A survey for antibodies to equine arteritis virus in donkeys, mules and zebra using virus neutralisation (VN) and enzyme linked immunosorbent assay (ELISA).

This study involves a comprehensive survey to detect equine arteritis virus (EAV) antibodies in donkeys, mules, and zebras using two different methods. The researchers found a wide distribution and increasing prevalence of EAV antibodies among donkeys in South Africa, suggesting exposure to the same virus strain found in horses. However, no EAV seropositive zebras were detected.

Background and Methodology of Research

• The authors of the research conducted a seroepidemiological survey on 4300 donkeys in South Africa to investigate the presence of antibodies related to equine arteritis virus (EAV). The presence of these antibodies would suggest that the donkeys have been previously exposed to this virus.
• The study employed two testing methods: virus neutralisation (VN) and enzyme-linked immunosorbent assay (ELISA).
  • VN tests are used to measure the ability of the donkey sera to inhibit equine arteritis virus infection, which indicates the presence of EAV antibodies in the donkeys’ blood.
  • ELISA tests are used to detect the antigen-antibody reaction. In this study, the ELISA test specifically bound to a recombinant antigen derived from the Bucyrus isolate of EAV.

Results and Discussion

• The study found that there was a good correlation between EAV neutralizing antibody titres and ELISA absorbance values (0.8631). This suggests that the results from these two testing methods were generally consistent.
• The ELISA was sensitive and specific (99.2% and 80.3% respectively) for donkey sera when compared to the VN test. The recombinant ELISA antigen, derived from a strain of EAV, did not cross-react with sera positive for common African equine pathogens, which indicates that the detection of EAV is likely accurate and not due to other equine diseases.
• Donkeys in Morocco and Zimbabwe were also found to test positive on both VN and ELISA tests, suggesting the presence of EAV in these regions. Moreover, seropositive mules were found in South Africa and Morocco, indicating that mules are also naturally infected with EAV.
• No seropositive zebras were found among the 266 tested from game reserves or zoos in 9 different countries, suggesting that zebras may not be naturally susceptible to EAV or have not been exposed to the virus.

Implications of the Research

• The results confirm that in addition to horses and donkeys, mules can also be naturally infected with EAV. This opens up a need for further research to understand the implications and effects of EAV on mules.
• The absence of EAV seropositive zebras urges researchers to investigate why the virus does not seem to affect this species, which could be beneficial for understanding the virus and working towards a vaccine.
• The widespread distribution and increasing prevalence of EAV in donkeys denote that public health regulations and guidelines may need adjustment to prevent and manage the spread of this virus.