Wild Cervid Immunoparasitology: Methods and Development of Serological Assays for the Detection of Parelaphostrongylus tenuis

Parelaphostrongylus tenuis, or brain worm, is a neurotropic parasite affecting wild cervids across North America. In the definitive host, the white-tailed deer (Odocoileus virginianus), this parasite causes very little clinical disease. However, in atypical or aberrant hosts, significant neurological disease and mortality occurs. At present, the only means of diagnosis is post-mortem and requires a degree of technical skill to both recover and identify the parasite on necropsy and microscopic examination of neurological tissues. This project aimed to identify a novel immunogenic antigen of P. tenuis that could provide the bases for serological assays for the detection of this parasite. This would enable the antemortem detection of the parasite in atypical hosts such as moose (Alces alces) and elk (Cervus canadensis).

After immunogenic antigens were identified, investigation into specific epitopes using synthetic peptides was performed to maximize the specificity of the assay while maintaining a degree of acceptable sensitivity. The serological assay was then applied to populations of wild cervids in Pennsylvania, Minnesota, and Tennessee to detect the presence of P. tenuis antigens within their populations and compare these results to our current knowledge of parasite prevalence, risk factors of transmission, parasitic co-infections, and hematological parameters within these animals.

While the need for proper validation of this assay is still needed, our findings suggest that the methods of antigen selection employed to identify an immunogenic P. tenuis antigen have yielded promising results. Furthermore, the development of this serology, despite its limitations, appears to be detecting seropositive animals within the cervid populations. More research involving highly controlled live animal infections to determine true sensitivity and specificity, investigation into other identified antigens and epitopes, as well as investigation into cross reactivity with similar parasitic antigens is needed.