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Byaruhanga C, Makgabo SM, Choopa CN, Mulandane FC, Vorster I, Troskie M, Chaisi ME, Collins NE. Genetic diversity in Babesia bovis from southern Africa and estimation of B. bovis infection levels in cattle using an optimised quantitative PCR assay. Ticks Tick Borne Dis 2023; 14:102084. [PMID: 36427476 DOI: 10.1016/j.ttbdis.2022.102084] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Revised: 09/22/2022] [Accepted: 11/17/2022] [Indexed: 11/20/2022]
Abstract
Babesia bovis is a causal agent of bovine babesiosis, a disease which leads to mortality and morbidity and impacts the cattle industry worldwide. We amplified, cloned and sequenced the B. bovis merozoite surface antigen-2b (msa-2b) gene (∼940 bp) and the near full-length 18S rRNA gene (∼1600 bp) from cattle samples from South Africa and Mozambique to determine sequence variation between B. bovis parasites in the region. A TaqMan quantitative real-time PCR (qPCR) assay (18S rRNA gene) was optimised for the detection of B. bovis and estimation of parasitaemia in field samples from cattle from southern Africa. Phylogenetic analysis grouped the Msa-2b sequences in six clades and these were 59.7 to 99.6% identical to reference sequences. Sequence variation amongst B. bovis 18S rRNA sequences was found at 2 to 36 positions, and the sequences were 97 to 99% identical to published sequences. Mismatches between the B. bovis 18S rRNA sequences and a previously published qPCR forward primer (BoF) were observed; therefore, we developed a new forward primer (BoF2), and optimised the qPCR assay. Six 10-fold dilution series of B. bovis infected erythrocytes (2 × 108 to 2 × 103 infected red blood cells [iRBC]/ml) were analysed in triplicate in each of six separate qPCR runs, to determine the efficiency of the assay. The qPCR assay amplified the B. bovis 18S rRNA gene with 92.0 to 94.9% efficiency. The detection limit of the qPCR assay was approximately 6 iRBCs/μl. The performance of the optimised assay to diagnose B. bovis in field samples was assessed by testing DNA from 222 field samples of cattle from South Africa and Mozambique using three methods: the optimised qPCR assay, the reverse line blot (RLB) hybridisation assay, and the previously published qPCR assay. The detection rate of B. bovis using the optimised qPCR assay (31.1%, 69/222) was significantly higher (p<0.001) than both that using RLB (20.7%, 46/222) and the previously published qPCR assay (5.4%; 12/222). The B. bovis parasitaemia in samples from infected cattle ranged from 6 iRBCs/μl to 101,852 iRBCs/μl of blood. Our study revealed marked sequence variation between B. bovis parasites from southern Africa. The optimised qPCR assay will be useful in epidemiological studies and clinical diagnosis of B. bovis in southern Africa, and can be used to determine parasitaemia and potential carrier status in cattle populations, which is essential in the control of babesiosis.
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Affiliation(s)
- Charles Byaruhanga
- Vectors and Vector-Borne Diseases Research Programme, Department of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort 0110, South Africa; National Agricultural Research Organisation, P.O. Box 259, Entebbe, Uganda.
| | - S Marcus Makgabo
- Vectors and Vector-Borne Diseases Research Programme, Department of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort 0110, South Africa
| | - Chimvwele N Choopa
- Vectors and Vector-Borne Diseases Research Programme, Department of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort 0110, South Africa; Central Veterinary Research Institute, Ministry of Fisheries and Livestock, P.O Box 33980, Lusaka, Zambia
| | - Fernando C Mulandane
- Vectors and Vector-Borne Diseases Research Programme, Department of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort 0110, South Africa
| | - Ilse Vorster
- Vectors and Vector-Borne Diseases Research Programme, Department of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort 0110, South Africa
| | - Milana Troskie
- Vectors and Vector-Borne Diseases Research Programme, Department of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort 0110, South Africa
| | - Mamohale E Chaisi
- Vectors and Vector-Borne Diseases Research Programme, Department of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort 0110, South Africa; Foundational Biodiversity Science, South African National Biodiversity Institute, 232 Boom Street, Pretoria 0001, South Africa
| | - Nicola E Collins
- Vectors and Vector-Borne Diseases Research Programme, Department of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort 0110, South Africa
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Yu L, Liu Q, Luo W, Zhao J, Alzan HF, He L. The Structural Basis of Babesia orientalis Lactate Dehydrogenase. Front Cell Infect Microbiol 2022; 11:790101. [PMID: 35071043 PMCID: PMC8766848 DOI: 10.3389/fcimb.2021.790101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Accepted: 12/02/2021] [Indexed: 11/13/2022] Open
Abstract
Glycolytic enzymes play a crucial role in the anaerobic glycolysis of apicomplexan parasites for energy generation. Consequently, they are considered as potential targets for new drug development. Previous studies revealed that lactate dehydrogenase (LDH), a glycolytic enzyme, is a potential drug target in different parasites, such as Plasmodium, Toxoplasma, Cryptosporidium, and Piroplasma. Herein, in order to investigate the structural basis of LDH in Babesia spp., we determined the crystal structure of apo Babesia orientalis (Bo) LDH at 2.67-Å resolution in the space group P1. A five-peptide insertion appears in the active pocket loop of BoLDH to create a larger catalytic pocket, like other protozoa (except for Babesia microti LDH) and unlike its mammalian counterparts, and the absence of this extra insertion inactivates BoLDH. Without ligands, the apo BoLDH takes R-state (relaxed) with the active-site loop open. This feature is obviously different from that of allosteric LDHs in T-state (tense) with the active-site loop open. Compared with allosteric LDHs, the extra salt bridges and hydrogen bonds make the subunit interfaces of BoLDH more stable, and that results in the absence of T-state. Interestingly, BoLDH differs significantly from BmLDH, as it exhibits the ability to adapt quickly to the synthetic co-factor APAD+. In addition, the enzymatic activity of BoLDH was inhibited non-competitively by polyphenolic gossypol with a Ki value of 4.25 μM, indicating that BoLDH is sensitive to the inhibition of gossypol and possibly to its new derivative compounds. The current work provides the structural basis of BoLDH for the first time and suggests further investigation on the LDH structure of other Babesia spp. That knowledge would indeed facilitate the screening and designing of new LDH inhibitors to control the intracellular proliferation of Babesia spp.
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Affiliation(s)
- Long Yu
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.,Key Laboratory of Preventive Veterinary Medicine in Hubei Province, Wuhan, China
| | - Qin Liu
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.,Key Laboratory of Preventive Veterinary Medicine in Hubei Province, Wuhan, China
| | - Wanxin Luo
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.,Key Laboratory of Preventive Veterinary Medicine in Hubei Province, Wuhan, China
| | - Junlong Zhao
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.,Key Laboratory of Preventive Veterinary Medicine in Hubei Province, Wuhan, China.,Key Laboratory of Animal Epidemical Disease and Infectious Zoonoses, Ministry of Agriculture, Huazhong Agricultural University, Wuhan, China
| | - Heba F Alzan
- Department of Veterinary Microbiology and Pathology, College of Veterinary Medicine, Washington State University, Pullman, WA, United States.,Parasitology and Animal Diseases Department, National Research Center, Giza, Egypt.,Tick and Tick-Borne Disease Research Unit, National Research Center, Giza, Egypt
| | - Lan He
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.,Key Laboratory of Preventive Veterinary Medicine in Hubei Province, Wuhan, China.,Key Laboratory of Animal Epidemical Disease and Infectious Zoonoses, Ministry of Agriculture, Huazhong Agricultural University, Wuhan, China
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Mans BJ, Pienaar R, Christo Troskie P, Combrink MP. Investigation into limiting dilution and tick transmissibility phenotypes associated with attenuation of the S24 vaccine strain. Parasit Vectors 2019; 12:419. [PMID: 31455385 PMCID: PMC6712794 DOI: 10.1186/s13071-019-3678-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Accepted: 08/21/2019] [Indexed: 12/27/2022] Open
Abstract
Background Babesia bovis is the causal agent of Asiatic redwater, transmitted by the pandemic tick Rhipicephalus (Boophilus) microplus. Disease control may target the tick vector using acaricides or anti-tick vaccines, or the parasite using chemoprophylaxis or anti-parasite vaccines. Current anti-parasite vaccines comprise live blood vaccines using attenuated B. bovis strains. Attenuation is attained by rapid passage that may result in different phenotypes such as reduced virulence, non-transmissibility by the tick vector, inability to sequester in the host (lack of limiting dilution) and limited genetic diversity. Attenuation and phenotypes may be linked to selection of subpopulations during rapid passage. The South African B. bovis S24 vaccine strain comprise a subpopulation that present low virulence, non-transmissibility, lack of limiting dilution phenotype and the presence of a single A558 Bv80 allele. The S24 strain could be co-transmitted with a field strain (05-100) suggesting sexual recombination. The present study investigated the change in phenotype for the S24 vaccine strain during rapid passage and co-transmission. Methods Vaccine phenotype change during passage as well as co-transmissibility was monitored using Bv80 allele specific PCR, limiting dilution and Illumina-based genome sequencing. Results The S24 population could not be rescued from the S16 passage as previously attained suggesting that selection of the S24 vaccine strain was a serendipitous and stochastic event. Passage from S16 to S24 also resulted in loss of the limiting dilution phenotype. Genome sequencing indicated sexual recombination during co-transmission with the 05-100 field strain. Analysis of the recombinant strain indicate that VESA1, smORF and SBP2 family members are present and may be responsible for the limiting dilution phenotypes, while various regions may also be responsible for the tick transmission phenotype. Conclusions The molecular basis for tick transmission and limiting dilution phenotypes may be defined in future using selection based on these traits in combination with sexual recombination.![]()
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Affiliation(s)
- Ben J Mans
- Epidemiology, Parasites and Vectors, ARC-Onderstepoort Veterinary Institute, Private Bag X05, Onderstepoort, 0110, South Africa. .,Department of Life and Consumer Sciences, University of South Africa, Florida, South Africa.
| | - Ronel Pienaar
- Epidemiology, Parasites and Vectors, ARC-Onderstepoort Veterinary Institute, Private Bag X05, Onderstepoort, 0110, South Africa
| | - P Christo Troskie
- Epidemiology, Parasites and Vectors, ARC-Onderstepoort Veterinary Institute, Private Bag X05, Onderstepoort, 0110, South Africa
| | - Michael P Combrink
- Epidemiology, Parasites and Vectors, ARC-Onderstepoort Veterinary Institute, Private Bag X05, Onderstepoort, 0110, South Africa
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