Immunoglobulin M-capture enzyme-linked immunosorbent assay testing of cerebrospinal fluid and serum from horses exposed to west nile virus by vaccination or natural infection.

The research study focuses on the detection of West Nile (WN) virus in horses through the testing of cerebrospinal fluid (CSF) and serum. The study particularly aimed to study the blood-brain barrier in horses infected with the WN virus, compare testing in serum and CSF, and describe the IgM response in both the serum and CSF of vaccinated horses.

Research Methods

• The study was conducted on horses naturally exposed to the West Nile Virus either by vaccination or natural infection.
• CSF was collected from two different sites: the lumbosacral (LS) space and the allanto-occipital (AO) space in a total of 27 horses.
• To evaluate the blood-brain barrier (BBB) in horses infected with WN virus, they calculated the albumin quotient (AQ) and IgG index which provide a way to measure the function of the BBB.
• The IgM-capture-enzyme-linked immunosorbent assay (MAC-ELISA) was employed. This method is used to detect antibodies in serum and CSF that were produced in response to the WN virus infection.

Research Findings

• CSF collected from the LS site showed a higher IgG index compared to the AO site, indicating that the collection site might potentially influence the results. However, the mean AQ, irrespective of the collection site, did not exceed reference values.
• There was a 100% match between results of CSF and serum testing for IgM by the MAC-ELISA testing, signifying that the method is reliable for detection of anti-WN virus IgM in both serum and CSF.
• A notable finding was that the positive to negative antigen ratios were higher (34.5) in CSF compared to serum (8.5), indicating the lower nonspecific reactivity in CSF samples.
• Horses vaccinated against the WN virus did not develop an IgM response at 1:400 mg/dL in serum. However, some horses developed a weak IgM response in serum but not in CSF.
• The research concluded that the integrity of the BBB in horses infected with the West Nile virus was normal, suggesting the virus does not significantly compromise the barrier’s function.

Conclusion

This research is significant as it gives insight into the immune response of horses to the West Nile virus. The findings contribute valuable information to furthering the understanding of the efficacy of IgM-capture enzyme-linked immunosorbent assay (MAC-ELISA) in detecting WN virus infections in horses. The implications of these findings could potentially be used for improving diagnosis, prevention, and action against the West Nile virus in veterinary medicine.