Evaluation of new leptospiral antigens for the diagnosis of equine leptospirosis: An approach using pan-genomic analysis, reverse vaccinology and antigenic selection.

The researchers in this article aim to find new leptospiral antigens capable of enhancing the process of diagnosing equine leptospirosis, a disease in horses resulting from leptospiral bacteria. They use a variety of methods, including reverse vaccinology, to predict and select the best antigens that can make tests more accurate and efficient compared to the current diagnostic method, the microscopic agglutination test (MAT).

Methods

• The researchers use a variety of methods such as reverse vaccinology (RV) and antigenic selection to predict and select the best leptospiral targets that can be used to improve the process of diagnosing equine leptospirosis.
• They run an antigenic selection based on parameters such as proteins with an antigenicity score equal to or greater than 0.5, at least one B cell epitope, and protein size between 10 and 275 KDa.
• The researchers clone and express new leptospiral proteins, and they screen these against horse sera on a single analysis and comparative combinations.
• They calculate the sensitivity, specificity, accuracy, positive predictive value (PPV), and negative predictive value (NPV) of these potential new diagnostic reagents.

Limitations

• The researchers acknowledge several limitations in their study. These include (a) limitations with the horse sera used in the tests; (b) overreliance on MAT results, and (c) limitations with the serovar and species strains used in the analysis.
• Among these limitations, the researchers mention that the horse sera used in the tests were limited to those submitted to the Animal Health Diagnosis Center, and these were only tested against seven serovars.
• They also admit that the highest titre MAT results were considered to be the infecting serovar, which may not always be the case.
• Finally, they mention the limitations related to the representation of the serovars and the limited variety of serovars and species included in the genetic analysis.

Conclusion

• The researchers suggest that the new leptospiral antigens identified through their research could enhance the sensitivity and specificity of ELISA for detecting leptospirosis in horses.
• They propose that these new antigens could support the detection of leptospirosis in horses, particularly when used in combination with clinical signs.
• According to the researchers, some of these antigens might be used to enhance the detection of the infecting serovar, thus contributing to improved diagnosis of equine leptospirosis.