Detection and differentiation of ovine Theileria and Babesia by reverse line blotting in China

Molecular detection and characterization of Anaplasma ovis, Theileria ovis, and Theileria lestoquardi in sheep and goats in Luxor, Egypt

BACKGROUND

Tick-borne diseases cause economically significant losses to animal production globally, and anaplasmosis and theileriosis are associated with the greatest losses. However, the spread of the relevant pathogens in flocks of domesticated animals in southern Egypt is little understood. Accordingly, in this study, we aimed to determine the prevalences of Anaplasma ovis, Theileria ovis, and Theileria lestoquardi in southern Egyptian sheep and goats through blood tests, and to make a molecular characterization of the A. ovis detected in sheep targeting a specific gene.

RESULTS

We collected blood samples collected from 300 sheep and goats (n=150 /species) in Luxor Province in southern Egypt, and analyzed them for the presence of A. ovis, T. ovis and T. lestoquardi with screening by conventional and nested PCR targeting the msp4 and msp5, 18S rRNA, and merozoite surface protein genes. For A. ovis 140/300 samples (46.66%) were positive overall, with 90/150 (60%) and 50/150 (33.33%) positive samples in sheep and goats, respectively. Two major surface protein genes of A. ovis, msp4 and msp5, were sequenced using DNA extracted from sheep and goat blood samples, for phylogenetic analysis and genotyping. The msp4 gene sequence revealed no significant genetic diversity, to contrast to data on A. ovis strains from other countries. For T. lestoquardi, 8/150 (5.33%) samples were positive in sheep, but no samples were positive in goats (0%). For T. ovis, 32/150 (21.33%) samples were positive in sheep, but no samples were positive in goats (0%). Sequencing targeting the merozoite surface protein gene for T. lestoquardi and the small subunit ribosomal RNA gene for T. ovis revealed no significant genetic diversity in the study, another contrast to data on A. ovis strains from other countries.

CONCLUSION

This study provides valuable data on phylogenetic and molecular classifications of A. ovis, T. ovis and T. lestoquardi found in southern Egyptian sheep and goats. It also represents the first report on detection and molecular characterization of T. lestoquardi in southern Egyptian sheep based on the specific merozoite surface protein gene, thus providing valuable data for molecular characterization of this pathogen in southern Egypt.

Identification, molecular characterization and risk factors of Theileria infection among sheep: a first comprehensive report from North India

The present study was aimed at the identification, molecular characterization, and risk factor assessment of Theileria infection among sheep of Haryana province, north India. A total of 402 blood samples were collected from three different climatic zones of Haryana from March 2020 to September 2021. Light microscopy of blood smears revealed Theileria spp. infection in 47.26% (n = 190), while 60.94% (n = 245) of blood samples were positive using nested PCR. Extensive molecular characterization of Theileria infection using four pairs of species-specific primers indicated the dominance of T. ovis (29.1%) followed by T. lestoquardi (12.69%), T. luwenshuni (5.97%) and T. annulata (1.49%). Mixed infection was detected in 11.69% of cases. Bidirectional sequencing and phylogeny further confirmed the presence of these four Theileria spp. in the investigated area under study. Hematology indicated a significant (p < 0.01) reduction in various haematological indices of animals infected with T. luwenshuni and T. lestoquardi compared to the healthy control group. Risk factors like age, sex, and zone were significantly associated with Theileria infection in sheep. The present investigation depicts the first comprehensive molecular report of ovine Theileria spp., which warrants further study to develop suitable control strategies against these haemoparasitic infections.

Molecular identification and genetic characterization of Theileria and Anaplasma infection in sheep and goat of North Gujarat, India

Hemoprotozoal diseases are significant health concerns in small ruminants. The present study was conducted to identify and characterize the species of Theileria and Anaplasma in sheep and goats located in different districts of North Gujarat, India. A total of 226 (Banaskantha = 175, Patan = 26, and Bhuj = 25) blood samples were collected from sheep (n = 78) and goats (n = 148), and 46 ticks were collected and identified from sheep and goats. PCR assays were carried out using genus and species-specific primers for Theileria targeting 18S rRNA locus and for Anaplasma targeting the msp5 gene. Overall, 37.2% sheep (29/78) and 10.8% of goats (16/148) were positive for Theileria by PCR, whereas 15.4% of sheep (12/78) and 25.7% goats (38/148) were positive for Anaplasma infection. Moreover, mixed infection was found in 4.4% (10/226) of sheep and goats by PCR. Sanger sequencing of Theileria and Anaplasma positives revealed a high similarity to T. ovis and A. ovis using NCBI blast, respectively. Phylogenetic analyses revealed that the Anaplasma spp. DNA sequences belonged to the A. ovis group and closely associated with the A. ovis nucleotide sequence strain Haibei isolated in China from sheep (GQ483471). The phylogenetic analysis based on the SSU rRNA locus revealed that the Theileria ovis DNA sequences belonged to the T. ovis group and closely related to MW440586 isolated in Kerala, India, from a goat. The majority of ticks (91.3%) were identified as Hyalomma. In conclusion, Theileria ovis and Anaplasma ovis were commonly identified species in sheep and goats and transmitted mainly by Hyalomma ticks in North Gujarat, India, which is important baseline data for future research and control strategies. This is the first report on Theileria and Anaplasma co-infections in sheep and goats from North Gujarat, India.

Anaemia in Sheep Caused by Babesia and Theileria Haemoparasites

Piroplasmoses in sheep are caused by vector-borne apicomplexan protozoa, Babesia and Theileria. Different species are responsible for the disease; some species are more pathogenic than others and have a worldwide distribution. In this sense, these causative agents can cause anaemia in flocks. In general, these vector-borne diseases infect small ruminants and cause host-mediated pathology. In the case of Babesia species, a combination of different mechanisms is involved: red blood cell lysis due to intracellular parasite multiplication, activation of biogenic amines and the coagulation system with the possibility of disseminated intravascular coagulation. By contrast, less information is available on the different immunopathogenic mechanisms involved in the development of anaemia in sheep with theileriosis. However, the mechanisms of pathogenic action in theileriosis are similar to those studied in babesiosis. Diagnosis is based on compatible clinical signs, laboratory findings, specific diagnostic tests and the presence of the tick vector. Some of these tests detect the causative agent itself, such as direct identification by light microscopy and molecular analysis. In contrast, other tests detect the sheep's immune response to the organism by serology. Both diseases pose a significant diagnostic challenge for veterinary practitioners around the world. This review presents the most frequent clinical signs, pathogenesis and clinicopathological findings, diagnosis.

Molecular Detection and Differentiation of Different Theileria Species in Naturally Infected Goats Using Nested PCR-RFLP: A First Report from Northern India

PURPOSE

Theileriosis is an economically important tick-borne pathogen with a serious impact on livestock health and productivity. Despite the fact that bovine theileriosis has been widely investigated, there exists a paucity of information on these infections in small ruminants, especially in India. The present study was carried out to detect and differentiate different Theileria spp. in goats using nested PCR RFLP.

METHODS

Blood samples and ticks were collected from 405 goats in various agro-climatic zones of Haryana state, India. The blood samples were screened by microscopy, nested PCR-RFLP, and sequence analysis. The nested PCR-RFLP was performed with four restriction enzymes viz., Hpa II, Bsh 1285I, Hae II and Rsa I. Six nested PCR amplicons with different RFLP patterns were sequenced and submitted to NCBI (OM666861, MZ220430, OM666628, MZ220437, OM666637, OM721806).

RESULTS

Microscopy revealed 18.27% (n = 74) infection with Theileria spp., while 33.58% (n = 136) of blood samples were confirmed positive by nested PCR. Out of 136 positive samples, 43.38% (n = 59), 11.02% (n = 15) and 20.58% (n = 28), were positive for T. ovis, T. lestoquardi and T. luwenshuni (Theileria sp. China 1), respectively. Mixed infection was detected in 25% (n = 34) cases. Based upon Hpa II digestion pattern, 13 samples with T. lestoquardi and T. ovis, and 21 samples with T. ovis and T. luwenshuni were detected. Sequence study further confirmed their identity. The majority of ticks collected from goats were identified as Rhipicephalus spp., Hyalomma anatolicum and Hemaphysalis spp.

CONCLUSION

This study represents the first confirmed molecular report of goats infected with T. ovis, T. lestoquardi, and T. luwenshuni from northern India.

Prevalence of Theileria/Babesia Species in Ruminants in Burdur Province of Turkey

PURPOSE

Theileriosis and babesiosis, two tick-borne haemoparasitic diseases (TBHDs) of ruminants, are caused by protozoan parasites of the genus Theileria and Babesia, respectively. Among them, some species are considered to be highly pathogenic causing serious economic losses to livestock holders especially in tropic and subtropic regions. Local and/or general control measures are needed to be applied to reduce economic impact of TBHDs. Prevalence studies are essential for the implementation and/or design of effective prevention and control measures based on true epidemiological data. Therefore, this study aimed to investigate the presence, prevalence and possible cross infections of Theileria/Babesia species between sheep, goat and cattle herds in Burdur province in Turkey.

METHODS

A total of 964 blood samples were collected from sheep (n = 330), goat (n = 300) and cattle (n = 334) from five different districts of Burdur province. The samples were investigated for ovine and bovine Theileria/Babesia species using reverse line blot (RLB) hybridization assay.

RESULTS

In small ruminants, T. ovis was the most abundant Theileria species detected in sheep with a rate of 79.69%. Among Babesia species, B. ovis and B. crassa were detected only in blood of goats (0.66%) and sheep (1.12%) as single and mixed infections, respectively. In cattle, T. annulata, B. bovis, Babesia spp. were detected in rates of 0.59%, 3.29%, 3.59%, respectively.

CONCLUSION

Obtained results clearly indicated that no cross infections with Theileria/Babesia species occurred in small ruminant and cattle herds that use the same grazing area.

Molecular identification of Theileria species in naturally infected sheep using nested PCR-RFLP

Ovine theileriosis is an important tick-borne haemoprotozoan disease of sheep in tropical and subtropical regions, causing severe productivity and economic loss. There is a paucity of information related to molecular studies of ovine theileriosis from India. The present study identified different Theileria spp. in naturally infected sheep using nested PCR-restriction fragment length polymorphism (nPCR-RFLP). Blood samples and ticks were collected from 204 sheep in different agro-climatic zones of Haryana state, India, during the tick active season. Microscopic examination of thin blood smears revealed 33.3% (68/204) infections with Theileria spp., while 44.6% (91/204) of blood samples were positive by nPCR assay. Different Theileria spp. were identified based upon RFLP patterns using four restriction enzymes: Hpa II, Bsh 1285I, Hae II and Rsa I. Out of 91 positive samples, 50.5% (46/91), 23.08% (21/91), 11% (10/91) and 2.2% (2/91) were positive for T. ovis, T. lestoquardi, T. luwenshuni (Theileria sp. China 1/Theileria sp. China) and T. annulata, respectively. Mixed infection was detected in 13.2% (12/91) of cases. Based upon HpaII enzymatic digestion pattern, two samples with T. lestoquardi and T. annulata, nine samples with T. lestoquardi and T. ovis and one sample with T. ovis and T. annulata were detected. The presence of these Theileria spp. was further confirmed by sequence analysis. The majority of ticks collected from sheep were identified as Rhipicephalus spp. followed by Hyalomma anatolicum and Hemaphysalis spp. The present investigation depicts the first comprehensive molecular report of naturally infected sheep with T. ovis, T. lestoquardi, T. annulata and T. luwenshuni from northern India.

Mitochondrial genome of Theileria uilenbergi endemic in sheep and goats in China

Mitochondrial genomes provide new insights that help elucidating biological features, genetic evolution, and classification of protozoans. Theileria uilenbergi (T. uilenbergi), transmitted by Haemaphysalis qinghaiensis and H. longicornis, is considered as highly pathogenic to sheep and goats in China. This study reports and outlines features of its mitochondrial genome. The T. uilenbergi mitochondrial genome is a linear monomeric molecule of 6.0 kb length, which encodes three protein-coding genes named cytochrome c oxidase I (cox1), cytochrome b (cob), and cytochrome c oxidase III (cox3), as well as six large subunit (LSU) rRNA gene fragments, and ends in terminal inverted repeats (TIRs). The array structure and organization of the mitochondrial genome of T. uilenbergi is identical to that of T. parva. Phylogenetic analysis based on the amino acid sequences of cox1, cob, and cox3 genes suggests that T. uilenbergi is distantly related to the group of transforming Theileria species such as T. parva. This study contributes to a comprehensive understanding of the phylogeny and evolution of the mitochondrial genome of piroplasms and provides useful information of diagnostic marker for T. uilenbergi.

Molecular detection and prevalence of Theileria ovis and Anaplasma marginale in sheep blood samples collected from Layyah district in Punjab, Pakistan

Theileria ovis and Anaplasma marginale are intracellular pathogens affecting a wide range of animals, causing huge economic losses worldwide. The present study reports the molecular evidence of Theileria ovis and Anaplasma marginale in sheep blood samples (N = 218) collected from Layyah district in Punjab (Pakistan), where economy heavily relies on livestock. A 520 base pair fragment specific for 18S ribosomal RNA gene of Theileria ovis was PCR amplified in 23/218 (10.6%) sheep blood samples, while for Anaplasma marginale, a 265 base pair fragment specific for msp1b gene was generated in 15/218 (6.9%) sheep blood samples. Two blood samples were found co-infected (0.9%) with both parasites. Amplified PCR products of both parasites were confirmed by DNA sequencing and submitted to GenBank. Prevalence of both Theileria ovis (p = 0.3) and Anaplasma marginale (p = 0.4) varied non-significantly among the investigated sheep breeds. Tick burden on dogs present with sheep herds was found associated with Theileria ovis infection in sheep (p = 0.05). It was observed that lambs (p = 0.009), sheep in small herds (p = 0.04), and tick burden on dogs present with sheep herds (p = 0.01) were associated with Anaplasma marginale infection in sheep during the present study. In conclusion, we are reporting a higher prevalence of Theileria ovis than Anaplasma marginale in blood samples of sheep collected from Layyah district. Tick-infested dogs were found to be risk factors for the transmission of both pathogens in sheep, and tick control strategies should be extended to dogs associated with sheep herds in this area.

Rapid detection of Babesia motasi responsible for human babesiosis by cross-priming amplification combined with a vertical flow

Background

Babesia motasi is known as an etiological agent of human and ovine babesiosis. Diagnosis of babesiosis is traditionally performed by microscopy, examining Giemsa-stained thin peripheral blood smears. Rapid detection and accurate identification of species are desirable for clinical care and epidemiological studies.

Methods

An easy to operate molecular method, which requires less capital equipment and incorporates cross-priming amplification combined with a vertical flow (CPA-VF) visualization strip for rapid detection and identification of B. motasi.

Results

The CPA-VF targets the 18S rRNA gene and has a detection limit of 50 fg per reaction; no cross reaction was observed with other piroplasms infective to sheep or Babesia infective to humans. CPA-VF and real-time (RT)-PCR had sensitivities of 95.2% (95% confidence interval, CI 78.1–99.4%) and 90.5% (95% CI 72–97.6%) and specificities of 95.8 (95% CI 80.5–99.5%) and 97.9 (95% CI 83.5–99.9%), respectively, versus microscopy and nested (n) PCR combined with gene sequencing. The clinical performance of the CPA-VF assay was evaluated with field blood samples from sheep (n = 340) in Jintai county, Gansu Province, and clinical specimens (n = 492) obtained from patients bitten by ticks.

Conclusions

Our results indicate that the CPA-VF is a rapid, accurate, nearly instrument-free molecular diagnostic approach for identification of B. motasi. Therefore, it could be an alternative technique for epidemiological investigations and diagnoses of ovine and/or human babesiosis caused by B. motasi, especially in resource-limited regions.

Molecular detection of tick-borne pathogens harbored by ticks collected from livestock in the Xinjiang Uygur Autonomous Region, China

Ticks carry and transmit a wide range of pathogens (bacteria, viruses, and protozoa) that are of importance to humans and animals globally. However, information about the tick-borne pathogens harbored by ticks in the Xinjiang Uygur Autonomous Region (XUAR), northwestern China, is scarce. This study investigated the occurrence of tick species of domestic animals and tick-borne pathogens by using morphological molecular identification and sequence analysis in Turpan, Qitai, Altay, Hejing, Nileke, and Zhaosu counties (XUAR). A total of 5822 adult ticks (females and males) from 12 tick species were identified from 5 animal species (cattle, goats, sheep, camels, and horses) in 6 counties in the XUAR. Collected tick species included Dermacentor marginatus (24.7 %), Dermacentor nuttalli (20.8 %), Hyalomma anatolicum (13.7 %), Dermacentor niveus (13.1 %), Haemaphysalis punctata (10.7 %), Dermacentor silvarum (7.1 %), Dermacentor pavlovskyi (3.9 %), Hyalomma asiaticum (2.2 %), Rhipicephalus pumilio (1.9 %), Rhipicephalus sanguineus sensu lato (0.7 %), Rhipicephalus turanicus (0.6 %), and Hyalomma asiaticum kozlovi (0.6 %). Furthermore, 750 partially engorged adult ticks (females and males), including H. anatolicum (250), D. nuttalli (250), and D. marginatus (250), were individually separated according to species and sampling site, used for DNA extraction, and then screened for tick-borne pathogens. The most common pathogen was Rickettsia raoultii (36.80 %), followed by Brucella sp. (26.2 %), Anaplasma ovis (22.4 %), Babesia caballi (14.8 %), Theileria equi (8.7 %), and Theileria ovis (8.5 %). The sequencing of 6 genes showed a 96-100 % nucleotide identity between the sequences in this study and those deposited in GenBank. This study provides a scientific reference for the prevention and control of tick-borne diseases in the XUAR.

Molecular Characterization and Phylogenetic Analysis of Theileria spp. and Babesia spp. Isolated from Various Ticks in Southeastern and Northwestern Regions of Iran

INTRODUCTION

Piroplasms are hemoprotozoa comprising heterogeneous tick-borne parasites, which are differentiated into three genera, namely Babesia, Theileria, and Cytauxzoon. The aim of this study was to determine the prevalence, molecular identification, and phylogenetic relationship of both Theileria spp. and Babesia spp. in tick species isolated from different domestic animals from two different geographical locations of Iran.

MATERIALS AND METHODS

A total of 930 ticks collected from goats, sheep, and cattle were examined for the presence of Theileria spp. and Babesia spp. using PCR targeting 18S rRNA gene followed by sequencing. Sequence analysis was performed based on the data published in the GenBank on Theileria spp. and Babesia spp. isolates using bioinformatic tools, such as the standard nucleotide BLAST.

RESULTS

A 390 or 430 base pair fragment of 18S rRNA gene of Theileria and Babesia species was successfully amplified in 17.2% of the examined ticks (16of 93). Genome of Theileria or Babesia species was detected in 4 ticks collected in Heris, including 3 Dermacentor marginatus and 1 Rhipicephalus sanguineus, and also in 12 ticks collected in Chabahar, including 10 R. sanguineus and 2 D. marginatus. Partial analysis of 18S rRNA gene sequence of the four D. marginatus, collected from goats and sheep in Heris, showed that they were infected with Theileria spp. that were 95-97% identical to Iranian Theileria ovis present in the GenBank database (GenBank acc. no. KP019206.1). While the five R. sanguineus, collected from sheep and goats in Chabahar, were infected with Babesia spp. that were 91-97% identical to Iranian Babesia ovis present in the GenBank database (GenBank acc. no. AY362829.1: KT587794.1).

CONCLUSION

The prevalence of Babesia and Theileria is different in southeastern and northwestern parts of Iran, with higher prevalence of babesiosis in the southeastern region and that of theileriosis in the northwestern region. Sequence analysis of 18S rRNA gene revealed that T. ovis and B. ovis are genetically polymorphic in these regions.

Diagnostic tools of caprine and ovine anaplasmosis: a direct comparative study

Background

The diagnosis of anaplasmosis is rather conflicting with other haemoprotozoans. Hence, the study aimed to compare and evaluate the efficiency of competitive ELISA (cELISA), indirect fluorescence antibody (IFA), and Polymerase chain reaction (PCR) for precise diagnosis of Anaplasma spp. and to assess their concordance with microscopic examination (ME).

Results

A total of 312 blood samples (189 sheep and 123 goats) were examined for Anaplasma infection during a 1 year period. Giemsa-stained blood smears were examined under the microscope. IFA and cELISA were used for the detection of Anaplasma spp. antibodies. PCR was used as a standard of truth and for the identification of Anaplasma species. Using cELISA assay, 47.4% (148) were positive (93 sheep and 55 goats) with a sensitivity and specificity of 91.9, and 86.9%, respectively. Using IFA, it was found that 57.4% (179)were positive (113 sheep and 66 goats) with a sensitivity and specificity of 100, and 93.3%, respectively. PCR assay identified A. ovis in 49 (25.3%) sheep and 30 (15.5%) goats, and A. phagocytophilumin 74 (38.1%) sheep and 41 (20.8%) goats.

Conclusions

High sensitivity and specificity values of IFA and ELISA tests compared to microscopic examination strongly support their utility in the diagnosis of Anaplasma infection. PCR was a more specific diagnostic tool that allows to discriminate between Anaplasma subspecies, which makes it the method of choice for anaplasmosis diagnosis.

Prevalence of tick-borne haemoparasites in small ruminants in Turkey and diagnostic sensitivity of single-PCR and RLB

Background

Tick-borne haemoparasitic diseases (TBHDs), caused by Theileria, Babesia, Anaplasma and Ehrlichia, are common in regions of the world where the distributions of host, pathogen and vector overlap. Many of these diseases threaten livestock production and some also represent a concern to human public health. The primary aim of this study was to determine the prevalence of the above-mentioned pathogens in a large number of blood samples (n = 1979) collected from sheep (n = 1727) and goats (n = 252) in Turkey. A secondary aim was to assess the diagnostic sensitivity of a number of species-specific polymerase chain reaction (PCR) tests and the reverse line blotting (RLB) assay. DNA samples were screened using species-specific PCR for the presence of Theileria ovis, Theileria sp. MK, T. lestoquardi, T. uilenbergi, T. luwenshuni, Babesia ovis, Anaplasma ovis and A. phagocytophilum while RLB was undertaken to test for the presence of all known Theileria, Babesia, Anaplasma and Ehrlichia species. The diagnostic sensitivity of these two approaches was then compared in terms of their ability to detect single species and mixed infections.

Results

Overall, 84 and 74.43% of the small ruminants sampled were identified as hosting one or more pathogen(s) by species-specific PCR and RLB respectively. The presence of Theileria sp. OT1, T. luwenshuni and T. uilenbergi in Turkey was revealed for the first time while the presence of Babesia motasi, B. crassa and T. separata in Turkish small ruminants was confirmed using molecular methods. A high prevalence of mixed infection was evident, with PCR and RLB approaches indicating that 52.24 and 35.42% of animals were co-infected with multiple species, respectively. More than 80% of the mixed infections contained T. ovis and/or A. ovis. The RLB approach was found to be capable of detecting mixed infections with species such as Theileria sp. OT1, Theileria sp. OT3, T. separata, B. crassa and Babesia spp.

Conclusion

The results indicated that pathogens causing TBHDs are highly prevalent in sheep and goats in Turkey. The diagnostic sensitivity of species-specific single PCR was generally higher than that of RLB. However, the latter approach was still capable of identifying a high proportion of individuals containing mixed-species infections. The use of species-specific single PCR is recommended to accurately estimate pathogen prevalence and to identify co-infected hosts.

Electronic supplementary material

The online version of this article (doi:10.1186/s13071-017-2151-3) contains supplementary material, which is available to authorized users.

Important hemoprotozoan diseases of livestock: Challenges in current diagnostics and therapeutics: An update

Hemoprotozoan parasites pose a serious threat to the livestock population in terms of mortality, reduced milk yield and lowered draft power. Diagnosis of these diseases often poses a challenging task. Needless to say that impact of disease in health and productivity is huge though a fair economic assessment on the quantum of economic loss associated is yet to be worked out from India. The diagnosis of hemoprotozoan infections largely depends on various laboratory-based diagnostic methods as the clinical manifestations are often inconspicuous and non-specific. Traditional diagnostic methods rely on microscopical demonstration of infective stages in blood or tissue fluids. However, it is laborious, lesser sensitive, and cannot differentiate between morphologically similar organisms. Recent development in the technologies has opened new avenues for improvement in the accurate diagnosis of parasitic infections. Serological tests are simple, fast but lack specificity. With advent of molecular techniques, as DNA hybridization assays, polymerase chain reaction and its modifications ensure the detection of infection in the latent phase of the disease. Nucleic acid-based assays are highly sensitive, free from immunocompetence and can differentiate between morphologically similar parasites. With the advent of newer diagnostics complemented with traditional ones will be of huge help for targeted selective treatment with better chemotherapeutic agents.

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.

Development of an immunochromatographic strip for the serodiagnosis of Theileria infection in sheep

Background

Theileria uilenbergi and T. luwenshuni are tick-borne protozoan parasites, transmitted by Haemaphysalis qinghaiensis and H. longicornis, respectively. They are the main causative agents of theileriosis in small ruminants in China. The disease has resulted in severe economic losses and hindered the development of sheep and goat husbandry industry in the endemic regions.

Methods

In this study, a colloidal gold-based immunochromatographic strip (ICS) was developed for the detection of T. uilenbergi and/or T. luwenshuni infections. A recombinant T. uilenbergi immunodominant protein (rTuIP) was used as antigen for the ICS. The nitrocellulose membrane was incubated with rTuIP on the test (T) line and anti-rTuIP antiserum on the control (C) line, respectively. The rTuIP conjugated to colloidal gold particles was used as the detection system for visualization of the lines. Then the sample pad, conjugate pad, nitrocellulose membrane and absorbent pad were assembled onto a backing plate in the appropriate order.

Results

The ICS was able to detect antibodies in the sera of animals experimentally infected with T. uilenbergi from 14 to 85 days. It also reacted with the serum from T. luwenshuni infected sheep. However, there was no cross-reactivity with sera from animals infected with Babesia motasi and Anaplasma ovis. Comparison of the ICS with the rTuIP antigen based indirect enzyme-linked immunosorbent assays (ELISA) using test field samples showed good correlations with 93.1 % (81/87) sensitivity and 100 % (40/40) specificity, respectively, with an almost perfect agreement (Kappa = 0.895, P < 0.01).

Conclusion

An immunochromatographic strip test based on a recombinant T. uilenbergi immunodominant protein (rTuIP) was developed. This is a rapid test (approximately 15 min to completion) for the detection of T. uilenbergi and/or T. luwenshuni infection that is easy to perform and; delivers results that are visible to the naked eye.

Emerging tick-borne infections in mainland China: an increasing public health threat

Since the beginning of the 1980s, 33 emerging tick-borne agents have been identified in mainland China, including eight species of spotted fever group rickettsiae, seven species in the family Anaplasmataceae, six genospecies in the complex Borrelia burgdorferi sensu lato, 11 species of Babesia, and the virus causing severe fever with thrombocytopenia syndrome. In this Review we have mapped the geographical distributions of human cases of infection. 15 of the 33 emerging tick-borne agents have been reported to cause human disease, and their clinical characteristics have been described. The non-specific clinical manifestations caused by tick-borne pathogens present a major diagnostic challenge and most physicians are unfamiliar with the many tick-borne diseases that present with non-specific symptoms in the early stages of the illness. Advances in and application of modern molecular techniques should help with identification of emerging tick-borne pathogens and improve laboratory diagnosis of human infections. We expect that more novel tick-borne infections in ticks and animals will be identified and additional emerging tick-borne diseases in human beings will be discovered.

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.

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.

Discrimination between ovine Babesia and Theileria species in China based on the ribosomal protein S8 (RPS8) gene

Ovine babesiosis and theileriosis are important hemoprotozoal diseases of sheep and goats in tropical and subtropical regions that lead to economic losses in these animals. PCR-restriction fragment length polymorphism (PCR-RFLP) is a reliable molecular diagnostic tool for discriminating Theileria or Babesia species in the same host. In this study, the DNA sequences of a ribosomal protein S8 (RPS8) gene from four species of piroplasms in China were used to develop a species-specific PCR-RFLP diagnostic tool. The sensitivity of the PCR assays was 0.1 pg DNA for B. motasi and 1 pg DNA for T. uilenbergi and 10 pg DNA for Babesia sp. Xinjiang-2005 and T. luwenshuni. The clear size difference of the PCR products allowed for a direct discrimination for B. motasi, Babesia sp. Xinjiang-2005 and ovine Theileria species (T. uilenbergi and T. luwenshuni), except that the mixed infection between T. uilenbergi and T. luwenshuni may be difficult to distinguish, simply after the electrophoretic separation of the amplification products. Further T. uilenbergi and T. luwenshuni diagnoses were made by digesting the PCR product with SacI. The established method could be applicable for the survey of parasite dynamics, and epidemiological studies as well as prevention and control of the disease.

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.

Babesia ovis as the main causative agent of sheep babesiosis in Iran

Babesiosis is a haemoparasitic disease with high economical losses in livestock industry worldwide. The early diagnosis and successful therapy of babesiosis belong to the key steps of control and health management of livestock. Ethanol-fixed blood samples of 400 sheep were analyzed for Babesia infection. Reverse line blot (RLB) was established specifically for Theileria lestoquardi, Theileria (China 1), Theileria (China 2), Theileria ovis, Theileria separata, Babesia ovis, Babesia motasi, Babesia crassa, and Babesia (Lintan). The DNA was extracted from the ethanol-fixed blood samples and amplified with a common primer pair derived from 18S rRNA gene, amplifying both Theileria spp. as well as Babesia spp. Regarding the differences in the length of nucleotide sequences of the polymerase chain reaction (PCR) products obtained from Theileria spp. and Babesia spp., the PCR products derived from Babesia spp. were out screened and analyzed by RLB. The RLB analysis showed that 28 samples within the 400 blood samples were B. ovis positive. No B. motasi, B. crassa, or Babesia (Lintan) could be detected. The sequence analysis of one PCR product as a representative for other B. ovis-positive PCR products confirmed the results of RLB. Our results and the results of other investigators showed that B. ovis could be considered as a main causative agent of sheep babesiosis in Iran. Furthermore, our results also showed that RLB can be used as a reliable method for a simultaneous differentiation of Theileria and Babesia species from each other.

Advances in diagnosis of protozoan diseases

Microscopy still remains the gold standard procedure for the diagnosis of many protozoan infections in animals, but the specific identification requires skilled and experienced personnel. Immunoassays, detecting antibodies or specific protozoan antigens, have been developed but often lack sensitivity and specificity due to close relationship between many protozoa. Recent research has focussed almost exclusively on molecular based techniques for the identification and quantification of parasite DNA in samples. Opinion differ on most appropriate targets to use and there are very few diagnostic kits available making comparison between laboratories difficult. Future research needs to focus on robust, cheap field diagnostic assays.

First molecular detection of Theileria ovis in Rhipicephalus sanguineus tick in Iran

OBJECTIVE

To determine tick infestation of domestic ruminants and their infection to ovine theileriosis in northern Iran.

METHODS

About 425 domestic ruminants in Ghaemshahr city in northern Iran were inspected for tick infestations. Twenty tick specimens (13 females and 7 males) of Rhipicephalus sanguineus (R. sanguineus), the most common tick in the study area, were tested by PCR amplification against 18s rRNA genome of Theileria spp using specie specific primers and then the PCR products were sequenced for species identification by comparison with data base available in GenBank.

RESULTS

About 323 ticks were collected from 102 animals (88 sheep, 12 goats and 2 cattle). The prevalence of ticks infesting animals was R. sanguineus (82.35%), Rhipicephalus bursa (R. bursa) (0.3%), Ixodes ricinus (I. ricinus) (15.2%), Boophilus annulatus (B. annulatus) (1.2%), Haemaphysalis punctata (H. punctata) (0.3%) and Haemaphysalis numidiana (H. numidiana) (0.6%). Eleven (55%) tick specimens were PCR positive against genome of Theileria ovis (T. ovis). Sequence analysis of the PCR products confirmed presence of T. ovis in one R. sanguinus.

CONCLUSIONS

This is the first report of tick infection to T. ovis in Iran. Due to dominant prevalence of R. sanguineus as well as its infection to T. ovis, it is postulated this tick is the main vector of ovine theileriosis in northern Iran.

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.

BQP35 is a novel member of the intrinsically unstructured protein (IUP) family which is a potential antigen for the sero-diagnosis of Babesia sp. BQ1 (Lintan) infection

A new gene of Babesia sp. BQ1 (Lintan) (BQP35) was cloned by screening a merozoite cDNA expression library with infected sheep serum and using rapid amplification of cDNA ends (RACE). The nucleotide sequence of the cDNA was 1140bp with an open reading frame (ORF) of 936bp encoding a 35-kDa predicted polypeptide with 311 amino acid residues. Comparison of BQP35 cDNA and genomic DNA sequences showed that BQP35 does not possess an intron. Recombinant BQP35 (rBQP35), expressed in a prokaryotic expression system, showed abnormally slow migration on SDS-PAGE. Gel shifting, amino acid sequence and in silico disorder region prediction indicated that BQP35 protein has characteristics of intrinsically unstructured proteins (IUPs). This is the first description of such proteins in the Babesia genus. BQP35 induced antibodies production as early as one week after Babesia sp. BQ1 (Lintan) infection in sheep. No cross-reaction was observed with sera from sheep infected with other ovine piroplasms dominant in China, except with Babesia sp. Tianzhu. The interest of BQP35 as a diagnostic antigen is discussed.

A highly sensitive DNA bead-based suspension array for the detection and species identification of bovine piroplasms

Piroplasms are among the most harmful tick-borne pathogens for livestock and sensitive and specific diagnostic methods for rapid detection and identification of the different species are needed for effective control. Reverse Line Blot has been the molecular technique of choice but it is laborious, time-consuming and highly susceptible to subjective variation in the interpretation of the hybridisation signal. Here, an oligonucleotide multiplex suspension microarray (Luminex® microsphere system) was developed for bovine piroplasms. Probes previously used in Reverse Line Blot for Babesia divergens, Babesia bovis, Babesia occultans, Babesia bigemina and Theileria buffeli, and a catch-all Theileria and Babesia control probe, were included in the Luminex assay together with newly designed probes for Theileria annulata and Babesia major. An internal amplification control that was detected with a Luminex probe was included to monitor for inhibition. Serially diluted linearised recombinant plasmids of the different species were used to assess the analytical sensitivity and specificity, and the detection limit of the Luminex assay was determined using serial dilutions of infected blood from an animal with a known level of T. annulata parasitaemia. The assay was then validated on 214 bovine blood samples analysed in parallel by Reverse Line Blot and Luminex. The Luminex assay proved to be highly specific and more sensitive than Reverse Line Blot, detecting 0.05 parasites/μl of blood. Technically, the Luminex procedure was rapid, provided high throughput screening, transformed the subjective interpretation of Reverse Line Blot results into numerical objective values, and allowed more flexibility in array preparation than Reverse Line Blot. The method described herein can substantially improve the detection of piroplasm carriers and thus better protect livestock trade and facilitate preventive control programs.

Detection and differentiation of Borrelia burgdorferi sensu lato in ticks collected from sheep and cattle in China

BACKGROUND

Lyme disease caused by Borrelia burgdorferi sensu lato complex is an important endemic zoonosis whose distribution is closely related to the main ixodid tick vectors. In China, isolated cases of Lyme disease infection of humans have been reported in 29 provinces. Ticks, especially ixodid ticks are abundant and a wide arrange of Borrelia natural reservoirs are present. In this study, we developed a reverse line blot (RLB) to identify Borrelia spp. in ticks collected from sheep and cattle in 7 Provinces covering the main extensive livestock regions in China.

RESULTS

Four species-specific RLB oligonucleotide probes were deduced from the spacer region between the 5S-23S rRNA gene, along with an oligonucleotide probe which was common to all. The species specific probes were shown to discriminate between four genomic groups of B. burgdorferi sensu lato i.e. B. burgdorferi sensu stricto, B. garinii, B. afzelii, and B. valaisiana, and to bind only to their respective target sequences, with no cross reaction to non target DNA. Furthermore, the RLB could detect between 0.1 pg and 1 pg of Borrelia DNA.A total of 723 tick samples (Haemaphysalis, Boophilus, Rhipicephalus and Dermacentor) from sheep and cattle were examined with RLB, and a subset of 667 corresponding samples were examined with PCR as a comparison. The overall infection rate detected with RLB was higher than that of the PCR test.The infection rate of B. burgdoreri sensu stricto was 40% in south areas; while the B. garinii infection rate was 40% in north areas. The highest detection rates of B. afzelii and B. valaisiana were 28% and 22%, respectively. Mixed infections were also found in 7% of the ticks analyzed, mainly in the North. The proportion of B. garinii genotype in ticks was overall highest at 34% in the whole investigation area.

CONCLUSION

In this study, the RLB assay was used to detect B. burgdorferi sensu lato in ticks collected from sheep and cattle in China. The results showed that B. burdorferi senso stricto and B. afzelii were mainly distributed in the South; while B. garinii and B. valaisiana were dominant in the North. Borrelia spirochaetes were detected in Rhipicephalus spp for the first time. It is suggested that the Rhipicephalus spps might play a role in transmitting Borrelia spirochaetes.

Identification of different Theileria species (Theileria lestoquardi, Theileria ovis, and Theileria annulata) in naturally infected sheep using nested PCR-RFLP

Ovine theileriosis is an important hemoprotozoal disease of sheep and goats in tropical and subtropical regions that leads to economic losses in these animals. A nested PCR-restriction fragment length polymorphism (RFLP) was carried out to identification Theileria species in sheep in some area in western half of Iran (Sari, Rasht, Urmia, Ilam, and Ahvaz). Two hundred and fifty blood samples were taken from sheep during tick activating season (summer of 2008). Microscopic examination revealed that 9.2% (23/250) sheep were infected by Theileria spp. piroplasms. Parasitemia ranged from 0.011% to 0.015%. In nested PCR assessment of DNA samples, 32.8% (82/250) sheep were positive. The negative samples were confirmed by amplifying of ovine beta-actin gene as an internal control. The differentiation of Theileria species was based on RFLP patterns using three restriction enzymes: HpaII, Rsa1, and Bsh 1285I. Out of 82 positive samples, 54.8% (45/82) and 40.2% (33/82) were positive for Theileria lestoquardi and Theileria ovis respectively. Mixed infection was detected in 4.8% (4/82) cases. Based on their PCR product digestion pattern with HpaII (1178, 900, 278, and 106 bp), it seemed to be mixture of Theileria annulata and T. lestoquardi. The presence of T. annulata was supported by sequence analysis. This is the first report of naturally infected sheep with T. annulata in Iran. Geographical distribution of Theileria species in sheep is shown according to the result of microscopy and nested PCR and RFLP data.