Identification of diagnostic antigens for South American Babesia caballi infections.

This research article explores the identification of distinctive antigens in the South American variant of Babesia caballi – a parasite known to infect horses, using diagnostic tests including ELISA, IFAT and Western blot. Their findings show that 48 kDa and 50 kDa antigens are recognized early in infected horses and could be potential diagnostic markers for the disease.

Study Methodology

• The research involved the study of 60 horses from a breeding herd in Brazil. Blood samples were taken regularly and tested using the Enzyme-Linked Immunosorbent Assay (ELISA), the Immunofluorescence Antibody Test (IFAT) and Western blot.
• All foals (young horses) started with maternal antibodies that were detectable by ELISA and IFAT, indicating a natural immunity passed from mother horse to foal.
• The researchers observed an onset of sero-conversion, which is the time period during which a specific antibody develops and becomes detectable in the blood, between the 2nd and 5th month of age in foals.

Antigen Recognition and Sero-Conversion

• In the process of infection, the antigens with molecular masses of 48 and 50 kDa were recognized first. An antigen is a toxin or other foreign substance that induces an immune response in the body, especially the production of antibodies.
• Out of 79 sera taken after sero-conversion, an astonishing 78 reacted with the 48 kDa antigen, while 76 reacted with the 50 kDa antigen. Fewer sera reacted with the 70, 112, and 141 kDa antigens, implying that the 48kDa and 50kDa antigens were the most reactive.
• It was observed that sera from horses older than 1 year reacted with all 5 diagnostic antigen bands, but in those older than 3 years, the reaction was noticeably weaker.

Diagnostic Application and Potential

• The 48 and 50 kDa antigens seemed to be conserved across all strains of B. caballi examined so far and are consistently recognized by all infected horses, implying their great diagnostic potential.
• B. caballi antigens of these molecular weights have the potential to serve as the target antigens for a serological test based on antigens produced by recombinant DNA techniques. This infers that a diagnostic test could be developed that targets these specific antigens, potentially increasing the accuracy and efficacy of B. caballi infection detection.