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High pathogenicity and strong immunogenicity of a Chinese isolate of Eimeria magna Pérard, 1925
Geru Tao1, Yunzhou Wang1, Chao Li1
1Key Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China; National Animal Protozoa Laboratory, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China.
Abstract:
Coccidia infection of rabbits with one or several species of parasites of the genus Eimeria causes coccidiosis, a disease leading to huge economic losses in the rabbit industry. Eimeria magna, one of the causal agents of rabbit coccidiosis, was characterized as mildly pathogenic and moderately immunogenic in previous studies. In this study, we identified a Chinese isolate of E. magna by testing its biological features (oocyst morphology and size, prepatent time) and sequencing its internal transcribed spacer 1 (ITS-1) DNA fragment. This isolate is highly pathogenic; infection of rabbits with only 1×102 oocysts caused a 55% reduction in weight gain in 14days. In addition, immunization with 1×102 oocysts prevented body weight loss against re-infection with 5×104 oocysts, indicating the high immunogenicity of this isolate. Our study described the distinctive phenotype of the Chinese isolate of E. magna and contributed to the research of geographic variation of rabbit coccidia.
Insights
A new Chinese isolate of Eimeria magna, a parasite causing rabbit coccidiosis, is highly pathogenic and immunogenic. This finding is crucial for understanding geographic variations in rabbit coccidia and managing the disease in the rabbit industry.
Area of Science:
- Veterinary Parasitology
- Animal Science
- Molecular Biology
Background:
- Coccidiosis, caused by Eimeria species, results in significant economic losses in rabbit farming.
- Eimeria magna is a known rabbit coccidia species, previously considered mildly pathogenic and moderately immunogenic.
Purpose of the Study:
- To characterize a novel Chinese isolate of Eimeria magna.
- To assess the pathogenicity and immunogenicity of this specific isolate.
- To investigate geographic variations in rabbit coccidia.
Main Methods:
- Biological characterization including oocyst morphology, size, and prepatent time.
- Molecular identification using sequencing of the internal transcribed spacer 1 (ITS-1) DNA fragment.
- Experimental infection and re-infection studies in rabbits to evaluate pathogenicity and immunogenicity.
Main Results:
- The Chinese Eimeria magna isolate demonstrated high pathogenicity, causing a 55% reduction in weight gain with only 1x10^2 oocysts.
- Immunization with 1x10^2 oocysts conferred protection against a high challenge dose (5x10^4 oocysts), indicating strong immunogenicity.
- Distinctive biological features and high pathogenicity/immunogenicity were identified in this Chinese isolate.
Conclusions:
- The Chinese isolate of Eimeria magna presents a significantly different phenotype compared to previously studied isolates.
- This isolate's high pathogenicity and immunogenicity have important implications for coccidiosis control strategies in rabbits.
- The study highlights the importance of considering geographic variations in Eimeria species for effective disease management.