Use of recombinant calflagin protein as a potential candidate for diagnosis of Trypanosoma evansi infection.

This research investigates the use of a protein called calflagin as a candidate for diagnosing infection of surra, a disease caused by the parasite Trypanosoma evansi, in animals like horses. The study cloned, expressed, and evaluated the protein’s potential as a diagnostic tool, and found that it might be an efficient marker for the disease, even detecting it from an early stage of infection.

Investigating Alternatives to Native Antigens

• This research was driven by the need for more efficient methods of diagnosing surra, a disease caused by Trypanosoma evansi, which currently relies on using native antigens from T. evansi grown in rodents.
• The team aimed to find a better diagnostic candidate that could serve as an alternative, so they focused on a protein called 26 kDa calflagin which has 218 amino acids, and was sourced from T. evansi in an Indian strain.

Cloning, Expressing, and Testing Calflagin

• Calflagin was cloned and then expressed in Escherichia coli, a type of bacteria often used in research for the expression of recombinant proteins.
• The potential of the recombinant calflagin (rCLF) as a diagnostic antigen was then tested on serum samples from horses infected with T. evansi, using immunoblot and indirect ELISA procedures.
• The results showed that it could detect antibodies against T. evansi, as early as 10 days and 14 days post-infection using immunoblot and ELISA respectively.

Evaluating Cross-Reactivity and Localization of the Protein

• The rCLF antigen was evaluated for cross-reactivity with serum samples of horses that were already positive for other infections: Equine herpesvirus 1, Burkholderia mallei, and Theileria equi. There was no evidence of cross-reactivity, meaning the rCLF only recognized T. evansi antibodies, and not the antibodies against the other diseases.
• The native immunogenic protein was found to be located near the flagellum attachment, based on indirect immunofluorescence antibody tests with anti-CLF rabbit hyperimmune serum.

Potential Use of rCLF Protein for Diagnosing Surra

• The results showed that the rCLF protein could distinguish between T. evansi-positive and -negative serum samples in horses, thus it could potentially be used for serological surveys in animals for surra.
• Moreover, rCLF could be used with other potential diagnostic candidates to enhance diagnostic efficiency, showing promise for the early diagnosis and management of surra.