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Localization and immunogenicity of a low molecular weight antigen of Eimeria tenella
1Department of Pathobiology, Ontario Veterinary College, University of Guelph, Canada.
Insights
A low molecular weight antigen in Eimeria tenella was found throughout its life cycle. This antigen is immunogenic and may have a single dominant epitope, crucial for understanding avian coccidiosis.
Area of Science:
- Parasitology
- Immunology
- Veterinary Science
Background:
- Eimeria tenella causes significant economic losses in poultry farming.
- Understanding parasite antigens is key to developing effective vaccines and treatments.
- A specific low molecular weight (LMW) antigen recognized by monoclonal antibody C(3)4F(1) was previously identified.
Purpose of the Study:
- To localize the LMW antigen within the endogenous stages of Eimeria tenella.
- To assess the immunogenicity of this LMW antigen in chickens.
- To investigate the epitope characteristics of the LMW antigen.
Main Methods:
- Indirect fluorescent antibody assay and immunoelectron microscopy were used for antigen localization.
- Chicken serum antibody responses were measured using Western blots.
- Competitive antibody binding assays were performed to analyze epitope interactions.
Main Results:
- The LMW antigen was detected in sporozoites, meronts, gamonts, oocysts, and sporocysts of E. tenella.
- Antigen was present in parasite cytoplasm, pellicle, parasitophorous vacuole, and infected host cells.
- Chickens developed LMW antigen-specific antibodies as early as 4-6 days post-exposure.
- Monoclonal antibody C(3)4F(1) competed with chicken antibodies, indicating a single immunodominant epitope.
Conclusions:
- The LMW antigen is widely distributed throughout the endogenous life cycle of Eimeria tenella.
- This antigen is immunogenic in chickens, eliciting detectable antibody responses.
- The presence of a single, immunodominant epitope on the LMW antigen offers a potential target for diagnostic and control strategies against Eimeria tenella infections.
Abstract:
A low molecular weight (LMW) antigen recognized by a murine monoclonal antibody (C(3)4F(1)) was localized within endogenous stages of Eimeria tenella (USDA strain 80). Using indirect fluorescent antibody assay and immunoelectron microscopy, the LMW antigen was found in: sporozoites, first, second and third generation meronts, gamonts, unsporulated oocysts, and sporocysts. The antigen was observed in the cytoplasm and pellicle of the parasite, and in the parasitophorous vacuole, sporocyst walls and cytoplasm of infected host cells. The immunogenicity of this LMW antigen was assessed by antigen-specific serum antibody responses in chickens orally inoculated with live oocysts or injected intramuscularly with dead sporozoites. LMW antigen-specific serum antibodies were detected using Western blots of E. tenella sporozoites as early as 4 days after sporozoite injection and 6 days after oocyst inoculation. Unusually, the monoclonal antibody C(3)4F(1) reduced the binding of immune chicken serum to the antigen in a competitive antibody binding assay, but not the reverse, suggesting that there is a single, immunodominant epitope on this antigen.