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Alkathiri B, Ahn K, Lee H, Cho YS, Youn SY, Seo MG, Kwak D, Shin S, Lee SH. Molecular epidemiology of Theileria species in ticks and its potential threat to livestock in the Republic of Korea. Acta Trop 2023; 238:106780. [PMID: 36471538 DOI: 10.1016/j.actatropica.2022.106780] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2022] [Revised: 11/24/2022] [Accepted: 11/25/2022] [Indexed: 11/29/2022]
Abstract
The purpose of this study was to investigate molecular epidemiology of Theileria spp. in ticks in Korea and assess their potential threat from wildlife animals to domestic animals. A total of 21152 hard ticks were collected from Chungcheong and Jeolla provinces of Korea from March to October 2021. Tick species were identified by microscopy and Theileria spp. were screened by nested PCR targeting 18S rRNA. Haemaphysalis spp. were the most abundant tick species, followed by H. longicornis, H. flava, Amblyomma testudinarium, and Ixodes nipponensis. Of the collected ticks, 6914 ticks (541 pools) were screened, and PCR showed 211 positive pools (39.0%; MIR: 3.05). The PCR and phylogenetic analysis identified two Theileria species, T. luwenshuni and Theileria sp., with T. luwenshuni (162/211, 76.78%; MIR: 2.34) being more abundant than Theileria sp. (36/211, 17.06%; MIR: 0.52); co-infection of the two species were noted (13/211, 6.16%; MIR: 0.19). Among the tick species, H. longicornis, especially nymphs, showed the highest prevalence. Regarding season, the highest prevalence was observed in May. Considering the tick and Theileria species identified in this study, H. longicornis nymph and cervine play a critical role in maintaining Theileria spp. in Korea and could be a potential threat to domestic animals, including deer and goats. In addition, there are significant correlations among tick distribution, region, season, and prevalence of Theileria.
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Affiliation(s)
- Badriah Alkathiri
- College of Veterinary Medicine, Chungbuk National University, Chungbuk 28644, Republic of Korea
| | - KyuSung Ahn
- College of Veterinary Medicine, Chonnam National University, Gwangju 61186, Republic of Korea
| | - Haeseung Lee
- College of Veterinary Medicine, Kyungpook National University, Daegu 41566, Republic of Korea
| | - Yun Sang Cho
- Parasitic and Honeybee Disease Laboratory, Bacterial and Parasitic Disease Division, Department of Animal & Plant Health Research, Animal and Plant Quarantine Agency, Gimcheon 39660, Republic of Korea
| | - So Youn Youn
- Parasitic and Honeybee Disease Laboratory, Bacterial and Parasitic Disease Division, Department of Animal & Plant Health Research, Animal and Plant Quarantine Agency, Gimcheon 39660, Republic of Korea
| | - Min-Goo Seo
- College of Veterinary Medicine, Kyungpook National University, Daegu 41566, Republic of Korea
| | - Dongmi Kwak
- College of Veterinary Medicine, Kyungpook National University, Daegu 41566, Republic of Korea
| | - SungShik Shin
- College of Veterinary Medicine, Chonnam National University, Gwangju 61186, Republic of Korea
| | - Seung-Hun Lee
- College of Veterinary Medicine, Chungbuk National University, Chungbuk 28644, Republic of Korea.
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Genetic Diversity of Bovine Hemoprotozoa in South Korea. Pathogens 2020; 9:pathogens9090768. [PMID: 32962267 PMCID: PMC7558637 DOI: 10.3390/pathogens9090768] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Revised: 09/12/2020] [Accepted: 09/19/2020] [Indexed: 11/17/2022] Open
Abstract
Tick-borne pathogens cause economically significant diseases in cattle. Theileria spp. are parasitic protozoa and the causative agent of bovine theileriosis. Here we report the distribution and risk factors of bovine Theileria using blood samples taken between 2018 and 2019. Of 737 tested cattle, nine animals (1.2%) were positive for Theileria orientalis infection by 18S rRNA gene amplification. Further analysis of the infected samples using the T. orientalis major piroplasm surface protein (MPSP) gene revealed five different genotypes circulating in the population: Types 1, 2, 3, 7, and N3. To the best of our knowledge, this is the first research to describe the existence of the T. orientalis MPSP genotype N3 in South Korea. Although the prevalence of bovine T. orientalis was low, our study offers data on the geographical distribution and prevalence of bovine Theileria spp. in South Korea. Further studies are warranted to determine the correlation of clinical symptoms with parasite MPSP genotypes. Our data provide epidemiological information to help control bovine theileriosis in South Korea.
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Seo MG, Kwon OD, Kwak D. Genotypic Analysis of Piroplasms and Associated Pathogens from Ticks Infesting Cattle in Korea. Microorganisms 2020; 8:microorganisms8050728. [PMID: 32414173 PMCID: PMC7284522 DOI: 10.3390/microorganisms8050728] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 05/03/2020] [Accepted: 05/12/2020] [Indexed: 12/24/2022] Open
Abstract
Tick-borne pathogens (TBPs) impose an important limitation to livestock production worldwide, especially in subtropical and tropical areas. Earlier studies in Korea have examined TBPs residing in ticks and animals; however, information on multiple TBPs in ticks infesting cattle is lacking. This study assessed the prevalence of TBPs in ticks parasitizing cattle. A total of 576 ticks, including 340 adults and 236 nymphs, were collected from cattle in Korea between 2014 and 2018. All ticks collected were identified as Haemaphysalis longicornis based on their morphological and molecular characteristics. Among piroplasms and other tick-associated pathogens, seven TBP genes, namely Theileria orientalis (5.0%), Anaplasma bovis (2.3%), Anaplasma capra (4.7%), Anaplasma phagocytophilum-like Anaplasma spp. (APL) clades A (1.9%) and B (0.5%), Ehrlichia canis (1.6%), and Candidatus Rickettsia longicornii (17.5%), were detected. Bartonella spp. and severe fever with thrombocytopenia syndrome virus were not found. To our knowledge, this is the first study to report the presence of the pathogens T. orientalis major piroplasm surface protein genotypes 3 and 7, A. capra, and APL in ticks from Korea. Cattle ticks may be maintenance hosts for many TBPs, and veterinary and medical clinicians should be aware of their high probability of infection and clinical complexity in humans.
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Affiliation(s)
- Min-Goo Seo
- Veterinary Drugs and Biologics Division, Animal and Plant Quarantine Agency, 177 Hyeoksin 8-ro, Gimcheon, Gyeongbuk 39660, Korea;
| | - Oh-Deog Kwon
- Department of Veterinary Medicine, College of Veterinary Medicine, Kyungpook National University, 80 Daehak-ro, Buk-gu, Daegu 41566, Korea;
| | - Dongmi Kwak
- Department of Veterinary Medicine, College of Veterinary Medicine, Kyungpook National University, 80 Daehak-ro, Buk-gu, Daegu 41566, Korea;
- Cardiovascular Research Institute, Kyungpook National University, 680 Gukchaebosang-ro, Jung-gu, Daegu 41944, Korea
- Correspondence:
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Kim S, Yu DH, Kang SW, Chae JB, Choi KS, Kim HC, Park BK, Chae JS, Park J. Hematological Changes Associated with Theileria orientalis Infection in Korean Indigenous Cattle. THE KOREAN JOURNAL OF PARASITOLOGY 2017; 55:481-489. [PMID: 29103263 PMCID: PMC5678470 DOI: 10.3347/kjp.2017.55.5.481] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Revised: 05/21/2017] [Accepted: 06/23/2017] [Indexed: 01/18/2023]
Abstract
Tick-borne pathogens can cause serious problems in grazing cattle. However, little information is available on tick-mediated diseases in cattle grazing on mountains. Thus, this study aimed to understand the potential problems related to tick-borne diseases in grazing cattle through the investigation of prevalent tick-transmitted infections, and their associated hematological changes, in terms of season and grazing type in Korean indigenous cattle (=Hanwoo). Hanwoo cattle from 3 regions of the Republic of Korea (=Korea) were either maintained indoors or placed on grassy mountains from spring to fall of 2014 and 2015. Cattle that grazed in mountainous areas showed a greater prevalence of tick-borne infections with an increased Theileria orientalis infection rate (54.7%) compared to that in non-grazing cattle (16.3%) (P<0.001). Accordingly, the red blood cell (RBC) count and hematocrit (HCT) values of grazing cattle were significantly lower than those of non-grazing cattle throughout the season (P<0.05). Moreover, RBC, hemoglobin (Hb), and HCT of T. orientalis-positive group were significantly lower than those of T. orientalis-negative group (P<0.05). T. orientalis is a widespread tick-borne pathogen in Korea. Grazing of cattle in mountainous areas is closely associated with an increase in T. orientalis infection (RR=3.4, P<0.001), and with consequent decreases in RBC count and HCT. Thus, these findings suggest that the Hanwoo cattle in mountainous areas of Korea are at a high risk of infection by T. orientalis, which can lead to hematological alterations. This study highlights the necessity of preventive strategies that target T. orientalis infection.
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Affiliation(s)
- Suhee Kim
- National Institute of Animal Science, Rural Development Administration, Wanju 55365, Korea
| | - Do-Hyeon Yu
- College of Veterinary Medicine, Gyeongsang National University, Jinju 52828, Korea
| | - Sung-Woo Kang
- College of Veterinary Medicine, Chonnam National University, Gwangju 61186, Korea
| | - Jeong-Byoung Chae
- Laboratory of Veterinary Internal Medicine, BK21 PLUS Program for Creative Veterinary Science Research, Research Institute for Veterinary Science and College of Veterinary Medicine, Seoul National University, Seoul 08826, Korea
| | - Kyoung-Seong Choi
- College of Ecology and Environmental Science, Kyungpook National University, Sangju 37224, Korea
| | - Hyeon-Cheol Kim
- College of Veterinary Medicine, Kangwon National University, Chuncheon 24341, Korea
| | - Bae-Keun Park
- College of Veterinary Medicine, Chungnam National University, Daejeon 34134, Korea
| | - Joon-Seok Chae
- Laboratory of Veterinary Internal Medicine, BK21 PLUS Program for Creative Veterinary Science Research, Research Institute for Veterinary Science and College of Veterinary Medicine, Seoul National University, Seoul 08826, Korea
| | - Jinho Park
- College of Veterinary Medicine, Chonbuk National University, Iksan 54596, Korea
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Han YJ, Park J, Lee YS, Chae JS, Yu DH, Park BK, Kim HC, Choi KS. Molecular identification of selected tick-borne pathogens in wild deer and raccoon dogs from the Republic of Korea. VETERINARY PARASITOLOGY- REGIONAL STUDIES AND REPORTS 2017; 7:25-31. [DOI: 10.1016/j.vprsr.2016.12.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Revised: 11/12/2016] [Accepted: 12/01/2016] [Indexed: 10/20/2022]
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Genetic characterization of Theileria orientalis from cattle in the Republic of Korea. Parasitol Res 2016; 116:449-454. [PMID: 27817011 DOI: 10.1007/s00436-016-5316-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Accepted: 10/28/2016] [Indexed: 10/20/2022]
Abstract
Theileria orientalis is the causative agent of benign theileriosis, which is distributed mainly in Asian countries, and causes serious economic losses in the livestock industry. The present study was performed to investigate the epidemiology of T. orientalis infections in cattle in the Republic of Korea (ROK) and to characterize the genetic diversity of T. orientalis based on the major piroplasm surface protein (MPSP) genes. In 2015, between July and August, blood samples were collected from 138 asymptomatic cattle in four different geographical regions (Hoengseong, Jeongeup, Namwon, and Jeju island) in the ROK. In total, 57 blood samples (41.3 %, 57/138) were positive for T. orientalis based on PCR amplification of the MPSP gene. A high prevalence of T. orientalis infection was observed in Jeju island, whereas the infection rate was relatively low in Jeongeup. Phylogenetic analysis showed that isolates identified in this study belonged to four MPSP genotypes, specifically types 1, 2, 3, and 7. The distribution of the four genotypes varied considerably among the four regions; types 1, 2, and 3 were detected in Jeju island, whereas types 1 and 7 were found in Namwon, types 1 and 2 in Jeongeup, and type 2 in Hoengseong. To our knowledge, this is the first report on the identification of type 7 T. orientalis in cattle in the ROK. These results suggest that the MPSP genotypes detected in this study showed genetic diversity related to geographical location. Our findings revealed that the T. orientalis infection rate was relatively high, indicating that T. orientalis infection is closely associated with grazing. Of the four MPSP genotypes, the prevalence of the most pathogenic type 2 was relatively high in the ROK. Therefore, further studies should focus on the development of an effective monitoring and prevention program for T. orientalis.
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Choi KS, Yu DH, Chae JS, Park BK, Yoo JG, Park J. Seasonal changes in hemograms and Theileria orientalis infection rates among Holstein cattle pastured in the mountains in the Republic of Korea. Prev Vet Med 2016; 127:77-83. [PMID: 27094144 DOI: 10.1016/j.prevetmed.2016.03.018] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Revised: 03/24/2016] [Accepted: 03/30/2016] [Indexed: 10/22/2022]
Abstract
In the current study, we compared seasonal changes in complete blood counts (CBCs) and rates of infection with a tick-borne pathogen between Holstein cattle housed indoors and those maintained outside on pasture. There were differences in white blood cell (WBC) parameters, but the changes were not associated with seasons or the housing type. Analysis of red blood cell (RBC) parameters showed lower values in August and November versus March, and in the cattle maintained on pasture versus the housed cattle. In comparison with the RBC count of the housed cattle in March (10.1M/μL), the RBC counts of the pastured cattle were significantly lower in August (7.8M/μL; p<0.01) and November (7.5M/μL; p<0.01). The hematocrit (HCT) also showed a decrease in March (33.5%), August (30.0%, p<0.01) and November (28.5%, p<0.01). According to PCR analysis, the Theileria infection rate among the pastured cattle in March was only 11%, but this rate increased to 22% and 60% in August and November, respectively. The RBC count (7.4M/μL) and HCT (27.7%) values in Theileria-positive pastured cattle in November showed a dramatic decrease compared to those of cattle examined in March. Phylogenetic analysis revealed that these Theileria isolates correspond to T. orientalis. These results suggest that a remarkable increase in tick infestation in mountainous areas in the summer may cause increased rates of infection with T. orientalis, leading to significant changes in the RBC profile after grazing. Therefore, these hematological changes may be associated with T. orientalis infection caused by tick-biting; thus, additional studies on the pathogenicity of T. orientalis are needed.
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Affiliation(s)
- Kyoung-Seong Choi
- College of Ecology and Environmental Science, Kyungpook National University, Sangju 37224, Republic of Korea.
| | - Do-Hyeon Yu
- College of Veterinary Medicine, Chonnam National University, Gwangju 61186, Republic of Korea
| | - Joon-Seok Chae
- Laboratory of Veterinary Internal Medicine, BK21 PLUS Program for Creative Veterinary Science Research, Research Institute for Veterinary Science and College of Veterinary Medicine, Seoul National University, Seoul 08826, Republic of Korea
| | - Bae-Keun Park
- College of Veterinary Medicine, Chungnam National University, Daejeon 34134, Republic of Korea
| | - Jae-Gyu Yoo
- Laboratory of Veterinary Clinics, National Institute of Animal Science Rural Development Administration, Jeonju 54875, Republic of Korea
| | - Jinho Park
- College of Veterinary Medicine, Chonbuk National University, Iksan 54596, Republic of Korea
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Pulford DJ, McFadden A, Hamilton JS, Donald J. Investigation of the index case herd and identification of the genotypes of Theileria orientalis associated with outbreaks of bovine anaemia in New Zealand in 2012. N Z Vet J 2015; 64:21-8. [PMID: 26540640 DOI: 10.1080/00480169.2015.1090355] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
CASE HISTORY AND CLINICAL FINDINGS On 7 September 2012 the Ministry for Primary Industries was notified of a dairy cow with regenerative anaemia (haematocrit (HCT) 0.08 L/L) in a herd of 465 Jersey-Friesian cross cows (index case herd) in the Northland region of New Zealand. Organisms consistent with Theileria spp. were present in red blood cells on a blood smear. No other causes of anaemia were detected following examination of affected cows. Blood samples collected from 29 randomly selected cows on 26 September 2012 showed that 24 (83%) were anaemic (HCT≤0.24 L/L) and therefore fitted the case definition for bovine anaemia associated with Theileria orientalis infection. LABORATORY FINDINGS Using a T. orientalis type-specific PCR assay that targeted the single subunit rRNA gene, all of six animals tested were positive for T. orientalis type Ikeda. Blood samples collected from clinically affected cattle in 11 subsequent outbreaks from throughout the North Island showed that T. orientalis Ikeda type was a common finding, but mixed infections with Chitose type were also identified. In addition, using a PCR assay that targeted the major piroplasm surface gene, T. orientalis type 5 was detected in one cow from the Waikato region. DIAGNOSIS The presence of T. orientalis type Ikeda, as well as type 5, was confirmed in cattle from outbreaks of bovine anaemia in herds throughout the North Island of New Zealand. CLINICAL RELEVANCE Two new types of T. orientalis were identified in this investigation, that were associated with a sudden rise in cases of bovine anaemia. The body of evidence showed that the Ikeda type was implicated as the cause of disease observed in this epidemic.
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Affiliation(s)
- D J Pulford
- a Investigation and Diagnostic Centre , Ministry for Primary Industries , 66 Ward Street, Wallaceville, Upper Hutt 5018 , New Zealand
| | - Amj McFadden
- a Investigation and Diagnostic Centre , Ministry for Primary Industries , 66 Ward Street, Wallaceville, Upper Hutt 5018 , New Zealand
| | - J S Hamilton
- b School of Biological Sciences , Victoria University of Wellington , PO Box 600, Wellington 6140 , New Zealand
| | - J Donald
- c New Zealand Veterinary Pathology , Cnr. Thackeray and Anglesea Streets, Hamilton 3206 , New Zealand
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Pulford DJ, Gias E, Bueno IM, McFadden AMJ. Developing high throughput quantitative PCR assays for diagnosing Ikeda and otherTheileria orientalistypes common to New Zealand in bovine blood samples. N Z Vet J 2015; 64:29-37. [DOI: 10.1080/00480169.2015.1089798] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Development and validation of a quantitative PCR assay using multiplexed hydrolysis probes for detection and quantification of Theileria orientalis isolates and differentiation of clinically relevant subtypes. J Clin Microbiol 2015; 53:941-50. [PMID: 25588653 DOI: 10.1128/jcm.03387-14] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Theileria orientalis is an emerging pathogen of cattle in Asia, Australia, and New Zealand. This organism is a vector-borne hemoprotozoan that causes clinical disease characterized by anemia, abortion, and death, as well as persistent subclinical infections. Molecular methods of diagnosis are preferred due to their sensitivity and utility in differentiating between pathogenic and apathogenic genotypes. Conventional PCR (cPCR) assays for T. orientalis detection and typing are laborious and do not provide an estimate of parasite load. Current real-time PCR assays cannot differentiate between clinically relevant and benign genotypes or are only semiquantitative without a defined clinical threshold. Here, we developed and validated a hydrolysis probe quantitative PCR (qPCR) assay which universally detects and quantifies T. orientalis and identifies the clinically associated Ikeda and Chitose genotypes (UIC assay). Comparison of the UIC assay results with previously validated universal and genotype-specific cPCR results demonstrated that qPCR detects and differentiates T. orientalis with high sensitivity and specificiy. Comparison of quantitative results based on percent parasitemia, determined via blood film analysis and packed cell volume (PCV) revealed significant positive and negative correlations, respectively. One-way analysis of variance (ANOVA) indicated that blood samples from animals with clinical signs of disease contained statistically higher concentrations of T. orientalis DNA than animals with subclinical infections. We propose clinical thresholds to assist in classifying high-, moderate-, and low-level infections and describe how parasite load and the presence of the Ikeda and Chitose genotypes relate to disease.
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Perera PK, Gasser RB, Jabbar A. Assessment of sequence variability in a p23 gene region within and among three genotypes of the Theileria orientalis complex from south-eastern Australia. Ticks Tick Borne Dis 2014; 6:123-8. [PMID: 25468761 DOI: 10.1016/j.ttbdis.2014.10.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Revised: 10/27/2014] [Accepted: 10/29/2014] [Indexed: 11/19/2022]
Abstract
Oriental theileriosis is a tick-borne, protozoan disease of cattle caused by one or more genotypes of Theileria orientalis complex. In this study, we assessed sequence variability in a region of the 23kDa piroplasm membrane protein (p23) gene within and among three T. orientalis genotypes (designated buffeli, chitose and ikeda) in south-eastern Australia. Genomic DNA (n=100) was extracted from blood of infected cattle from various locations endemic for oriental theileriosis and tested by polymerase chain reaction (PCR)-coupled mutation scanning (single-strand conformation polymorphism (SSCP)) and targeted sequencing analysis. Eight distinct sequences represented all DNA samples, and three genotypes were found: buffeli (n=3), chitose (3) and ikeda (2). Nucleotide pairwise comparisons among these eight sequences revealed considerably higher variability among the genotypes (6.6-11.7%) than within them (0-1.9%), indicating that the p23 gene region allows the accurate identification of T. orientalis genotypes. In the future, we will combine this gene with other molecular markers to study the genetic structure of T. orientalis populations in Australasia, which will pave the way to establish a highly sensitive and specific PCR-based assay for genotypic diagnosis of infection and for assessing levels of parasitaemia in cattle.
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Affiliation(s)
- Piyumali K Perera
- Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Victoria, Australia
| | - Robin B Gasser
- Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Victoria, Australia
| | - Abdul Jabbar
- Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Victoria, Australia.
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Sivakumar T, Hayashida K, Sugimoto C, Yokoyama N. Evolution and genetic diversity of Theileria. INFECTION GENETICS AND EVOLUTION 2014; 27:250-63. [PMID: 25102031 DOI: 10.1016/j.meegid.2014.07.013] [Citation(s) in RCA: 137] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2014] [Revised: 07/11/2014] [Accepted: 07/15/2014] [Indexed: 11/16/2022]
Abstract
Theileria parasites infect a wide range of domestic and wild ruminants worldwide, causing diseases with varying degrees of severity. A broad classification, based on the parasite's ability to transform the leukocytes of host animals, divides Theileria into two groups, consisting of transforming and non-transforming species. The evolution of transforming Theileria has been accompanied by drastic changes in its genetic makeup, such as acquisition or expansion of gene families, which are thought to play critical roles in the transformation of host cells. Genetic variation among Theileria parasites is sometimes linked with host specificity and virulence in the parasites. Immunity against Theileria parasites primarily involves cell-mediated immune responses in the host. Immunodominance and major histocompatibility complex class I phenotype-specificity result in a host immunity that is tightly focused and strain-specific. Immune escape in Theileria is facilitated by genetic diversity in its antigenic determinants, which potentially results in a loss of T cell receptor recognition in its host. In the recent past, several reviews have focused on genetic diversity in the transforming species, Theileriaparva and Theileriaannulata. In contrast, genetic diversity in Theileriaorientalis, a benign non-transforming parasite, which occasionally causes disease outbreaks in cattle, has not been extensively examined. In this review, therefore, we provide an outline of the evolution of Theileria, which includes T. orientalis, and discuss the possible mechanisms generating genetic diversity among parasite populations. Additionally, we discuss the potential implications of a genetically diverse parasite population in the context of Theileria vaccine development.
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Affiliation(s)
- Thillaiampalam Sivakumar
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido, Japan; Veterinary Research Institute, Peradeniya, Sri Lanka
| | - Kyoko Hayashida
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido, Japan
| | - Chihiro Sugimoto
- Division of Collaboration and Education, Research Center for Zoonosis Control, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Naoaki Yokoyama
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido, Japan.
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Epidemiological survey following oriental theileriosis outbreaks in Victoria, Australia, on selected cattle farms. Vet Parasitol 2013; 197:509-21. [PMID: 23896063 DOI: 10.1016/j.vetpar.2013.06.023] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2013] [Revised: 06/27/2013] [Accepted: 06/29/2013] [Indexed: 11/21/2022]
Abstract
This study investigated Theileria orientalis following outbreaks of oriental theileriosis in cattle in the state of Victoria, Australia, from September 2010 to January 2012, using traditional and molecular methods of diagnosis. A questionnaire was used to collect epidemiological information from cattle farms. Blood samples (n=301), collected from individual symptomatic and asymptomatic cattle from 19 cattle farms, were examined for the presence of Theileria on stained blood smears and tested using a PCR-based approach, employing a region within the major piroplasm surface protein (MPSP) gene as a marker. The microscopic examination of stained blood smears detected stages consistent with Theileria piroplasms in 28.1% (79/281) of the samples. PCR products were amplified from 70.8% (213/301) of the samples. Mutation scanning analysis of all amplicons displayed seven distinct profiles. Following the direct sequencing of representative amplicons, the genotypes ikeda, chitose, buffeli and type 5 were detected in 91.1%, 32.9%, 2.4% and 1.4% of 213 blood samples, respectively. The distribution of these four genotypes varied among the 19 farms; genotype ikeda was detected on all farms, whereas genotypes chitose, buffeli and type 5 were detected on 14, 3 and 2 farms, respectively. Mix infections with genotypes ikeda and chitose were common (21.6%). Survey results revealed that oriental theileriosis affected mainly beef cows of more than two years of age, prior to calving, and disease was associated with abortion and cow deaths. Future investigations should focus on developing improved tools for investigating and managing oriental theileriosis.
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Kang SW, Doan HTT, Choe SE, Noh JH, Yoo MS, Reddy KE, Kim YH, Kweon CH, Jung SC, Chang KY. Molecular investigation of tick-borne pathogens in ticks from grazing cattle in Korea. Parasitol Int 2013; 62:276-82. [PMID: 23501057 DOI: 10.1016/j.parint.2013.02.002] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2012] [Revised: 01/15/2013] [Accepted: 02/15/2013] [Indexed: 11/28/2022]
Abstract
This study was carried out to identify the tick species that infest grazing cattle and to determine the presence of tick-borne pathogens transmitted by these ticks in Korea. A total of 903 ticks (categorized into 566 tick pools) were collected from five provinces during 2010-2011. The most prevalent tick species was Haemaphysalis longicornis, followed by three Ixodes spp. ticks. The collected ticks were infected with both rickettsial and protozoan pathogens. In all, 469 (82.9%) tick pools tested positive for the Anaplasma/Ehrlichia 16S rRNA gene, whereas 67 (11.8%) were positive for the Babesia/Theileria 18S rRNA gene. Among the rickettsial pathogens, E. canis was detected with the highest rate (22.3%), followed by A. platys (20%), E. chaffeensis (19.4%), E. ewingii (19.3%), Rickettsia sp. (12.4%), A. phagocytophilum (5.5%) and E. muris (0.5%). Among the protozoan pathogens, T. equi was detected with the highest rate (7.2%), followed by T. sergenti/T. buffeli (3.7%) and B. caballi (0.35%). Simultaneous infections with up to seven pathogens were also identified. In particular, ticks infected with rickettsial pathogens were also infected with protozoan pathogens (22 samples). All five provinces investigated infected with tick-borne pathogens.
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Affiliation(s)
- Seung Won Kang
- Parasitology and Insect Disease Research Laboratory, Animal, Plant and Fisheries, Quarantine and Inspection Agency, 480 Anyang 6 dong, Anyang City, Republic of Korea.
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