refined CNV map for yak along with comprehensive genomic analysis of yak CNV. Our results provide new insights into the genetic basis of yak domestication and adaptation to living in a high-altitude environment, as well as a valuable genetic resource that will facilitate future CNV association studies of important traits in yak and other bovid species.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-016-2702-6) contains supplementary material, which is available to authorized users.

Molecular detection and characterization of Theileria infection in cattle and yaks from Tibet Plateau Region, China

Theileriosis continues to threaten the livestock industry worldwide, but comprehensive epidemiological surveys for this disease have not been conducted in the Tibet Plateau Region, China. In this study, we screened 154 cattle blood samples from the Tibet Plateau Region (Lhasa, Lhoka, and Tianzhu), China, for detection of Theileria pathogens by polymerase chain reaction (PCR) with species-specific primers. The results revealed that the prevalence was 6.9 % (2/29) for Theileria orientalis and 27.6 % (8/29) for Theileria sinensis in Lhasa, 0 % (0/30) for T. orientalis and 26.7 % (8/30) for T. sinensis in Lhoka, and 0 % (0/95) for T. orientalis and 30.5 % (29/95) for T. sinensis in Tianzhu. Interestingly, Theileria luwenshuni, which was a previously reported pathogenic Theileria sp. in sheep and goats, was detected in blood samples from cattle and yaks for the first time, with a prevalence of 10 % (3/30) in Lhoka and 1.1 % (1/95) in Tianzhu. No other Theileria sp. was detected in these samples. T. sinensis and T. orientalis infections were detected in cattle and yaks, and T. luwenshuni was discovered for the first time in cattle and yaks in the Tibet Plateau Region, China.

Identification of piroplasm infection in questing ticks by RLB: a broad range extension of tick-borne piroplasm in China?

Sensitive and specific diagnostic method for rapid and simultaneous detection and discrimination of the different species is needed for an effective control of piroplasmosis. Here, a reverse line blot (RLB) assay was developed for piroplasm detection. A general pair of primer based on 18S ribosomal RNA (rRNA) gene was used to amplify V4 region of 18S rRNA gene. General and specific probes for 13 piroplasm species were cited from previous publications or designed according to the alignment of 18S rRNA gene sequences. For sensitivity test of RLB assay, serially diluted plasmids of the different species were used to access the sensitivity of the RLB. Four hundred and fifty tick samples collected from grass from different provinces of China were then detected. The result indicated that the RLB assay is highly specific and sensitive, detecting up to 10(2) copies/μl of recombinant plasmid DNA. Multiple piroplasms were detected as single or mixed infection from tick species. Eight piroplasm species, most of which were Theileria annulata (33/450, 7.3 %) or Babesia sp. Xinjiang (30/450, 6.7 %), were found to infect with 89 tick samples in four tick species; no infections with Babesia major, Babesia ovata, Babesia bigemina, Theileria sergenti, or Theileria equi were detected. The piroplasms species-specific RLB assay may have potential clinical application in the simultaneous detection and differentiation of Babesia and Theileria species.

Serologic Evidence for Babesia bigemina Infection in Wild Yak (Bos mutus) in Qinghai Province, China

Piroplasmosis, caused by tick-borne protozoan parasites of the genera Theileria and Babesia, is one of the most economically important infections of domestic ruminants in China. We evaluated the prevalence of antibodies to Babesia bigemina in wild yaks (Bos mutus) from Qinghai Province, China. Of 91 samples, 24% had detectable B. bigemina antibodies, and significant differences in prevalence were observed between those older than 5 yr and those younger than 5 yr. We collected 1,679 ticks belonging to two Ixodid genera from the infested wild yaks. The most prevalent tick species was Dermacentor nuttalli (48.1%), followed by Haemaphysalis qinghaiensis (33.3%) and Dermacentor silvarum (18.6%). These results indicated that B. bigemina is most likely endemic in the study area, and active surveillance programs for piroplasmosis are needed for monitoring animal health status.

Development of a multiplex PCR assay for detection and discrimination of Theileria annulata and Theileria sergenti in cattle

Aim to construct a simple and efficient diagnostic assay for Theileria annulata and Theileria sergenti, a multiplex polymerase chain reaction (PCR) method was developed in this study. Following the alignment of the related sequences, two primer sets were designed specific targeting on T. annulata cytochrome b (COB) gene and T. sergenti internal transcribed spacer (ITS) sequences. It was found that the designed primers could react in one PCR system and generating amplifications of 818 and 393 base pair for T. sergenti and T. annulata, respectively. The standard genomic DNA of both species Theileria was serial tenfold diluted for testing the sensitivity, while specificity test confirmed both primer sets have no cross-reaction with other Theileria and Babesia species. In addition, 378 field samples were used for evaluation of the utility of the multiplex PCR assay for detection of the pathogens infection. The detection results were compared with the other two published PCR methods which targeting on T. annulata COB gene and T. sergenti major piroplasm surface protein (MPSP) gene, respectively. The developed multiplex PCR assay has similar efficient detection with COB and MPSP PCR, which indicates this multiplex PCR may be a valuable assay for the epidemiological studies for T. annulata and T. sergenti.

Report of Theileria luwenshuni and Theileria sp. RSR from cervids in Gansu, China

Theileria parasites are important tick-borne pathogens of animals and cause huge economic losses worldwide. Here, we undertook to assess the prevalence of Theileria spp. in cervids in Gansu, China, based on PCR analysis and sequencing of the 18S rRNA genes. Molecular survey showed that Theileria luwenshuni and Theileria sp. RSR were frequently found in Gansu cervids, and the prevalence of T. luwenshuni was 66.7% (n = 9, 6/9) in roe deer in Zhengning County, 58.3% (n = 12, 7/12) in sika deer in Ningxian County, 50% (n = 10, 5/10) in sika deer and 42.9% (n = 14, 6/14) in red deer in Weiyuan County. The prevalence of Theileria sp. RSR was 77.8% (n = 9, 7/9) in roe deer in Zhengning County, 75% (n = 12, 9/12) in sika deer in Ningxian County, 60.0% (n = 10, 6/10) in sika deer, and 50.0% (n = 14, 7/14) in red deer in Weiyuan County. The co-prevalence of the two T. luwenshuni and Theileria sp. RSR was 55.6% (n = 5, 5/9) in roe deer in Zhengning County, 50% (n = 12, 6/12) in sika deer in Ningxian county, 50% (n = 10, 5/10) in sika deer and 35.7% (n = 14, 5/14) in red deer in Weiyuan County, respectively. No other Theileria species was found in these samples. T. luwenshuni and Theileria sp. RSR were detected for the first time in cervids in Gansu, China. Animal experiments showed that four sheep were inoculated with roe deer blood from Zhengning, sika deer blood from Ningxian, sika deer blood, and red deer blood from Weiyuan, respectively, and the Theileria isolated from these inoculated sheep was identified as T. luwenshuni, but Theileria sp. RSR was not detected in these sheep. Our results extend our understanding of the epidemiology of cervine theileriosis in Gansu, China, and will facilitate the implementation of measures to control theileriosis in cervids and small ruminants. This was the first report to demonstrate the occurrence of T. luwenshuni from roe deer, sika deer, and red deer worldwide.

A review of Theileria diagnostics and epidemiology

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Serological and molecular assays exist for most economic important Theileria species.

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Molecular assays are constantly being improved with regard to sensitivity and specificity.

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The concept of what constitute a Theileria species impacts on accurate diagnostics.

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Analytical specificity of molecular assays are >800 000 parasites/L blood.

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Parasitemia ranges may determine practical limits of detection.

An extensive range of serological and molecular diagnostic assays exist for most of the economically important Theileira species such as T. annulata, T. equi, T. lestoquardi, T. parva, T. uilenbergi and other more benign species. Diagnostics of Theileria is considered with regard to sensitivity and specificity of current molecular and serological assays and their use in epidemiology. In the case of serological assays, cross-reactivity of genetically closely related species reduces the use of the gold standard indirect fluorescent antibody test (IFAT). Development of antigen-specific assays does not necessarily address this problem, since closely related species will potentially have similar antigens. Even so, serological assays remain an important line of enquiry in epidemiological surveys. Molecular based assays have exploded in the last decade with significant improvements in sensitivity and specificity. In this review, the current interpretation of what constitute a species in Theileria and its impact on accurate molecular diagnostics is considered. Most molecular assays based on conventional or real-time PCR technology have proven to be on standard with regard to analytical sensitivity. However, consideration of the limits of detection in regard to total blood volume of an animal indicates that most assays may only detect >400,000 parasites/L blood. Even so, natural parasitaemia distribution in carrier-state animals seems to be above this limit of detection, suggesting that most molecular assays should be able to detect the majority of infected individuals under endemic conditions. The potential for false-negative results can, however, only be assessed within the biological context of the parasite within its vertebrate host, i.e. parasitaemia range in the carrier-state that will support infection of the vector and subsequent transmission.

Evolution and genetic diversity of Theileria

Theileria parasites infect a wide range of domestic and wild ruminants worldwide, causing diseases with varying degrees of severity. A broad classification, based on the parasite's ability to transform the leukocytes of host animals, divides Theileria into two groups, consisting of transforming and non-transforming species. The evolution of transforming Theileria has been accompanied by drastic changes in its genetic makeup, such as acquisition or expansion of gene families, which are thought to play critical roles in the transformation of host cells. Genetic variation among Theileria parasites is sometimes linked with host specificity and virulence in the parasites. Immunity against Theileria parasites primarily involves cell-mediated immune responses in the host. Immunodominance and major histocompatibility complex class I phenotype-specificity result in a host immunity that is tightly focused and strain-specific. Immune escape in Theileria is facilitated by genetic diversity in its antigenic determinants, which potentially results in a loss of T cell receptor recognition in its host. In the recent past, several reviews have focused on genetic diversity in the transforming species, Theileriaparva and Theileriaannulata. In contrast, genetic diversity in Theileriaorientalis, a benign non-transforming parasite, which occasionally causes disease outbreaks in cattle, has not been extensively examined. In this review, therefore, we provide an outline of the evolution of Theileria, which includes T. orientalis, and discuss the possible mechanisms generating genetic diversity among parasite populations. Additionally, we discuss the potential implications of a genetically diverse parasite population in the context of Theileria vaccine development.

Phylogeny of Theileria buffeli genotypes identified in the South African buffalo (Syncerus caffer) population

Theileria buffeli/orientalis is a group of benign and mildly pathogenic species of cattle and buffalo in various parts of the world. In a previous study, we identified T. buffeli in blood samples originating from the African buffalo (Syncerus caffer) in the Hluhluwe-iMfolozi Game Park (HIP) and the Addo Elephant Game Park (AEGP) in South Africa. The aim of this study was to characterise the 18S rRNA gene and complete internal transcribed spacer (ITS1-5.8S-ITS2) region of T. buffeli samples, and to establish the phylogenetic position of this species based on these loci. The 18S rRNA gene and the complete ITS region were amplified from DNA extracted from blood samples originating from buffalo in HIP and AEGP. The PCR products were cloned and the resulting recombinants sequenced. We identified novel T. buffeli-like 18S rRNA and ITS genotypes from buffalo in the AEGP, and novel Theileria sinensis-like 18S rRNA genotypes from buffalo in the HIP. Phylogenetic analyses indicated that the T. buffeli-like sequences were similar to T. buffeli sequences from cattle and buffalo in China and India, and the T. sinensis-like sequences were similar to T. sinensis 18S rRNA sequences of cattle and yak in China. There was extensive sequence variation between the novel T. buffeli genotypes of the African buffalo and previously described T. buffeli and T. sinensis genotypes. The presence of organisms with T. buffeli-like and T. sinensis-like genotypes in the African buffalo could be of significant importance, particularly to the cattle industry in South Africa as these animals might act as sources of infections to naïve cattle. This is the first report on the characterisation of the full-length 18S rRNA gene and ITS region of T. buffeli and T. sinensis genotypes in South Africa. Our study provides invaluable information towards the classification of this complex group of benign and mildly pathogenic species.

Detection of piroplasms infection in sheep, dogs and hedgehogs in Central China

BACKGROUND

Piroplasms are kinds of tick-borne parasitic apicomplexan protozoa, which are detrimental to humans and animals in tropical and subtropical areas around the world. Up until now, there has been a limited amount of reliable information available about the prevalence of piroplasms infections in wild animals in China. Therefore, we have investigated the infections of Babesia and Theileria species in both domestic and wild animals in Xinyang city, Henan province, where tick-borne diseases have recently been reported. This study aims to analyze the distribution patterns of piroplasms infections in animals, and assess their potential threat to humans in Central China.

METHODS

Blood samples were collected from sheep, dogs and hedgehogs in two regions, including Shihe District and Luoshan County, of Xinyang city, Henan province from August to December 2012. Babesia spp. and Theileria spp. were detected by polymerase chain reaction (PCR) and identified by sequencing and phylogenetic analysis. Moreover, the characteristics of detected piroplasms in different animal hosts were compared between the two study regions.

RESULTS

A total of 227 blood samples were collected from 73 sheep, two dogs and 152 hedgehogs. Babesia spp. was only detected in the two dogs. Theileria spp. was detected both in the sheep and the hedgehogs, and the total positive rate of Theileria spp. in the sheep and the hedgehogs was 57.53% and 13.82%, respectively. Sequencing and phylogenetic analysis revealed that the Theileria spp. detected in the sheep and the hedgehogs were very close to T. lunwenshuni cloned from a small ruminant and Theileria spp. isolated from a febrile hospitalized patient in China.

CONCLUSION

Babesia and Theileria infections were detected in both domestic and wild animals in Xinyang city, Henan province in Central China, thus warranting further studies in these regions.

Molecular identification of Theileria parasites of northwestern Chinese Cervidae

BACKGROUND

Theileria and Babesia protozoan parasites are transmitted mainly by tick vectors. These parasites cause heavy economic losses to the live-stock industry, as well as affecting the health of wild animals in parasite-endemic areas. Identification of infectious agents in wild animals is not only crucial for species preservation, but also provides valuable information on parasite epidemiology. Here, we conducted a molecular surveillance study in Northwestern China to assess the prevalence of blood pathogens in cervids.

METHODS

PCR analysis and microscopic evaluation of blood smears to detect Theileria- and Babesia-related diseases in Cervidae were conducted, in which 22 blood samples from red deer (n = 22) in Qilian Mountain and 20 from sika deer (n = 20) in Long Mountain were collected and tested for the presence of Theileria and Babesia. The 18S rRNA gene was amplified, and selected polymerase chain reaction (PCR)-positive samples were sequenced for species identification.

RESULTS

PCR revealed that 9.1% of the Qilian Mountain samples and 20% of the Long Mountain samples were positive for Theileria uilenbergi; 90.09% of the Qilian Mountain samples (n = 22) were positive for T. capreoli, but all of the Long Mountain samples (n = 20) were negative for T. capreoli; no other Theileria or Babesia species were found. PCR showed that T. uilenbergi and T. capreoli were present in red deer in Qilian Mountain, while only T. uilenbergi was found in sika Deer in Long Mountain. The 18S rRNA gene sequences were aligned against the corresponding GenBank sequences of known isolates of Theileria and Babesia and subjected to phylogenetic analysis. The phylogenetic tree showed that the newly isolated Theileria spp. could be classified as belonging to two clades: one group belonged to the same clade as T. uilenbergi, the other to a clade containing T. capreoli.

CONCLUSIONS

Our results provide important data to increase understanding of the epidemiology of Cervidae theileriosis, and will assist with the implementation of measures to control theileriosis transmission to Cervidae and small ruminants in central China.

Molecular prevalence and genetic diversity of bovine Theileria orientalis in Myanmar

Theileria orientalis is a causative agent of benign theileriosis in cattle and distributed in mainly Asian countries. In the present study, we examined the prevalence of T. orientalis infection by PCR based on the major piroplasm surface protein gene (MPSP) sequences in cattle in Myanmar, followed by phylogenetic analysis of the MPSP genes. The MPSP gene was amplified in 258 of 713 (36.2%) cattle blood DNA samples collected from five cities in different geographical regions of Myanmar. Phylogenetic analysis of MPSP sequences from 54 T. orientalis-positive DNA samples revealed the presence of six allelic genotypes, including Types 1, 3, 4, 5, 7, and N-3. Types 5 and 7 were the predominant types detected. Sequences of the MPSP genes detected in Myanmar were closely related to those from Thailand, Vietnam or Mongolia. These findings suggest that movement of animals carrying T. orientalis parasites between Southeast Asian countries could be a reason for the similar genotype distribution of the parasites in Myanmar.

Theileria infection in domestic ruminants in northern Ethiopia

Piroplasmosis caused by different tick-borne hemoprotozoan parasites of the genera Theileria and Babesia is among the most economically important infections of domestic ruminants in sub-Saharan Africa. A survey for piroplasm infection was conducted in three locations in Northern Ethiopia. Of 525 domestic ruminants surveyed, 80% of the cattle, 94% of the sheep and 2% of the goats were positive for different Theileria spp. based on PCR of blood followed by DNA sequencing. Sheep had a significantly higher rate of infection compared with cattle (P<0.0003) and both sheep and cattle had higher rates of infection compared to goats (P<0.0001). Four species of Theileria were detected in cattle: T. velifera, T. mutans, T. orientalis complex and T. annulata with infection rates of 66, 8, 4, and 2%, respectively. This is the first report of T. annulata, the cause of Tropical Theileriosis in Ethiopia. Of the two Theileria spp. detected in small ruminants, T. ovis was highly prevalent (92%) in sheep and rare in goats (1.5%) whereas T. seperata was infrequent in sheep (2%) and rare in goats (0.4%). None of the animals were positive for Babesia spp.; however, Sarcocystis capracanis and S. tenella were detected in one goat and a sheep, respectively. The widespread distribution of Theileria spp. among cattle in northern Ethiopia including the virulent T. annulata and more mildly pathogenic T. mutans and T. orientalis, and the high infection rate in sheep with the usually sub-clinical T. ovis indicate extensive exposure to ticks and transmission of piroplasms with an important economic impact.

RPS8--a new informative DNA marker for phylogeny of Babesia and Theileria parasites in China

Piroplasmosis is a serious debilitating and sometimes fatal disease. Phylogenetic relationships within piroplasmida are complex and remain unclear. We compared the intron–exon structure and DNA sequences of the RPS8 gene from Babesia and Theileria spp. isolates in China. Similar to 18S rDNA, the 40S ribosomal protein S8 gene, RPS8, including both coding and non-coding regions is a useful and novel genetic marker for defining species boundaries and for inferring phylogenies because it tends to have little intra-specific variation but considerable inter-specific difference. However, more samples are needed to verify the usefulness of the RPS8 (coding and non-coding regions) gene as a marker for the phylogenetic position and detection of most Babesia and Theileria species, particularly for some closely related species.

Phylogenetic analysis of ruminant Theileria spp. from China based on 28S ribosomal RNA gene

Species identification using DNA sequences is the basis for DNA taxonomy. In this study, we sequenced the ribosomal large-subunit RNA gene sequences (3,037-3,061 bp) in length of 13 Chinese Theileria stocks that were infective to cattle and sheep. The complete 28S rRNA gene is relatively difficult to amplify and its conserved region is not important for phylogenetic study. Therefore, we selected the D2-D3 region from the complete 28S rRNA sequences for phylogenetic analysis. Our analyses of 28S rRNA gene sequences showed that the 28S rRNA was useful as a phylogenetic marker for analyzing the relationships among Theileria spp. in ruminants. In addition, the D2-D3 region was a short segment that could be used instead of the whole 28S rRNA sequence during the phylogenetic analysis of Theileria, and it may be an ideal DNA barcode.

Molecular detection of Theileria species in sheep from northern China

Ovine theileriosis is a tick-borne disease that restricts the development of small ruminant husbandry in northern China. In this study, we report on a molecular epidemiological survey of ovine Theileria spp. in 198 blood samples taken from sheep in northern China. The DNA samples were screened by a nested polymerase chain reaction (PCR) targeting the 18S rRNA gene of ovine Theileria spp. The prevalence of ovine Theileria spp. in Yanji, Nongan, Longjing, Toudao and Jinchang was 80%, 40%, 37%, 24% and 32%, respectively. The sequencing analyses approved the present of the T. orientalis and/or T. luwenshuni in these regions. Taken together, we have demonstrated a high incidence of Theileria spp. in northern China that calls for the need to design effective control programs for ovine theileriosis.

Phylogenetic analysis based on 28S rRNA of Babesia spp. in ruminants in China

Molecular phylogenetic analyses are mainly based on the small ribosomal RNA subunit (18S rRNA), internal transcribed spacer regions, and other molecular markers. We compared the phylogenetic relationships of Babesia spp. using large subunit ribosomal RNA, i.e., 28S rRNA, and the united 28S + 18S rRNA sequence fragments from 11 isolates of Babesia spp. collected in China. Due to sequence length and variability, the 28S rRNA gene contained more information than the 18S rRNA gene and could be used to elucidate the phlyogenetic relationships of B. motasi, B. major, and B. bovis. Thus, 28S rRNA is another candidate marker that can be used for the phylogenetic analysis of Babesia spp. However, the united fragment (28S + 18S) analysis provided better supported phylogenetic relationships than single genes for Babesia spp. in China.

A DNA barcode for Piroplasmea

Due to the difficulty in morphological identification the development of reliable molecular tools for species distinction is a priority for piroplasma. Previous studies based on 18S rRNA and other gene sequences provided a backbone for the phylogeny of piroplasma. However, it is difficult to discriminate species in a comprehensive sample. Here, the abilities of eight DNA regions including 18S rRNA, 28S rRNA, internal transcribed spacer (ITS) regions and COI genes, have been compared as candidates of DNA barcodes for piroplasma. In total, 484 sequences of piroplasma were collected from this study and GenBank. The eight proposed DNA regions were evaluated according to the criterion of Consortium for the Barcode of Life (CBOL). From this evaluation, ITS2 had 100% PCR amplification efficiency, an ideal sequence length, the largest gap between the intra- and inter-specific divergence, 98% identification efficiency at the genus level, and 92% at the species level. Thus, we propose that ITS2 is the most ideal DNA barcode based on the current database for piroplasma.

Rapid identification and differentiation of Theileria sergenti and Theileria sinensis using a loop-mediated isothermal amplification (LAMP) assay

The present study developed and validated a species-specific loop-mediated isothermal amplification (LAMP) assay for the rapid detection and discrimination of two benign bovine Theileria species -T. sergenti and T. sinensis. The LAMP assay is inexpensive and easy to perform and involves a rapid reaction-the amplification can be performed in 55 min or 50 min under isothermal conditions of 61°C or 63°C, respectively, by employing a set of four species-specific primer mixtures. The results can be checked using agarose gels. The optimal assay conditions, under which the assay exhibited with no cross-reaction with other closely related tick-borne parasites (T. annulata, Babesia bovis, B. bigemina, B. major, B. ovata, B. U. sp., Anaplasma marginale) or between the two Theileria species of interest, was established. The assay is approximately 10-fold more sensitive than the conventional specific PCR assay. The LAMP assay was validated using DNA from 6 standard stocks in the laboratory and was evaluated for its diagnostic utility using blood samples collected from experimentally and naturally infection cattle or yaks in China. These findings indicate that this Theileria species-specific LAMP assay may have potential clinical applications for the detection and differentiation of two benign bovine Theileria species -T. sergenti and T. sinensis, especially in endemic countries.

Phylogenetic analysis of benign Theileria species based on major piroplasm surface protein (MPSP) genes from ticks of grazing cattle in Korea

Complete major piroplasm surface protein (MPSP) gene sequences of benign Theileria parasites were isolated from ticks of grazing cattle in Korea. A total of 556 tick samples were collected in five provinces: Chungbuk, Jeonbuk, Jeonnam, Gyeongbuk, and Jeju during 2010-2011. Fifteen samples from Chungbuk and Jeonnam were positive for the Theileria MPSP gene by PCR amplification using a specific primer set. A phylogenetic tree was constructed with the amplified gene sequences and 26 additional sequences published in GenBank. The benign Theileria parasites were classified into eight types, those isolated from Korean cattle ticks belonged to Types 1 (Ikeda), 2 (Chitose), 4, and 8. Types 2 and 4 were the most common types, with the rate of 40%, followed by Types 1 and 8 (with the rate of 13% and 7%, respectively). Nucleotide sequence identities of 23 theilerial MPSP sequences (15 MPSP gene sequences amplified and 8 sequences published) ranged from 67.3 to 99.8%. Multiple alignments of the deduced amino acid sequences also showed that each type was characterized by specific amino acids: 7 for Type 1, 9 for Type 2, 4 for Type 4, and 3 for Type 8.

Simultaneous detection of piroplasma infections in field Haemaphysalis qinghaiensis ticks by reverse line blotting

Piroplasmosis is caused by tick-borne haemoprotozoan parasites in the genera of Theileria and Babesia, in which numbers of agents are highly pathogenic for cattle, sheep and goats. We developed a reverse line blot (RLB) assay for detection and differentiation of four different parasites, in which 18S ribosomal RNA gene sequence was amplified with a set of universal primers specific for all members in the genera of Theileria and Babesia; and the probes were designed on the basis of hypervariable region 4 (V4 region) of 18S rRNA gene. Three Theileria and one Babesia can be detected simultaneously on this system and it was sensitive to detect a parasitemia level between 10(-5) and 10(-8)%. A total of 149 Haemaphysalis qinghaiensis ticks collected from Lintan County of Gannan Tibetan Autonomous Region was tested by RLB. Among these, 136 tick samples were also tested by a nested PCR assay developed previously. After comparison of these results, it showed that more T. luwenshuni was detected in RLB assay, while more T. uilenbergi was detected in H. qinghaiensis ticks by nested PCR. The RLB has shown capability for simultaneous detection of four species of piroplasm in H. qinghaiensis ticks, indicating its usefulness for epidemiological studies of piroplasmosis.

Molecular prevalence of different genotypes of Theileria orientalis detected from cattle and water buffaloes in Thailand

Here we report on an epidemiological study regarding the molecular prevalence of different genotypes of Theileria orientalis present among domestic cattle and water buffalo populations bred in Thailand. A phylogenetic analysis based on the parasitic gene encoding a major piroplasm surface protein revealed the presence of 5 genotypes (Types 1, 3, 5, 7, and N-3) in cattle and 7 genotypes (Types 1, 3, 4, 5, 7, N-2, and N-3) in water buffaloes. Types 4, 7, and N-3 of T. orientalis were reported for the first time in water buffaloes. The previously reported C and Thai types from Thailand clustered as types 7 and 6, respectively, in the present analysis. Great similarities were observed among nucleotide sequences of isolates of the same genotype from cattle and water buffaloes, and, therefore, water buffaloes were considered to serve as a reservoir for these genotypes of T. orientalis in Thailand. In conclusion, T. orientalis parasites circulating in Thailand are more diverse in their genetic characters than previously anticipated.

The first survey of Theileria orientalis infection in Mongolian cattle

In the present study, we have surveyed the presence of a bovine Theileria protozoan, Theileria orientalis, in Mongolian cattle and engorging tick populations from selected provinces and districts in Mongolia. The percentages of infection in the cattle and ticks ranged from 8.8 to 66.6 and from 3.7 to 73.3, respectively, on a per district basis. The genetic diversity of T. orientalis isolates was also studied, based on the protozoan gene encoding a major piroplasm surface protein (MPSP). At least five genotypes (types 1, 3, 5, 7, and N-3) of T. orientalis were found to be circulating among the Mongolian cattle and tick populations. In particular, types 3 and N-3 were common in most of the districts examined, while a strong geographical relationship among the genotypes was not detected in the present study. This is the first epidemiological report describing the presence of T. orientalis infection in Mongolian cattle.