Development of ELISA test for determination of the level of antibodies against Rhodococcus equi in equine serum and colostrum.

This research aimed to develop a standardized ELISA test to determine the level of antibodies against Rhodococcus equi present in equine serum and colostrum. The test was effective in detecting these antibodies, proving particularly useful for assessing the efficacy of vaccinations.

Background of the Study

• The research focused on Rhodococcus equi infection, which is a key cause of mortality in foals within the first six months of life. It is a global issue, posing serious threats to equine health.
• The use of serological tests in diagnosing rhodococcosis is not widespread, but they are vital to immunological studies. This research aims to develop and standardize an ELISA test to specifically determine the level of antibodies against Rhodococcus equi in equine serum and colostrum.

Methodology

• The researchers used bacterial cell lysate as the antigen for the ELISA test.
• The test was standardized using 175 serum samples from adult horses, sourced from both rhodococcosis-free farms and farms where the infection was endemic.
• Positive and negative control sera were also used to ensure the test’s effectiveness.
• The test was primarily designed to detect IgG antibodies against VapA protein, and its validity was confirmed through Western blot analysis.

Results and Findings

• The developed ELISA test showed low well-to-well variation and did not necessitate inactivation of the sera, making it practical and easy to perform.
• The antigen-coated ELISA plates had a shelf life of 21 days.
• The test demonstrated a significant increase of R. equi-specific antibodies in both serum and colostrum in response to vaccination.
• No remarkable difference was observed in the baseline antibody level in adult horses sourced from both rhodococcosis-free and endemic farms. The finding implies that the presence of R. equi infection does not necessarily influence the baseline antibody level in adult horses.

Implication of the Study

• This research contributes to the development of an ELISA test that can effectively detect Rhodococcus equi antibodies in equine serum and colostrum.
• This developed test has useful future applications in evaluating vaccine efficacy against Rhodococcus equi. Therefore, it is an effective tool in immunological studies concerning this particular equine infection.