Abstract: In this study, we designed novel truncated Babesia caballi (B. caballi) recombinant proteins from the previously used B. caballi proteins; 134-Kilodalton Protein (rBC134) and Merozoite Rhoptry 48 Protein (rBC48). Then, we evaluated the diagnostic performance of the newly designed proteins when used as a single antigen or when used as cocktail antigen consists of rBC134 full length (rBC134f) + newly designed rBC48 (rBC48t) or newly designed rBC134 (rBC134t) + rBC48t for the detection of B. caballi infection in horse using indirect enzyme-linked immunosorbent assay (iELISA). We used one dose and a half of each antigen in the cocktail formulas. The serum samples were collected from different endemic areas in addition to the sera collected from horses experimentally infected with B. caballi were used in the present study. Cocktail antigen in full dose of (rBC134f + rBC48t) exhibited the highest optical density (OD) values with B. caballi-infected sera and showed the lowest OD values with normal equine sera or B. caballi, and Theileria equi mixed infected sera in comparison with the single antigen. Interestingly, the same cocktail antigen exhibited the highest concordance rate (76.74%) and kappa value (0.79) in the screening of 200 field serum samples collected from five B. caballi endemic countries, including South Africa (n = 40), Ghana (n = 40), Mongolia (n = 40), Thailand (n = 40), and China (n = 40) using iELISA and the results were compared to those of indirect fluorescent antibody test (IFAT) as a reference. Moreover, the identified promising cocktail full dose antigen (rBC134f + rBC48t) showed that it can detect the infection as early as the 4th day post-infection in sera collected from experimentally infected horses. The obtained results revealed the reliability of the rBC134f + rBC48t cocktail antigen when used in full dose for the detection of specific antibodies to B. caballi in horses which will be useful for epidemiological surveys and control of equine babesiosis.
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The research paper discusses the design of new truncated recombinant proteins to help in the detection of Babesia caballi infection in horses using an indirect enzyme-linked immunosorbent assay (iELISA), with promising results derived from a ‘cocktail antigen’ combination of proteins.
Methods:
The researchers have used previously studied proteins from Babesia caballi (B. caballi) – 134-Kilodalton Protein (rBC134) and Merozoite Rhoptry 48 Protein (rBC48) – to design novel truncated versions.
Once the new proteins were designed, their diagnostic performance was evaluated. The proteins were used either individually or as part of a ‘cocktail antigen’ which comprised full-length rBC134 (rBC134f) and the newly designed rBC48 (rBC48t), or the newly designed rBC134 (rBC134t) and rBC48t.
Each antigen in the cocktail was used at ‘one and a half dose’.
Serum samples collected from different endemic areas as well as from horses experimentally infected with B. caballi were used in the study.
Results:
The findings revealed that the cocktail antigen comprising the full dose of rBC134f and rBC48t produced the highest optical density (OD) values and most reliable results with B. caballi-infected sera. Its performance was superior to using the single antigen.
Notably, the same cocktail antigen showed a high rate of concordance (76.74%) and kappa value (an index that compares observed accuracy with expected accuracy, 0.79 in this case) in field serum sample screening from five B. caballi endemic countries: South Africa, Ghana, Mongolia, Thailand, and China.
The promising cocktail full dose antigen (rBC134f + rBC48t) was also able to detect an infection as early as four days post-infection, in serum collected from horses experimentally infected.
Conclusion:
The results demonstrate the efficacy of the cocktail antigen comprising rBC134f and rBC48t in the full dose for detecting specific antibodies to B. caballi in horses, thereby offering a promising tool for conducting epidemiological surveys and controlling equine babesiosis.
Cite This Article
APA
El-Sayed SAE, Rizk MA, Baghdadi HB, Ringo AE, Sambuu G, Nugraha AB, Igarashi I.
(2023).
Development of a promising antigenic cocktail for the global detection of Babesia caballi in horse by ELISA.
PLoS One, 18(4), e0284535.
https://doi.org/10.1371/journal.pone.0284535
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