Development and Use of an Enzyme-Linked Immunosorbent Assay to Determine Temporal Exposure Patterns to Putative Agents of Nocardioform Placentitis.

The research paper discusses the development of an enzyme-linked immunosorbent assay (ELISA) to quantify antibodies against bacteria Crossiella equi and Amycolatopsis spp., which are associated with a disease known as nocardioform placentitis in horses. The developed ELISA was then used to understand the temporal exposure patterns to these bacteria, aiding in a greater understanding of the disease’s epidemiology.

Overview of the Study

• The researchers focused on nocardioform placentitis, an infectious disease in horses which can lead to late-term abortion, premature births, or the birth of underdeveloped foals. The disease is sporadic and most commonly associated with two types of bacterial infection – Crossiella equi and Amycolatopsis spp.
• The primary goal of the study was to create an enzyme-linked immunosorbent assay (ELISA) that could measure antibodies against these two bacteria. By doing so, they planned to use the ELISA to determine when horses’ exposure to these bacteria happens.

Development of ELISA

• To develop the ELISA, the research team gathered serum samples from infected and non-infected mares during the 2020 foaling season. They used 8 samples from mares infected with Crossiella equi, 32 from mares infected with Amycolatopsis spp., and 51 from non-infected mares.
• These samples were then used to develop and perfect the ELISA that were specific to each bacterium.

Application of ELISA and Result Analysis

• Following the ELISAs’ development, serum samples from mares at a central Kentucky Thoroughbred farm, collected over two different periods, were examined. A one-way analysis of variance (ANOVA) was used to understand the differences between various groups.
• The results showed that mares infected with Crossiella equi had significantly higher ELISA unit (EU) values for the Crossiella equi ELISA near parturition, compared to other groups. This supports that this ELISA could identify Crossiella equi exposure.
• In contrast, EU values from Amycolatopsis spp. ELISA were not significantly different between infected and non-infected mares, suggesting that this ELISA may not be specific to Amycolatopsis spp.

Insight into the Timing of Bacterial Exposure

• During 2013-2014, EU values for the Crossiella equi ELISA improved significantly from June to late September, suggesting exposure to this bacterium could happen during summer and fall months.
• This discovery might aid in a comprehensive understanding of nocardioform placentitis’s epidemiology, guide the development of an effective experimental model, and allow for further refinement of these ELISAs.