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Hakimi H, Yamagishi J, Kawazu SI, Asada M. Advances in understanding red blood cell modifications by Babesia. PLoS Pathog 2022; 18:e1010770. [PMID: 36107982 PMCID: PMC9477259 DOI: 10.1371/journal.ppat.1010770] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Babesia are tick-borne protozoan parasites that can infect livestock, pets, wildlife animals, and humans. In the mammalian host, they invade and multiply within red blood cells (RBCs). To support their development as obligate intracellular parasites, Babesia export numerous proteins to modify the RBC during invasion and development. Such exported proteins are likely important for parasite survival and pathogenicity and thus represent candidate drug or vaccine targets. The availability of complete genome sequences and the establishment of transfection systems for several Babesia species have aided the identification and functional characterization of exported proteins. Here, we review exported Babesia proteins; discuss their functions in the context of immune evasion, cytoadhesion, and nutrient uptake; and highlight possible future topics for research and application in this field.
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Affiliation(s)
- Hassan Hakimi
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido, Japan
- Department of Veterinary Pathobiology, College of Veterinary Medicine, Texas A&M University, College Station, Texas, United States of America
- * E-mail: (HH); (MA)
| | - Junya Yamagishi
- Division of Collaboration and Education, International Institute for Zoonosis Control, Hokkaido University, Sapporo, Japan
| | - Shin-ichiro Kawazu
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido, Japan
| | - Masahito Asada
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido, Japan
- * E-mail: (HH); (MA)
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Allred DR. Integration of DNA Repair, Antigenic Variation, Cytoadhesion, and Chance in Babesia Survival: A Perspective. Front Cell Infect Microbiol 2022; 12:869696. [PMID: 35493746 PMCID: PMC9047050 DOI: 10.3389/fcimb.2022.869696] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Accepted: 03/24/2022] [Indexed: 11/13/2022] Open
Abstract
Apicomplexan parasites live in hostile environments in which they are challenged chemically and their hosts attempt in many ways to kill them. In response, the parasites have evolved multiple mechanisms that take advantage of these challenges to enhance their survival. Perhaps the most impressive example is the evolutionary co-option of DNA repair mechanisms by the parasites as a means to rapidly manipulate the structure, antigenicity, and expression of the products of specific multigene families. The purpose of variant proteins that mediate cytoadhesion has long been thought to be primarily the avoidance of splenic clearance. Based upon known biology, I present an alternative perspective in which it is survival of the oxidative environment within which Babesia spp. parasites live that has driven integration of DNA repair, antigenic variation, and cytoadhesion, and speculate on how genome organization affects that integration. This perspective has ramifications for the development of parasite control strategies.
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Affiliation(s)
- David R. Allred
- Department of Infectious Diseases and Immunology, University of Florida, Gainesville, FL, United States
- Genetics Institute, University of Florida, Gainesville, FL, United States
- Emerging Pathogens Institute, University of Florida, Gainesville, FL, United States
- *Correspondence: David R. Allred,
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Mack EA, Tagliamonte MS, Xiao YP, Quesada S, Allred DR. Babesia bovis Rad51 ortholog influences switching of ves genes but is not essential for segmental gene conversion in antigenic variation. PLoS Pathog 2020; 16:e1008772. [PMID: 32866214 PMCID: PMC7485966 DOI: 10.1371/journal.ppat.1008772] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 09/11/2020] [Accepted: 08/13/2020] [Indexed: 01/04/2023] Open
Abstract
The tick-borne apicomplexan parasite, Babesia bovis, a highly persistent bovine pathogen, expresses VESA1 proteins on the infected erythrocyte surface to mediate cytoadhesion. The cytoadhesion ligand, VESA1, which protects the parasite from splenic passage, is itself protected from a host immune response by rapid antigenic variation. B. bovis relies upon segmental gene conversion (SGC) as a major mechanism to vary VESA1 structure. Gene conversion has been considered a form of homologous recombination (HR), a process for which Rad51 proteins are considered pivotal components. This could make BbRad51 a choice target for development of inhibitors that both interfere with parasite genome integrity and disrupt HR-dependent antigenic variation. Previously, we knocked out the Bbrad51 gene from the B. bovis haploid genome, resulting in a phenotype of sensitivity to methylmethane sulfonate (MMS) and apparent loss of HR-dependent integration of exogenous DNA. In a further characterization of BbRad51, we demonstrate here that ΔBbrad51 parasites are not more sensitive than wild-type to DNA damage induced by γ-irradiation, and repair their genome with similar kinetics. To assess the need for BbRad51 in SGC, RT-PCR was used to observe alterations to a highly variant region of ves1α transcripts over time. Mapping of these amplicons to the genome revealed a significant reduction of in situ transcriptional switching (isTS) among ves loci, but not cessation. By combining existing pipelines for analysis of the amplicons, we demonstrate that SGC continues unabated in ΔBbrad51 parasites, albeit at an overall reduced rate, and a reduction in SGC tract lengths was observed. By contrast, no differences were observed in the lengths of homologous sequences at which recombination occurred. These results indicate that, whereas BbRad51 is not essential to babesial antigenic variation, it influences epigenetic control of ves loci, and its absence significantly reduces successful variation. These results necessitate a reconsideration of the likely enzymatic mechanism(s) underlying SGC and suggest the existence of additional targets for development of small molecule inhibitors. B. bovis establishes highly persistent infections in cattle, in part by using cytoadhesion to avoid passage through the spleen. While protective, a host antibody response targeting the cytoadhesion ligand is quickly rendered ineffective by antigenic variation. In B. bovis, antigenic variation relies heavily upon segmental gene conversion (SGC), presumed to be a form of homologous recombination (HR), to generate variants. As Rad51 is generally considered essential to HR, we investigated its contribution to SGC. While diminishing the parasite’s capacity for HR-dependent integration of exogenous DNA, the loss of BbRad51 did not affect the parasite’s sensitivity to ionizing radiation, overall genome stability, or competence for SGC. Instead, loss of BbRad51 diminished the extent of in situ transcriptional switching (isTS) among ves gene loci, the accumulation of SGC recombinants, and the mean lengths of SGC sequence tracts. Given the overall reductions in VESA1 variability, compromise of the parasite’s capacity for in vivo persistence is predicted.
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Affiliation(s)
- Erin A. Mack
- Department of Infectious Diseases and Immunology, University of Florida, Gainesville, Florida, United States of America
| | - Massimiliano S. Tagliamonte
- Department of Pathology, Immunology, and Laboratory Medicine, University of Florida, Gainesville, Florida, United States of America
- Emerging Pathogens Institute, University of Florida, Gainesville, Florida, United States of America
| | - Yu-Ping Xiao
- Department of Infectious Diseases and Immunology, University of Florida, Gainesville, Florida, United States of America
| | - Samantha Quesada
- Department of Infectious Diseases and Immunology, University of Florida, Gainesville, Florida, United States of America
| | - David R. Allred
- Department of Infectious Diseases and Immunology, University of Florida, Gainesville, Florida, United States of America
- Department of Pathology, Immunology, and Laboratory Medicine, University of Florida, Gainesville, Florida, United States of America
- Emerging Pathogens Institute, University of Florida, Gainesville, Florida, United States of America
- Genetics Institute, University of Florida, Gainesville, Florida, United States of America
- * E-mail:
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Allred DR. Variable and Variant Protein Multigene Families in Babesia bovis Persistence. Pathogens 2019; 8:pathogens8020076. [PMID: 31212587 PMCID: PMC6630957 DOI: 10.3390/pathogens8020076] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Revised: 06/03/2019] [Accepted: 06/07/2019] [Indexed: 11/16/2022] Open
Abstract
Cattle infected with Babesia bovis face a bifurcated fate: Either die of the severe acute infection, or survive and carry for many years a highly persistent but generally asymptomatic infection. In this review, the author describes known and potential contributions of three variable or highly variant multigene-encoded families of proteins to persistence in the bovine host, and the mechanisms by which variability arises among these families. Ramifications arising from this variability are discussed.
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Affiliation(s)
- David R Allred
- Department of Infectious Diseases and Immunology, University of Florida, Gainesville, FL 32611, USA.
- Emerging Pathogens Institute, University of Florida, Gainesville, FL 32611, USA.
- Genetics Institute, University of Florida, Gainesville, FL 32611, USA.
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Jackson AP. Gene family phylogeny and the evolution of parasite cell surfaces. Mol Biochem Parasitol 2016; 209:64-75. [DOI: 10.1016/j.molbiopara.2016.03.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Revised: 03/18/2016] [Accepted: 03/19/2016] [Indexed: 11/30/2022]
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Jackson AP, Otto TD, Darby A, Ramaprasad A, Xia D, Echaide IE, Farber M, Gahlot S, Gamble J, Gupta D, Gupta Y, Jackson L, Malandrin L, Malas TB, Moussa E, Nair M, Reid AJ, Sanders M, Sharma J, Tracey A, Quail MA, Weir W, Wastling JM, Hall N, Willadsen P, Lingelbach K, Shiels B, Tait A, Berriman M, Allred DR, Pain A. The evolutionary dynamics of variant antigen genes in Babesia reveal a history of genomic innovation underlying host-parasite interaction. Nucleic Acids Res 2014; 42:7113-31. [PMID: 24799432 PMCID: PMC4066756 DOI: 10.1093/nar/gku322] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Babesia spp. are tick-borne, intraerythrocytic hemoparasites that use antigenic variation to resist host immunity, through sequential modification of the parasite-derived variant erythrocyte surface antigen (VESA) expressed on the infected red blood cell surface. We identified the genomic processes driving antigenic diversity in genes encoding VESA (ves1) through comparative analysis within and between three Babesia species, (B. bigemina, B. divergens and B. bovis). Ves1 structure diverges rapidly after speciation, notably through the evolution of shortened forms (ves2) from 5′ ends of canonical ves1 genes. Phylogenetic analyses show that ves1 genes are transposed between loci routinely, whereas ves2 genes are not. Similarly, analysis of sequence mosaicism shows that recombination drives variation in ves1 sequences, but less so for ves2, indicating the adoption of different mechanisms for variation of the two families. Proteomic analysis of the B. bigemina PR isolate shows that two dominant VESA1 proteins are expressed in the population, whereas numerous VESA2 proteins are co-expressed, consistent with differential transcriptional regulation of each family. Hence, VESA2 proteins are abundant and previously unrecognized elements of Babesia biology, with evolutionary dynamics consistently different to those of VESA1, suggesting that their functions are distinct.
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Affiliation(s)
- Andrew P Jackson
- Department of Infection Biology, Institute of Infection and Global Health, University of Liverpool, Liverpool Science Park Ic2, 146 Brownlow Hill, Liverpool L3 5RF, UK
| | - Thomas D Otto
- Pathogen Genomics Group, Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge CB10 1SA, UK
| | - Alistair Darby
- Department of Functional and Comparative Genomics, Institute of Integrative Biology, University of Liverpool, Crown Street, Liverpool L69 7ZB, UK
| | - Abhinay Ramaprasad
- Computational Bioscience Research Center, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia
| | - Dong Xia
- Department of Infection Biology, Institute of Infection and Global Health, University of Liverpool, Liverpool Science Park Ic2, 146 Brownlow Hill, Liverpool L3 5RF, UK
| | | | - Marisa Farber
- Centro Nacional de Investigaciones Agropecuarias, Instituto de Biotecnología INTA, Buenos Aires, Argentina
| | - Sunayna Gahlot
- Bioinformatics Laboratory, Structural and Computational Biology Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi 110 067, India
| | - John Gamble
- Pathogen Genomics Group, Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge CB10 1SA, UK
| | - Dinesh Gupta
- Bioinformatics Laboratory, Structural and Computational Biology Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi 110 067, India
| | - Yask Gupta
- Bioinformatics Laboratory, Structural and Computational Biology Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi 110 067, India
| | - Louise Jackson
- Department of Agriculture, Fisheries and Forestry, Biosecurity Sciences Laboratory, 39 Kessels Road, Coopers Plains, Queensland 4108, Australia
| | - Laurence Malandrin
- UMR1300 INRA/Oniris Biology, Epidemiology and Risk Analysis in Animal Health, BP 40706, F-44307 Nantes, France
| | - Tareq B Malas
- Computational Bioscience Research Center, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia
| | - Ehab Moussa
- Computational Bioscience Research Center, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia
| | - Mridul Nair
- Computational Bioscience Research Center, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia
| | - Adam J Reid
- Pathogen Genomics Group, Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge CB10 1SA, UK
| | - Mandy Sanders
- Pathogen Genomics Group, Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge CB10 1SA, UK
| | - Jyotsna Sharma
- FG Parasitologie, Philipps Universität Marburg, Karl von Frisch Strasse 8, 35043 Marburg, Germany
| | - Alan Tracey
- Pathogen Genomics Group, Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge CB10 1SA, UK
| | - Mike A Quail
- Pathogen Genomics Group, Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge CB10 1SA, UK
| | - William Weir
- FG Parasitologie, Philipps Universität Marburg, Karl von Frisch Strasse 8, 35043 Marburg, Germany
| | - Jonathan M Wastling
- Department of Infection Biology, Institute of Infection and Global Health, University of Liverpool, Liverpool Science Park Ic2, 146 Brownlow Hill, Liverpool L3 5RF, UK
| | - Neil Hall
- Department of Functional and Comparative Genomics, Institute of Integrative Biology, University of Liverpool, Crown Street, Liverpool L69 7ZB, UK
| | - Peter Willadsen
- Department of Agriculture, Fisheries and Forestry, Biosecurity Sciences Laboratory, 39 Kessels Road, Coopers Plains, Queensland 4108, Australia
| | - Klaus Lingelbach
- FG Parasitologie, Philipps Universität Marburg, Karl von Frisch Strasse 8, 35043 Marburg, Germany
| | - Brian Shiels
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, 464 Bearsden Road, Glasgow G61 1QH, UK
| | - Andy Tait
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, 464 Bearsden Road, Glasgow G61 1QH, UK
| | - Matt Berriman
- Pathogen Genomics Group, Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge CB10 1SA, UK
| | - David R Allred
- Department of Infectious Diseases and Pathology, and Genetics Institute, University of Florida, PO Box 110880, 2015 SW 16th Avenue, Gainesville FL 33611-0880, USA
| | - Arnab Pain
- Computational Bioscience Research Center, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia
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Ríos-Tobón S, Gutiérrez-Builes LA, Ríos-Osorio LA. Assessing bovine babesiosis in Rhipicephalus (Boophilus) microplus ticks and 3 to 9-month-old cattle in the middle Magdalena region, Colombia. PESQUISA VETERINARIA BRASILEIRA 2014. [DOI: 10.1590/s0100-736x2014000400002] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Pedroni MJ, Sondgeroth KS, Gallego-Lopez GM, Echaide I, Lau AOT. Comparative transcriptome analysis of geographically distinct virulent and attenuated Babesia bovis strains reveals similar gene expression changes through attenuation. BMC Genomics 2013; 14:763. [PMID: 24195453 PMCID: PMC3826834 DOI: 10.1186/1471-2164-14-763] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Accepted: 10/30/2013] [Indexed: 11/23/2022] Open
Abstract
Background Loss of virulence is a phenotypic adaptation commonly seen in prokaryotic and eukaryotic pathogens. This mechanism is not well studied, especially in organisms with multiple host and life cycle stages such as Babesia, a tick-transmitted hemoparasite of humans and animals. B. bovis, which infects cattle, has naturally occurring virulent strains that can be reliably attenuated in vivo. Previous studies suggest the virulence loss mechanism may involve post-genomic modification. We investigated the transcriptome profiles of two geographically distinct B. bovis virulent and attenuated strain pairs to better understand virulence loss and to gain insight into pathogen adaptation strategies. Results Expression microarray and RNA-sequencing approaches were employed to compare transcriptome profiles of two B. bovis strain pairs, with each pair consisting of a virulent parental and its attenuated derivative strain. Differentially regulated transcripts were identified within each strain pair. These included genes encoding for VESA1, SmORFs, undefined membrane and hypothetical proteins. The majority of individual specific gene transcripts differentially regulated within a strain were not shared between the two strains. There was a disproportionately greater number of ves genes upregulated in the virulent parental strains. When compared with their attenuated derivatives, divergently oriented ves genes were included among the upregulated ves genes in the virulent strains, while none of the upregulated ves genes in the attenuated derivatives were oriented head to head. One gene family whose specific members were consistently and significantly upregulated in expression in both attenuated strains was spherical body protein (SBP) 2 encoding gene where SBP2 truncated copies 7, 9 and 11 transcripts were all upregulated. Conclusions We conclude that ves heterodimer pair upregulation and overall higher frequency of ves gene expressions in the virulent strains is consistent with the involvement of this gene family in virulence. This is logical given the role of VESA1 proteins in cytoadherence of infected cells to endothelial cells. However, upregulation of some ves genes in the attenuated derivatives suggests that the consequence of upregulation is gene-specific. Furthermore, upregulation of the spherical body protein 2 gene family may play a role in the attenuated phenotype. Exactly how these two gene families may contribute to the loss or gain of virulence is discussed.
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Affiliation(s)
| | | | | | | | - Audrey O T Lau
- Program of Genomics, Department of Veterinary Microbiology & Pathology, College of Veterinary Medicine, Washington State University, ADBF 4043, Pullman, WA, , 99164, USA.
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Unusual chromatin structure associated with monoparalogous transcription of the Babesia bovis ves multigene family. Int J Parasitol 2012. [PMID: 23178996 DOI: 10.1016/j.ijpara.2012.10.018] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Rapid antigenic variation in Babesia bovis involves the variant erythrocyte surface antigen-1 (VESA1), a heterodimeric protein with subunits encoded by two branches of the ves multigene family. The ves1α and ves1β gene pair encoding VESA1a and 1b, respectively, are transcribed in a monoparalogous manner from a single locus of active ves transcription (LAT), just one of many quasi-palindromic ves loci. To determine whether this organization plays a role in transcriptional regulation, chromatin structure was first assessed. Limited treatment of isolated nuclei with micrococcal nuclease to assay nucleosomal patterning revealed a periodicity of 156-159 bp in both bulk chromatin and specific gene coding regions. This pattern also was maintained in the intergenic regions (IGr) of non-transcribed ves genes. In contrast, the LAT IGr adopts a unique pattern, yielding an apparent cluster of five closely-spaced hypersensitive sites flanked by regions of reduced nucleosomal occupancy. ves loci fall into three patterns of overall sensitivity to micrococcal nuclease or DNase I digestion, with only the LAT being consistently very sensitive. Non-transcribed ves genes are inconsistent in their sensitivity to the two enzymatic probes. Non-linear DNA structure in chromatin was investigated to determine whether unique structure arising as a result of the quasi-palindromic nature of the LAT may effect transcriptional control. The in vitro capacity of ves IGr sequences to adopt stable higher-order DNA structure is demonstrated here, but the presence of such structure in vivo was not supported. Based upon these results a working model is proposed for the chromatin structural remodeling responsible for the sequential expression of ves multigene family members from divergently-organized loci.
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Characterization of the unusual bidirectional ves promoters driving VESA1 expression and associated with antigenic variation in Babesia bovis. EUKARYOTIC CELL 2012; 11:260-9. [PMID: 22286091 DOI: 10.1128/ec.05318-11] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Rapid clonal antigenic variation in Babesia bovis involves the variant erythrocyte surface antigen-1 (VESA1) protein expressed on the infected-erythrocyte surface. Because of the significance of this heterodimeric protein for demonstrated mechanisms of parasite survival and virulence, there is a need to understand how expression of the ves multigene family encoding this protein is controlled. As an initial step toward this goal, we present here initial characterization of the ves promoter driving transcription of VESA1a and -1b subunits. A series of transfection constructs containing various sequence elements from the in vivo locus of active ves transcription (LAT) were used to drive expression of the firefly luciferase gene in a dual luciferase-normalized assay. The results of this approach reveal the presence of two bidirectional promoter activities within the 434-bp intergenic region (IGr), influenced by putative regulatory sequences embedded within the flanking ves1α and ves1β genes. Repressor-like effects on the apposing gene were observed for intron 1 of both ves1α and ves1β. This effect is apparently not dependent upon intronic promoter activity and acts only in cis. The expression of genes within the ves family is likely modulated by local elements embedded within ves coding sequences outside the intergenic promoter region in concert with chromatin modifications. These results provide a framework to help us begin to understand gene regulation during antigenic variation in B. bovis.
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Ferreri LM, Brayton KA, Sondgeroth KS, Lau AO, Suarez CE, McElwain TF. Expression and strain variation of the novel "small open reading frame" (smorf) multigene family in Babesia bovis. Int J Parasitol 2011; 42:131-8. [PMID: 22138017 PMCID: PMC3459096 DOI: 10.1016/j.ijpara.2011.10.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2011] [Revised: 09/11/2011] [Accepted: 10/05/2011] [Indexed: 11/19/2022]
Abstract
Small open reading frame (smorf) genes comprise the second largest Babesia bovis multigene family. All known 44 variant smorf genes are located in close chromosomal proximity to ves1 genes, which encode proteins that mediate cytoadhesion and contribute to immune evasion. In this study, we characterised the general topology of smorf genes and investigated the gene repertoire, transcriptional profile and SMORF expression in two distinct strains, T2Bo and Mo7. Sequence analysis using degenerate primers identified additional smorf genes in each strain and demonstrated that the smorf gene repertoire varies between strains, with conserved and unique genes in both. Smorf genes have multiple semi-conserved and variable blocks, and a large hypervariable insertion in 20 of the 44 genes defines two major branches of the family, termed smorf A and smorf B. A total of 32 smorf genes are simultaneously transcribed in T2Bo strain B. bovis merozoites obtained from deep brain tissue of an acutely infected animal. SMORF peptide-specific antiserum bound in immunoblots to multiple proteins with a range of sizes predicted by smorf genes, confirming translation of smorf gene products from these transcripts. These results indicate that the smorf multigene family is larger than previously described and demonstrate that smorf genes are expressed and are undergoing variation, both within strains and in a lineage-specific pattern independent of strain specificity. The function of these novel proteins is unknown.
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Affiliation(s)
- Lucas M. Ferreri
- Department of Veterinary Microbiology and Pathology and School for Global Animal Health, College of Veterinary Medicine, Washington State University, Pullman, WA 99164-6040, USA
| | - Kelly A. Brayton
- Department of Veterinary Microbiology and Pathology and School for Global Animal Health, College of Veterinary Medicine, Washington State University, Pullman, WA 99164-6040, USA
| | - Kerry S. Sondgeroth
- Department of Veterinary Microbiology and Pathology and School for Global Animal Health, College of Veterinary Medicine, Washington State University, Pullman, WA 99164-6040, USA
| | - Audrey O.T. Lau
- Department of Veterinary Microbiology and Pathology and School for Global Animal Health, College of Veterinary Medicine, Washington State University, Pullman, WA 99164-6040, USA
| | - Carlos E. Suarez
- Animal Disease Research Unit, United States Department of Agriculture, Agricultural Research Service, Pullman, WA 99164, USA
| | - Terry F. McElwain
- Department of Veterinary Microbiology and Pathology and School for Global Animal Health, College of Veterinary Medicine, Washington State University, Pullman, WA 99164-6040, USA
- Corresponding author. Tel.: +1 509 335 6342; fax: +1 509 335 7424.
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Gohil S, Kats LM, Sturm A, Cooke BM. Recent insights into alteration of red blood cells by Babesia bovis: moovin' forward. Trends Parasitol 2010; 26:591-9. [PMID: 20598944 DOI: 10.1016/j.pt.2010.06.012] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2010] [Revised: 06/07/2010] [Accepted: 06/08/2010] [Indexed: 10/19/2022]
Abstract
Over the past decade or so, our understanding of the biology of apicomplexan parasites has increased dramatically, particularly in the case of malaria. Notable achievements are the availability of complete genome sequences, transcriptome and proteome profiles and the establishment of in vitro transfection techniques for asexual-stage malaria parasites. Interestingly, despite their major economic importance and striking similarities with malaria, Babesia parasites have been relatively ignored, but change is on the horizon. Here, we bring together recent work on Babesia bovis parasites which are beginning to unravel the molecular mechanisms that underlie the pathogenesis of babesiosis and highlight some opportunities and challenges that lie ahead.
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Affiliation(s)
- Sejal Gohil
- Department of Microbiology, Monash University, Victoria, Australia
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Xiao YP, Al-Khedery B, Allred DR. The Babesia bovis VESA1 virulence factor subunit 1b is encoded by the 1beta branch of the ves multigene family. Mol Biochem Parasitol 2010; 171:81-8. [PMID: 20226217 DOI: 10.1016/j.molbiopara.2010.03.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2009] [Revised: 02/18/2010] [Accepted: 03/01/2010] [Indexed: 10/19/2022]
Abstract
Babesia bovis, an intraerythrocytic parasite of cattle, establishes persistent infections of extreme duration. This is accomplished, at least in part, through rapid antigenic variation of a heterodimeric virulence factor, the variant erythrocyte surface antigen-1 (VESA1) protein. Previously, the VESA1a subunit was demonstrated to be encoded by a 1alpha member of the ves multigene family. Since its discovery the 1beta branch of this multigene family has been hypothesized to encode the VESA1b polypeptide, but formal evidence for this connection has been lacking. Here, we provide evidence that products of ves1beta genes are rapidly variant in antigenicity and size-polymorphic, matching known VESA1b polypeptides. Importantly, the ves1beta-encoded antigens are co-precipitated with VESA1a during immunoprecipitation with anti-VESA1a monoclonal antibodies, and antisera to ves1beta polypeptide co-precipitate VESA1a. Further, the ves1beta-encoded antigens significantly co-localize with VESA1a on the infected-erythrocyte membrane surface of live cells. These characteristics all match known properties of VESA1b, allowing us to conclude that the ves1beta gene divergently apposing the ves1beta gene within the locus of active ves transcription (LAT) encodes the 1b subunit of the VESA1 cytoadhesion ligand. However, the extent and stoichiometry of VESA1a and 1b co-localization on the surface of individual cells is quite variable, implicating competing effects on transcription, translation, or trafficking of the two subunits. These results provide essential information facilitating further investigation into this parasite virulence factor.
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Affiliation(s)
- Yu-Ping Xiao
- University of Florida, Department of Infectious Diseases and Pathology, Gainesville, FL, USA
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