Identification and antigenicity of the Babesia caballi spherical body protein 4 (SBP4)

Abstract Background The tick-borne intra-erythrocytic apicomplexan Babesia caballi is one of the etiological agents of equine babesiosis, an economically important disease of equids in most tropical and subtropical areas of the world. Discovering candidate antigens for improved diagnostic tools and...

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Main Authors: Mona S. Mahmoud, Omnia M. Kandil, Nadia T. Abu El-Ezz, Seham H. M. Hendawy, Bassma S. M. Elsawy, Donald P. Knowles, Reginaldo G. Bastos, Lowell S. Kappmeyer, Jacob M. Laughery, Heba F. Alzan, Carlos E. Suarez
Format: Article
Language:English
Published: BMC 2020-07-01
Series:Parasites & Vectors
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Online Access:http://link.springer.com/article/10.1186/s13071-020-04241-9
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author Mona S. Mahmoud
Omnia M. Kandil
Nadia T. Abu El-Ezz
Seham H. M. Hendawy
Bassma S. M. Elsawy
Donald P. Knowles
Reginaldo G. Bastos
Lowell S. Kappmeyer
Jacob M. Laughery
Heba F. Alzan
Carlos E. Suarez
author_facet Mona S. Mahmoud
Omnia M. Kandil
Nadia T. Abu El-Ezz
Seham H. M. Hendawy
Bassma S. M. Elsawy
Donald P. Knowles
Reginaldo G. Bastos
Lowell S. Kappmeyer
Jacob M. Laughery
Heba F. Alzan
Carlos E. Suarez
author_sort Mona S. Mahmoud
collection DOAJ
description Abstract Background The tick-borne intra-erythrocytic apicomplexan Babesia caballi is one of the etiological agents of equine babesiosis, an economically important disease of equids in most tropical and subtropical areas of the world. Discovering candidate antigens for improved diagnostic tools and vaccines remains needed for controlling equine babesiosis. This study describes the B. caballi sbp4 (Bcsbp4) gene and protein (BcSBP4) and analyzes its antigenicity in infected equids. Methods BLAST searches of an uncurated B. caballi assembly genome using the B. bovis SBP4 as a query were carried out, followed by PCR amplification and sequencing of a newly identified BcSBP4. Characterization of this novel gene and protein was performed by bioinformatics analysis, western blots, immunofluorescence (IFA) and an in vitro neutralization test using anti SBP4 peptide antibodies. Antigenicity of recombinant BcSBP4 (rBcSBP4) was tested with sera from field animals (n = 18) using an indirect ELISA (iELISA). Results Babesia caballi genome searches using B. bovis SBP4 as a query allowed identification of a novel gene termed Bcsbp4. The Bcsbp4 gene encodes for a protein of 30.58 kDa, which is fully conserved among B. caballi isolates from USA and Egypt. Bioinformatics analysis indicates that BcSBP4 contains a signal peptide and lacks additional transmembrane domains. Expression of BcSBP4 in blood stages of B. caballi was confirmed by western blot and IFA using antibodies against synthetic peptides representing putative B-cell epitopes of BcSBP4 predicted by in silico analysis. In vitro neutralization tests using anti-BcSBP4 peptide antibodies showed a marginal, but statistically significant inhibitory effect on the infectivity of B. caballi merozoites in horse red blood cells. Sera from eight B. caballi-infected equids, but none out of ten negative equid control sera, gave a positive signal in an rBcSBP4 based iELISA. Conclusions The Bcsbp4 gene is expressed in B. caballi blood stages. The BcSBP4 protein is a potential candidate for developing a novel serological test that could detect B. caballi infection in equids in tropical and subtropical countries worldwide.
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spelling doaj.art-0754b664ffc94e6697e4ed88c28afc6f2022-12-21T19:33:44ZengBMCParasites & Vectors1756-33052020-07-0113111010.1186/s13071-020-04241-9Identification and antigenicity of the Babesia caballi spherical body protein 4 (SBP4)Mona S. Mahmoud0Omnia M. Kandil1Nadia T. Abu El-Ezz2Seham H. M. Hendawy3Bassma S. M. Elsawy4Donald P. Knowles5Reginaldo G. Bastos6Lowell S. Kappmeyer7Jacob M. Laughery8Heba F. Alzan9Carlos E. Suarez10Parasitology and Animal Diseases Department, National Research CenterParasitology and Animal Diseases Department, National Research CenterParasitology and Animal Diseases Department, National Research CenterParasitology and Animal Diseases Department, National Research CenterParasitology and Animal Diseases Department, National Research CenterDepartment of Veterinary Microbiology and Pathology, College of Veterinary Medicine, Washington State UniversityDepartment of Veterinary Microbiology and Pathology, College of Veterinary Medicine, Washington State UniversityAnimal Disease Research Unit, United States Department of Agricultural-Agricultural Research ServiceDepartment of Veterinary Microbiology and Pathology, College of Veterinary Medicine, Washington State UniversityParasitology and Animal Diseases Department, National Research CenterDepartment of Veterinary Microbiology and Pathology, College of Veterinary Medicine, Washington State UniversityAbstract Background The tick-borne intra-erythrocytic apicomplexan Babesia caballi is one of the etiological agents of equine babesiosis, an economically important disease of equids in most tropical and subtropical areas of the world. Discovering candidate antigens for improved diagnostic tools and vaccines remains needed for controlling equine babesiosis. This study describes the B. caballi sbp4 (Bcsbp4) gene and protein (BcSBP4) and analyzes its antigenicity in infected equids. Methods BLAST searches of an uncurated B. caballi assembly genome using the B. bovis SBP4 as a query were carried out, followed by PCR amplification and sequencing of a newly identified BcSBP4. Characterization of this novel gene and protein was performed by bioinformatics analysis, western blots, immunofluorescence (IFA) and an in vitro neutralization test using anti SBP4 peptide antibodies. Antigenicity of recombinant BcSBP4 (rBcSBP4) was tested with sera from field animals (n = 18) using an indirect ELISA (iELISA). Results Babesia caballi genome searches using B. bovis SBP4 as a query allowed identification of a novel gene termed Bcsbp4. The Bcsbp4 gene encodes for a protein of 30.58 kDa, which is fully conserved among B. caballi isolates from USA and Egypt. Bioinformatics analysis indicates that BcSBP4 contains a signal peptide and lacks additional transmembrane domains. Expression of BcSBP4 in blood stages of B. caballi was confirmed by western blot and IFA using antibodies against synthetic peptides representing putative B-cell epitopes of BcSBP4 predicted by in silico analysis. In vitro neutralization tests using anti-BcSBP4 peptide antibodies showed a marginal, but statistically significant inhibitory effect on the infectivity of B. caballi merozoites in horse red blood cells. Sera from eight B. caballi-infected equids, but none out of ten negative equid control sera, gave a positive signal in an rBcSBP4 based iELISA. Conclusions The Bcsbp4 gene is expressed in B. caballi blood stages. The BcSBP4 protein is a potential candidate for developing a novel serological test that could detect B. caballi infection in equids in tropical and subtropical countries worldwide.http://link.springer.com/article/10.1186/s13071-020-04241-9Equine piroplasmosisBabesia caballiiELISASBP4Serodiagnosis
spellingShingle Mona S. Mahmoud
Omnia M. Kandil
Nadia T. Abu El-Ezz
Seham H. M. Hendawy
Bassma S. M. Elsawy
Donald P. Knowles
Reginaldo G. Bastos
Lowell S. Kappmeyer
Jacob M. Laughery
Heba F. Alzan
Carlos E. Suarez
Identification and antigenicity of the Babesia caballi spherical body protein 4 (SBP4)
Parasites & Vectors
Equine piroplasmosis
Babesia caballi
iELISA
SBP4
Serodiagnosis
title Identification and antigenicity of the Babesia caballi spherical body protein 4 (SBP4)
title_full Identification and antigenicity of the Babesia caballi spherical body protein 4 (SBP4)
title_fullStr Identification and antigenicity of the Babesia caballi spherical body protein 4 (SBP4)
title_full_unstemmed Identification and antigenicity of the Babesia caballi spherical body protein 4 (SBP4)
title_short Identification and antigenicity of the Babesia caballi spherical body protein 4 (SBP4)
title_sort identification and antigenicity of the babesia caballi spherical body protein 4 sbp4
topic Equine piroplasmosis
Babesia caballi
iELISA
SBP4
Serodiagnosis
url http://link.springer.com/article/10.1186/s13071-020-04241-9
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