First Molecular Detection of Babesia gibsoni in Dogs from Wuhan, China

Molecular epidemiological investigation of piroplasms carried by pet cats and dogs in an animal hospital in Guiyang, China

Piroplasmosis is a zoonotic disease mainly caused by the Babesia and Theileria parasites. Piroplasmosis is often a subclinical infection in dogs and cats that is difficult to detect and is often suspected when clinical signs such as anemia are present. It has been reported to be prevalent in China. However, molecular evidence of the disease has not been reported in pet dogs and cats in Guiyang. In this study, we collected 307 anticoagulated blood samples from an animal hospital in the Wudang District of Guiyang during the period March 2021 to November 2021 and extracted DNA from the samples. The 18S rDNA gene was amplified using PCR, and the positive amplification product was sequenced. The sequences were then analyzed for homology and phylogeny. Of the 307 samples collected, 164 were feline and 143 were canine, with a total of 23 amplifying a target band of approximately 400 bp. The percentage of positives of piroplasms infection in pet cats was 4.27% (7/164), with the pathogens being T. uilenbergi (3) and T. luwenshuni (4). One Colpodella sp. and two undetermined species were also detected in the cat samples. The percentage of positives of piroplasms infection in pet dogs was 7.69% (11/143), with the pathogen being T. uilenbergi (11). One Colpodella sp. was also detected in the dog samples. The results confirmed that T. uilenbergi and T. luwenshuni are prevalent in pet cats and dogs in this area. In addition, the study found a rare zoonotic pathogen, Colpodella sp., in cats and dogs. Therefore, this study is expected to serve as a valuable reference for decision-making regarding animal health management and public health work.

Epidemiological and phylogenetic investigation of Babesia spp. in dogs of Hainan Province/Island, China

Babesiosis is a significant tick-borne disease, which is globally prevalent. Many previous research studies have discussed the presence of Babesia gibsoni, Babesia vogeli, and Babesia canis in dogs in China. In the present study, we have used distinct molecular approaches to detect the presence of Babesia spp. in dogs of Hainan Province/Island, China. A total of 1106 dog blood samples were collected from the Island, of which 61 dog samples were found to be positive for Babesia vogeli. The highest infection rate was 56.7% (17/30) detected from Tunchang, followed by 25.0% (3/12) from Baisha and 10.4% (5/48) from Wenchang. There was only one positive case of Babesia gibsoni, and the infection rate was found to be 0.1% (1/1106). The sequencing results showed that the subjected sample sequences were identical and resembled the Babesia vogeli and Babesia gibsoni sequences available in the database. The results derived from this study will be helpful for planning effective strategies for the treatment, control, and prevention of babesiosis in dogs of Hainan Province/Island.

Epidemiological survey of tick-borne pathogens in dogs in Anhui Province, China

Tick-borne diseases have continued to increase worldwide in both developing and many developed countries due to the widespread of different tick species and tick's adaptability to different climatic weather. In order to investigate the prevalence of the tick-borne pathogens, EDTA-anticoagulated whole blood samples were aseptically collected from 765 pet dogs in twenty veterinary clinics located in sixteen prefecture-level cities in Anhui Province, China, and the samples were examined and analyzed for tick-borne pathogens using both microscopy and PCR. Our result analysis revealed 17(2.22%) positive samples to Babesia spp and 4(0.52%) positive samples to Hepatozoon spp, of which case of co-infection was recorded in Lu'An and Chuzhou. The BLAST analysis results of the 18S rRNA gene revealed that the dogs were infected with Babesia gibsoni and Hepatozoon canis. All samples were negative for Anaplasma spp., Ehrlichia spp., and Rickettsia spp. This is the first molecular report of B. gibsoni and H. canis in dogs in Anhui, China.

Human pathogens in ticks removed from humans in Hebei, China

Ticks are the hosts or vectors of many human pathogens, including viruses, bacteria and protozoa, and can transmit these causative agents to humans when feeding on human bodies. In this study, 26 ticks removed from humans in Hebei, China were tested for the presence of human-pathogenic microorganisms by Polymerase Chain Reaction (PCR) or Reversed Transcript PCR (RT-PCR). As a result, 11 ticks tested positive for at least one human pathogen. Specifically, four validated human pathogens, including Rickettsia raoultii, Candidatus Rickettsia tarasevichiae, Babesia venatorum, and Borrelia garinii, as well as Anaplasma ovis with zoonotic potential, were identified in Ixodes persulcatus, Dermacentor silvarum and Haemaphysalis concinna. Importantly, this is the first report of Anaplasma and Babesia species pathogenic to humans in Hebei province. Moreover, the co-infections, including double infection and quadruple infection were observed. In addition, Candidatus R. principis with unknown pathogenicity was identified in one tick, which may be the same species as Candidatus R. hongyuanensis based on the nucleotide identity and phylogenetic analysis. Concluding, four validated tick-borne pathogens and one with zoonotic potential were identified in ticks parasitizing humans, suggesting the potential high public health risk in the local human population.

Analysis of genetic diversity and population structure of Babesia gibsoni

Babesia gibsoni is a tick-borne apicomplexan protozoan causing canine babesiosis. This parasite has diploid sexual reproduction in ticks, during which genetic exchanges can occur leading to increased genetic diversity, which is an important factor in adapting to environmental changes. Exploring the genetic variation of B. gibsoni population can provide a foundation for understanding the patterns of disease transmission and developing babesiosis control strategies. Partial 18S rRNA fragment sequences were obtained from 11 B. gibsoni isolates collected from different regions in China and 117 publicly available sequences were from 12 geographical areas including China. The genetic variation, demographic expansion and population structure were examined. A total of 34 haplotypes were identified among B. gibsoni populations. Analysis of molecular variance, pairwise Fst and structure analysis showed that high genetic variation within populations, low genetic differentiation and obvious mixture haplotype were apparent in a single continent, but higher genetic differentiation was detected across different continents. Neutrality tests implied that B. gibsoni populations had experienced population extension. These findings will contribute to understand the genetics and evolution of B. gibsoni and will be useful for formulating effective management strategies to prevent and control this parasite.

18S rRNA Gene-Based Piroplasmid PCR: An Assay for Rapid and Precise Molecular Screening of Theileria and Babesia Species in Animals

PURPOSE

The parasites of genera such as Babesia and Theileria are called piroplasmids due to the pear-shaped morphology of the multiplying parasite stages in the blood of the vertebrate host. Because of the enormous number of parasite species and the challenges of multiplex PCR, initial screening of samples using piroplasmid-specific PCR may be a more cost-effective and efficient technique to identify parasite species, especially during epidemiological studies. Accordingly, 18S rRNA PCR was standardized and optimized on common piroplasmids of different animals like cattle, buffaloes, sheep, goats, dogs, horses, and leopards.

METHODS

Bloods samples from 1250 animals were collected from different animals in Junagadh district of Gujarat, India. 18S rRNA PCR was standardized and optimized as a primary method for molecular screening of piroplasms in domestic and wild animals. The method was checked for its analytical sensitivity and specificity. Parasite species-specific PCR and sequencing was used to validate the test. Moreover, in-silico restriction enzyme (RE) analysis was also done to assess its applicability in PCR-RFLP.

RESULTS

Piroplasm infections were recorded in 63.3% of animals in Junagadh. The 18S rRNA PCR detected the piroplasmid DNA in as low as 39 picograms (pg) of whole blood genomic DNA isolated from microscopically Theileria positive blood samples and no reactivity was recorded from common but unrelated haemoparasites viz., Trypanosoma evansi, Hepatozoon spp., Anaplasma spp., and Ehrlichia canis was observed. The 18S rRNA PCR assay findings were confirmed by species-specific PCR and sequencing. Analysis of different sequences generated using 18S rRNA PCR revealed that the amplicon size of Babesia spp. is nearly 400 bp (393-408 bp) whereas Theileria spp. were more than 400 bp (418-424 bp). The percentage of sequence divergence among Babesia and Theileria spp. was 7.3-12.2% and 0.7-12.2%, respectively. In-silico restriction enzyme (RE) analysis reveals the presence of at least one site for a commercially available RE in 18S rRNA fragments of every parasite, which can differentiate it from its congeners.

CONCLUSIONS

The presented universal oligonucleotide-based PCR assay provides a highly sensitive, specific, cost-effective, and rapid diagnostic tool for the initial screening of piroplasmids infecting domestic and wild animals and is potentially helpful for large-scale epidemiological studies.

First Report of Babesia gibsoni in Cats in China

As there are few studies of Babesia spp. infection in cats in China, or anywhere in the world, the aim of this study was to explore the epidemic features of babesiosis in pet cats in China. In total, 429 blood samples were randomly collected in four different geographical regions. The 18S rRNA gene fragment of Babesia spp. was amplified by nest polymerase chain reaction (PCR), and haplotype and phylogenetic analysis of Babesia were performed to analyze the relationship of this protozoa. The total positive rate of infection was 2.8%. BLAST analysis indicated that Babesia gibsoni was detected in 12 cats. Among these, 4.3%, 3.1%, 0.8% and 2.0% were from Chongqing, Fujian, Hubei and Shandong, respectively. Haplotype and phylogenetic analysis showed that there were nine haplotypes and no obvious genetic variation among B. gibsoni populations. This is the first report of B. gibsoni in cats in China. These findings will be helpful for understanding the epidemiology of Babesia spp. in China, and provide a foundation for developing effective preventative strategies.

A novel promising diagnostic candidate selected by screening the transcriptome of Babesia gibsoni (Wuhan isolate) asexual stages in infected beagles

BACKGROUND

Babesia gibsoni is one of the causative agents of canine babesiosis worldwide. Some dogs infected with B. gibsoni show severe clinical signs with progressive anemia, hemoglobinuria and splenomegaly. However, most infected dogs present a state of chronic infection and thereby may be a persistent pathogen carrier, increasing the risk of pathogen spreading. To date, little is known about this pathogen, with genomic and transcriptomic data in particular generally unavailable. This lack of knowledge extensively limits the development of effective diagnostic strategies and vaccines.

METHODS

High-throughput RNA sequencing of total RNA of B. gibsoni asexual stages collected from infected beagles was performed. The unigenes were annotated in seven databases. The genes were sorted according to their fragments per kilobase per million (FPKM) value, which was used as an indicator for expression level. The gene with the highest FPKM value was cloned from the genome of B. gibsoni and further tested for immunogenicity, cellular localization and efficacy as a potential diagnostic candidate for detecting B. gibsoni in sera collected from beagles.

RESULTS

A total of 62,580,653 clean reads were screened from the 64,336,475 raw reads, and the corresponding 70,134 transcripts and 36,587 unigenes were obtained. The gene with the highest FPKM value was screened from the unigenes; its full length was 1276 bp, and it was named BgP30. The BgP30 gene comprised three exons and two introns, with a 786-bp open reading frame, and encoded 261 amino acids with a predicted molecular weight of 30 kDa. The cellular localization assay confirmed the existence of P30 protein in B. gibsoni parasites. Moreover, P30 was detected in the serum of experimentally B. gibsoni-infected beagles, from 15 days up to 422 days post-infection, suggesting its usefulness as a diagnostic candidate for both acute and chronic infections.

CONCLUSIONS

We sequenced the transcriptome of B. gibsoni asexual stages for the first time. The BgP30 gene was highly expressed in the transcriptome screening experiments, with further studies demonstrating that it could induce immune response in B. gibsoni-infected dogs. These results lead us to suggest that bgP30 may be a good diagnostic candidate marker to detect both acute and chronic B. gibsoni infections.

18S rRNA Gene-Based Piroplasmid PCR: An Assay for Rapid and Precise Molecular Screening of Theileria and Babesia Species in Animals

Purpose

The parasites of genera such as Babesia and Theileria are called piroplasmids due to the pear-shaped morphology of the multiplying parasite stages in the blood of the vertebrate host. Because of the enormous number of parasite species and the challenges of multiplex PCR, initial screening of samples using piroplasmid-specific PCR may be a more cost-effective and efficient technique to identify parasite species, especially during epidemiological studies. Accordingly, 18S rRNA PCR was standardized and optimized on common piroplasmids of different animals like cattle, buffaloes, sheep, goats, dogs, horses, and leopards.

Methods

Bloods samples from 1250 animals were collected from different animals in Junagadh district of Gujarat, India. 18S rRNA PCR was standardized and optimized as a primary method for molecular screening of piroplasms in domestic and wild animals. The method was checked for its analytical sensitivity and specificity. Parasite species-specific PCR and sequencing was used to validate the test. Moreover, in-silico restriction enzyme (RE) analysis was also done to assess its applicability in PCR–RFLP.

Results

Piroplasm infections were recorded in 63.3% of animals in Junagadh. The 18S rRNA PCR detected the piroplasmid DNA in as low as 39 picograms (pg) of whole blood genomic DNA isolated from microscopically Theileria positive blood samples and no reactivity was recorded from common but unrelated haemoparasites viz., Trypanosoma evansi, Hepatozoon spp., Anaplasma spp., and Ehrlichia canis was observed. The 18S rRNA PCR assay findings were confirmed by species-specific PCR and sequencing. Analysis of different sequences generated using 18S rRNA PCR revealed that the amplicon size of Babesia spp. is nearly 400 bp (393–408 bp) whereas Theileria spp. were more than 400 bp (418–424 bp). The percentage of sequence divergence among Babesia and Theileria spp. was 7.3–12.2% and 0.7–12.2%, respectively. In-silico restriction enzyme (RE) analysis reveals the presence of at least one site for a commercially available RE in 18S rRNA fragments of every parasite, which can differentiate it from its congeners.

Conclusions

The presented universal oligonucleotide-based PCR assay provides a highly sensitive, specific, cost-effective, and rapid diagnostic tool for the initial screening of piroplasmids infecting domestic and wild animals and is potentially helpful for large-scale epidemiological studies.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11686-022-00625-2.

Van İlindeki Sokak Köpeklerinde Babesia Türlerinin Polimeraz Zincir Reaksiyonu Yöntemi İle Araştırılması

Amaç: Köpek babesiosisi Babesia spp.’ nin neden olduğu hemolitik anemi, splenomegali, trombositopeni ve ateşe neden olabilen kene kaynaklı bir protozoal hastalıktır. Türkiye’de yapılan moleküler çalışmalar soncunda B. canis, B. gibsoni, B. vogeli, B. rossi ve B. vulpes türlerinin varlığı ortaya konulmuştur. Yapılan literatür taramalarına göre Van ilinde yaşayan köpeklerde Babesia türlerini ortaya koyan herhangi bir çalışma bulunmamaktadır. Bu çalışma, Van ilindeki köpeklerde babesiosisin varlığı ve yaygınlığının Polimeraz Zincir Reaksiyonu (PZR) tekniği ile araştırılması amacıyla yapılmıştır. Yöntem: Rastgele seçilen toplam 100 asemptomatik köpeğin vena cephalica antebrachii’lerinden EDTA’lı tüplere kan örnekleri alınmıştır. Alınan örneklerden elde edilen DNA’lar, Babesia spp.’ nin varlığı yönünden 18S ribozomal RNA geninin amplifiye edildiği PZR yöntemi ile araştırılmıştır. Bulgular: Muayene edilen 100 köpeğin PZR sonuçlarına göre hiçbirinde Babesia spp. DNA’sına rastlanmamıştır. Sonuç: Bu çalışma ile Van yöresi sokak köpeklerinde ilk kez Babesia spp. türleri moleküler olarak araştırılmıştır.

Establishment and Application of an Indirect Enzyme-Linked Immunosorbent Assay for Measuring GPI-Anchored Protein 52 (P52) Antibodies in Babesia gibsoni-Infected Dogs

Babesia gibsoni is a malaria-like protozoan that parasitizes the red blood cells of canids to cause babesiosis. Due to its high expression and essential function in the survival of parasites, the Glycosylphosphatidylinositol (GPI) anchor protein family is considered an excellent immunodiagnostic marker. Herein, we identified a novel GPI-anchored protein named as BgGPI52-WH with a size of 52 kDa; the recombinant BgGPI52-WH with high antigenicity and immunogenicity was used as a diagnostic antigen to establish a new iELISA method. The iELISA had a sensitivity of 1:400, and no cross-reaction with other apicomplexan parasites occurred. We further demonstrated that the degree of variation was less than 10% using the same samples from the same or different batches of an enzyme-labeled strip. It was found that the method was able to detect early infection (6 days after infection) in the sera of the B. gibsoni-infected experimental dogs in which antibody response to rBgGPI52-WH was evaluated. Clinical sera from pet hospitals were further tested, and the average positive rate was about 11.41% (17/149). The results indicate that BgGPI52-WH is a reliable diagnostic antigen, and the new iELISA could be used as a practical method for the early diagnosis of B. gibsoni.

First detection and molecular identification of Babesia gibsoni and Hepatozoon canis in an Asiatic wild dog (Cuon alpinus) from Thailand

Babesia spp. and Hepatozoon spp. are apicomplexan parasites that infect a wide range of domestic and wild animals. The life cycle of these parasites requires a tick vector as a definitive host and various vertebrates as reservoir hosts. The objective of this study was to detect and characterize Babesia spp. and Hepatozoon spp. in an Asiatic wild dog (Cuon alpinus) from a natural habitat in northeastern Thailand. Heart and spleen samples of an adult male wild dog were screened for Babesia spp. and Hepatozoon spp. by polymerase chain reaction (PCR) of the partial fragment of 18S ribosomal RNA gene sequence. Both Babesia sp. and Hepatozoon sp. were detected in the spleen of the wild dog. Nucleotide sequence and phylogenetic analyses showed that the detected parasites were Babesia gibsoni and Hepatozoon canis. This is the first report of B. gibsoni and H. canis in the Asiatic wild dog from Thailand using PCR. Our results indicate that wild dogs can serve as a potential reservoir of the protozoan parasites and that they may play an important role in the transmission of these parasites to other wild or domestic canids.

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The Asiatic wild dog (Cuon alpinus) is involved in the cycle of tick-borne pathogens (TBP).

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This is the first report of Babesia gibsoni and Hepatozoon canis co-infection in an Asiatic wild dog.

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Wild dogs may be a source of TBP for other wild and domestic canids.

THE INFECTION AND SPECIES IDENTIFICATION OF CANINE BABESIA SPP. IN PARTS OF SHAANXI PROVINCE

Canine babesiosis is a serious disease among tick-borne haemoprotozoan diseases that threaten dog health. To find out the prevalence of canine babesiosis and its main pathogenic species in Shaanxi Province, the study was centered on the infection of babesiosis in dogs in different regions of the Province. First, a total of 367 blood samples were collected in Shaanxi Province, and 53 Babesia nucleic-acid-positive samples were found by polymerase chain reaction (PCR) identification, with a positive rate of 14.44%, and Babesia gibsoni was found by sequencing analysis. Further analysis showed that the prevalence of canine babesiosis was significantly different in 5 regions. There was no significant difference in infection rates between age groups, with the lowest prevalence in young dogs (10.81%) and the highest in adult dogs (17.29%). The infection rate in male dogs was higher than in female dogs. The morbidity of canine Babesia spp. was significantly different between different seasons, with the highest infection rate in autumn (27.78%) and the lowest in winter (6.10%). In conclusion, the epidemicity of canine Babesia spp. in dogs was mainly affected by region and season, and B. gibsoni was the most common canine Babesia spp. within Shaanxi Province in our study. These results provide basic data for the prevention and control of canine babesiosis in this region.

PCR detection and genetic characterization of piroplasms from dogs in Myanmar, and a possible role of dogs as reservoirs for Theileria parasites infecting cattle, water buffaloes, and goats

Canine vector-borne pathogens can act as zoonotic agents in humans; however, it poorly understood whether dogs play a role as reservoirs of vector-borne parasites in livestock animals. Here, we report the unexpected detection of 18S rRNA gene (rDNA) sequences of five ruminant Theileria species from the peripheral blood of dogs in Myanmar, in addition to those of two canine Babesia species. Using novel BTH primers capable of amplifying the 18S rDNA of Babesia, Theileria, and Hepatozoon spp., approximately 1,500 bp nested PCR products were detected in 19% (17/91) of local or imported dog breeds in different regions of Myanmar. Among the sequences of the 17 PCR products, ten were determined as Theileria 18S rDNA, including three as Theileria orientalis, three as Theileria buffeli, two as Theileria cf. velifera, one as Theileria luwenshuni, and one as Theileria sp. Most of these sequences showed higher identities with Theileria sequences determined in previous studies of cattle, water buffaloes, and goats in Myanmar. Six PCR products were identified as Babesia vogeli and one sample was determined as Babesia gibsoni. Furthermore, we obtained approximately 900 bp thrombospondin-related adhesive protein (TRAP) gene fragments from three dog blood DNA samples. Phylogenetic analysis of the TRAP gene showed that B. gibsoni parasites in Myanmar were considerably related to isolates from China, Korea, Japan, and Taiwan, but clearly separated from those from Bangladesh and India. These results provide new insights into a possible role of dogs in maintaining and spreading tick-borne pathogens among livestock and canine populations in Myanmar.

Survey and Molecular Study of Babesia gibsoni in Dogs of Baghdad Province, Iraq

This study aimed to detect Babesia gibsoni (B. gibsoni) in dogs of different ages, sex and breeds in Baghdad province by microscopic and molecular investigations using polymerase chain reaction (PCR), sequencing, and phylogenetic analyses. The present study was investigated B. gibsoni in 310 blood samples of dogs for the period from December 2018 to September 2019 in Baghdad province, Iraq. The molecular study was carried out by using universal primers of Babesia spp. (PIRO-A and PIRO-B) and specific primers of B. gibsoni (BAGIF and BAGIR) products size of 410 bp and 488 bp fragments of 18S rRNA gene respectively. The clinical signs revealed higher percentage and specific clinical signs of B. gibsoni as depression, anorexia, fever, pale mucus membrane, and ticks infestation, however icterus, and dead were low in which only occurred in two dogs out of infected dogs. The PCR assay and microscopic diagnosis revealed the infection rate of B. gibsoni 9 out of 310 (2.9%) in dogs. The sequence data analyses of nine DNA products were 98-100% similar to sequences of 18S rRNA gene of B. gibsoni data available in Gene bank. According to breed, age, and sex, the results revealed a significantly high-risk factor of infection in Husky dogs; B. gibsoni detected in females which was increased non-significantly than males; while the highest occurrence of disease was in young dogs aged three years or less in addition to the above, the infection rate of B. gibsoni was high in spring season. In conclusion, this study was considered the first molecular record of B. gibsoni in Baghdad, Iraq documented no differences in diagnosis by blood smear and conventional PCR to amplify of 18S rRNA gene and partial sequencing of B. gibsoni with low-cost method and easily done.

Molecular evidence of piroplasm infection in companion animals in Hunan Province, China

BACKGROUND

Feline and canine babesiosis is an important tick-borne disease caused by parasites of the genus Babesia. The disease has a worldwide distribution and causes serious health problems in domestic and wild canidae and felidae.

RESULTS

Genomic DNA was isolated from blood samples, which were randomly collected from pet dogs (n = 115) and cats (n = 25) in Changsha city of Hunan Province, China. Results of nested PCR assay targeting 18S rRNA gene and partial gene sequencing revealed that seven animals were infected with Babesia species, five dogs (5/115, 4.3%) and two cats (2/25, 8.0%). Sequence analysis showed that four dogs (3.5%) were positive for Babesia canis, and the other one for Babesia vogeli (0.87%). The two cats were infected by Babesia hongkongensis.

CONCLUSIONS

The findings of this study will expand knowledge of the distribution of Babesia species and provide important epidemiological information for the control of animal babesiosis in China.

Molecular detection and genetic characteristics of Babesia gibsoni in dogs in Shaanxi Province, China

Background

Several members of genus Babesia are important pathogens causing babesiosis in dogs. In China, at least five Babesia species have been described in dogs or ticks. This study sought to determine the prevalence and molecular characteristics of various Babesia spp. in dogs in cities in Shaanxi Province in China, including Xi’an and Hanzhong.

Methods

A total of 371 blood samples were collected from pet dogs presenting to veterinary clinics in the cities of Xi’an and Hanzhong in Shaanxi, China. Babesia spp. DNA was detected via amplification of partial 18S rRNA genes by semi-nested PCR. Almost full-length 18S rRNA, ITS, partial TRAP and complete cytb genes were recovered for analysis of the genetic characteristics and relationships with known isolates.

Results

A single species, Babesia gibsoni, was identified in dogs in Xi’an and Hanzhong. Consistently, B. gibsoni was also detected in 14 ticks collected from positive dogs. Sequence similarities and phylogenetic analysis suggested that the isolates identified herein showed a closer genetic relationship with isolates from East Asian countries rather than India, Bangladesh, or the USA. Sequence analysis based on tandem repeat analysis of the TRAP gene further revealed that specific haplotypes were circulating in both Xi’an and Hanzhong, with no specific regionality. In addition, 10.9% of all isolates with atovaquone (ATV)-resistance were identified because of M121I mutation in the deduced cytb protein.

Conclusions

This study revealed a high prevalence rate of Babesia infection. Babesia gibsoni was the only Babesia species identified in cases of canine babesiosis in the cities of Xi’an and Hanzhong cities in Shaanxi, China. In addition, the TRAP gene presented high genetic diversity across isolates. Such information is useful for elucidating the epidemiological characteristics of canine babesiosis, as well as the overall genetic diversity of Babesia spp. circulating in dog populations in Shaanxi Province.

Prevalence and molecular characterization of Babesia in pet dogs in Shenzhen, China

Canine babesiosis is an important global tick-borne infectious disease of domestic dogs and wild canids. B. gibsoni and B. vogeli are the most widespread species mainly endemic in dog population in southern and eastern regions of China. In this study, 272 blood samples were collected from pet dogs in five districts of Shenzhen, China. Babesia DNA was detected in 30 samples with an overall prevalence of 11.0 % in pet dogs in Shenzhen. The difference in the positive rate between female and male pet dogs, among different breed, and among the five sampling sites was not significant, while the age and health status of pet dogs significantly influence the positive rate of Babesia spp. infection. Sequencing results showed the presence of only B. vogeli in all of the samples tested. Sequence comparison and phylogenetic analysis revealed that all 30 strains of Babesia identified in this study shared the highest identity with B. vogeli. In sum, all results of this study showed a considerable high infection rate of Babesia spp. in pet dogs, and B. vogeli was the only Babesia species infecting pet dogs in Shenzhen city. Such information is necessary to help to elucidate the epidemiology of canine babesiosis in Shenzhen, and it is necessary to actively monitor this disease in pet dogs.

Molecular evidence of Babesia in pet cats in mainland China

BACKGROUND

Babesia spp. are important emerging tick-borne protozoan hemoparasites, and pose a great impact on companion animals. Canine babesiosis has been well described worldwide, while felis babesiosis has primarily been reported from South Africa. To the best of our knowledge, Babesia spp. infections in dogs have been well elucidated in pet dog population in China, no report about Babesia spp. infection in cat population in mainland China.

RESULTS

In this study, a total of 203 blood samples were collected from pet cats in Shenzhen city, and detected the presence of Babesia spp. with nested-PCR. Sequence comparison based on the 18S rRNA gene and ITS region revealed that three cats (1.48%) were infected with Babesia. vogeli. Notably, the sequences of ITS region obtained in this study shared the highest nucleotide identity with the sequence of B. vogeli strain isolated in cat from Taiwan.

CONCLUSIONS

This study is the first report about babesiosis in domestic cats, and also provides molecular evidence of Babesia spp. infection in cat in mainland China. The data present in this study suggest B. vogeli may be circulating in cat population in mainland China. Further study to investigate the epidemiology of Babesia infection in cat nationwide is warranted.

Evaluation of Babesia gibsoni GPI-anchored Protein 47 (BgGPI47-WH) as a Potential Diagnostic Antigen by Enzyme-Linked Immunosorbent Assay

Babesia gibsoni is one of the important pathogens causing severe incurable canine babesiosis, suggesting the necessity to develop a sensitive, specific, and highly automated diagnostic method for clinical application. Surface proteins are ideal candidates for diagnostic targets because they are the primary targets for host immune responses during host-parasite interactions. Glycosylphosphatidylinositol (GPI)-anchored proteins are abundant on the surface of parasites and play an important role in parasite diagnosis. In this study, a GPI-anchored protein named BgGPI47-WH was obtained and mouse anti-rBgGPI47-WH polyclonal antibody was produced by immunizing mice with the purified protein and Freund's adjuvant. Western blot was used to identify the native form and immunogenicity of BgGPI47-WH. An ELISA method was established by using recombinant BgGPI47-WH protein to evaluate its potential as a diagnostic antigen and the established method exhibited high specificity. The antibody response was evaluated by using the B. gibsoni-infected sera collected from different experimental dogs and the established ELISA could recognize antibodies at day 6 until day 101 post infection, indicating the potential use of BgGPI47-WH for early stage diagnosis. The specificity of the established ELISA was further evaluated by using 147 clinical samples collected from animal hospitals and 17.0% (25/147) of the samples were tested positive, with an overall proportion agreement of 86.39% between the results from BgGPI47-WH and BgSA1. Our results indicated that BgGPI47-WH could be used as a reliable diagnostic antigen and this study has proposed a practical method for early diagnosis of B. gibsoni.

Molecular detection and genetic diversity of Babesia canis canis in pet dogs in Henan Province, China

Canine babesiosis is an important tick-borne disease caused by Babesia spp. A total of 130 blood samples were randomly collected from pet dogs in Zhengzhou city, Henan Province, China, and screened for the presence of piroplasms with nested PCR and gene sequencing targeting the 18S rRNA gene. On the basis of blast analysis of the 18S rRNA gene sequences, our results revealed that seven dogs (5.4%) were infected with Babesia canis canis. The sequences were compared with those in GenBank, and alignments showed that all B. canis canis isolates belonged to genotype B. This is the first report of B. canis canis infection in dogs in China.

Babesia gibsoni endemic to Wuhan, China: mitochondrial genome sequencing, annotation, and comparison with apicomplexan parasites

Babesia gibsoni (B. gibsoni), an intracellular apicomplexan protozoan, poses great threat to canine health. Currently, little information is available about the B. gibsoni (WH58) endemic to Wuhan, China. Here, the mitochondrial (mt) genome of B. gibsoni (WH58) was amplified by five pairs of primers and sequenced and annotated by alignment with the reported mt genome sequences of Babesia canis (B. canis, KC207822), Babesia orientalis (KF218819), Babesia bovis (AB499088), and Theileria equi (AB499091). The evolutionary relationships were analyzed with the amino acid sequences of cytochrome c oxidase I (cox1) and cytochrome b (cob) genes in apicomplexan parasite species. Additionally, the mt genomes of Babesia, Theileria, and Plasmodium spp. were compared in size, host infection, form, distribution, and direction of the protein-coding genes. The full size of the mt genome of B. gibsoni (WH58) was 5865 bp with a linear form, containing terminal-inverted repeats on both ends, six large subunit ribosomal RNA fragments, and three protein-coding genes: cox1, cob, and cytochrome c oxidase III (cox3). Babesia, Theileria, and Plasmodium spp. had a similar mt genome size of about 6000 bp. The mt genomes of parasites that cause canine babesiosis showed a slightly smaller size than the other species. Moreover, Babesia microti (R1 strain) was about 11,100 bp in size, which was twice larger than that of the other species. The mt form was linear for Babesia and Theileria spp. but circular for Plasmodium falciparum and Plasmodium knowlesi. Additionally, all the species contained the three protein-coding genes of cox1, cox3, and cob except Toxoplasma gondii (RH strain) which only contained the cox1 and cob genes. The phylogenetic analysis indicated that B. gibsoni (WH58) was more identical to B. gibsoni (AB499087), B. canis (KC207822), and Babesia rossi (KC207823) and most divergent from Babesia conradae in Babesia spp. Despite the highest similarity to B. gibsoni (AB499087) reported in Japan, B. gibsoni (WH58) showed notable differences in the sequence of nucleotides and amino acids and the property in virulence to host and in vitro cultivation. This study compared the mt genomes of the two B. gibsoni isolates and other parasites in the phylum Apicomplexa and provided new insights into their differences and evolutionary relationships.

Detection of Babesia gibsoni in dogs by combining recombinase polymerase amplification (RPA) with lateral flow (LF) dipstick

Babesia gibsoni is a protozoan parasite responsible for the majority of reported cases of canine babesiosis in China. Currently, microscopic examination of the Giemsa-stained thin blood smears is the main diagnosis method in clinic. Here, we report the recombinase polymerase amplification-lateral flow (LF-RPA) dipstick detection method for targeting B. gibsoni cytochrome c oxidase subunit I (cox I) gene. The reaction takes only 20-30 min under isothermal temperatures between 30 and 45 °C. Specificity was evaluated using DNA from related apicomplexan parasites and their host, while the sensitivity was calculated based on the DNA from the experimental B. gibsoni-infected dogs. Results indicated that the LF-RPA method is 20 times more sensitive than the conventional PCR based on 18S rRNA and has no cross reaction with any other test DNAs. The applicability of the LF-RPA method was further evaluated using 15 samples collected from clinic. Thirteen of the 15 samples (86.67%) were detected as positive by LF-RPA, while 10 of them (66.67%) were found positive by conventional PCR. Overall, the novel LF-RPA assay is effective for the detection of B. gobsini and has considerable advantages over the conventional PCR in sensitivity, specificity, simplicity in operation, less time consumption, and visual detection. The LF-RPA method may facilitate the surveillance and early detection of B. gibsoni infection in dogs.

Molecular evidence for the transovarial passage of Babesia gibsoni in Haemaphysalis hystricis (Acari: Ixodidae) ticks from Taiwan: a novel vector for canine babesiosis

BACKGROUND

Babesia gibsoni is the predominant tick-borne protozoan blood parasite affecting dogs throughout the Oriental region. Babesia gibsoni is transmitted by Haemaphysalis longicornis, whereas a similar role has been suggested for Rhipicephalus sanguineus. Haemaphysalis longicornis does not occur in Taiwan, but R. sanguineus is widely distributed on dogs. However, clinical cases of babesiosis are mainly restricted to the northern part of the island. The discrepancy between tick distribution and clinical cases stimulated us to investigate the tick species distribution on dogs in northern Taiwan, with the aim to identify the local vector for canine babesiosis.

METHODS

Ticks were collected from stray dogs or free ranging pet dogs in northern Taiwan between 2015 and 2017 and, after identification, were tested for the presence of tick-borne Babesia parasites using PCR and reverse line blot (RLB) hybridisation. Moreover, engorged ticks collected from the dogs were incubated at 28 °C to allow them to oviposit. Their subsequent larval progeny was also examined by PCR/RLB.

RESULTS

A total of 1085 ticks collected from 144 stray dogs at different residential areas consisted of 5 different species: H. hystricis (n = 435), R. sanguineus (n = 582), R. haemaphysaloides (n = 43), Amblyomma testudinarium (n = 14) and Ixodes ovatus (n = 11) were identified. Babesia gibsoni DNA was detected in H. hystricis females (10.3%), males (7.0%) and in 2.6% of the nymphs. One R. sanguineus female and one A. testudinarium female tick also carried B. gibsoni DNA. DNA of B. gibsoni was demonstrated in 11 out of 68 (16.2%) batches of larval ticks derived from engorged H. hystricus ticks only. Babesia vogeli DNA was detected only in R. sanguineus females (2.6%) and males (2.4%). DNA of B. vogeli was detected in 13 out of 95 (13.7%) batches of larval ticks derived from engorged R.sanguineus females.

CONCLUSIONS

Babesia gibsoni DNA was detected in the larval progeny of H. hystricis ticks only, whereas B. vogeli was restricted to the larvae of R. sanguineus. This provides evidence for transovarial passage of B. gibsoni in H. hystricis and evidence that this tick does act as the local vector for this parasite on dogs in northern Taiwan where most cases of babesiosis are reported. The vectorial capacity of R. sanguineus for babesiosis is probably restricted to the transmission of B. vogeli only.