Rapid and specific serodiagnosis of western equine encephalitis virus infection in horses.

The research examines the efficacy of using enzyme immunoassay to detect the presence of western equine encephalitis (WEE) virus in horses, by detecting specific immunoglobulin responses. This method proved successful, especially when diagnosing rapidly as antibodies to the virus were promptly found in the horses’ blood.

Study Design and Procedure

• The research study focused on testing paired sera—from 28 non-vaccinated horses presenting with the WEE virus—using enzyme immunoassay.
• This assay detected the presence of Immunoglobulin M (IgM) and Immunoglobulin G (IgG)—types of antibodies produced by the immune system in response to an infection.

Findings

• 21 out of the 28 horses experienced significant increases or decreases in serum IgM levels. This change in IgM levels is indicative of the presence of the WEE virus, confirming these horses’ diagnosis.
• Of the remaining seven horses, the study states one had stable IgM levels, one had a minimal increase, two showed decreases, and three did not have enough samples for thorough testing.
• Upon testing 56 blood samples taken from the 28 horses, it was found that 29 samples had been collected within the first three days of symptoms. Every horse and 48 out of 53 available serum samples contained IgM antibodies specific to the WEE virus.
• Furthermore, 27 of 45 other horses—showing symptoms of WEE but yet to be vaccinated—also tested positive for IgM in their serum samples.
• Notably, the IgM present did not show cross-reactivity with the eastern equine encephalitis virus, demonstrating the specificity of the response to the WEE virus.

Conclusion

• The results suggest that detecting the presence of the WEE virus using enzyme immunoassay proves effective. The prompt emergence and lack of persistence of IgM antibodies, coupled with their specificity to the WEE virus, make this method a convenient tool for rapid diagnosis.