Project description:Avian coccidiosis is a major disease of poultry caused by the intestinal protozoa Eimeria. Aviagen line A and line B birds show differential susceptibility to Eimeria infection, with line B birds exhibiting higher lesion scores and mortality. The objective of this study was to examine differential intestinal gene expression between line A and B chicks in response to a challenge with Eimeria maxima. Following challenge with 1 x 10^4 oocysts/chick, greater than 40% of line A chicks had lesion scores of 0 to 1 (on 0 to 4 scale), similar to controls. In contrast, all line B challenged chicks at this same dose had lesion scores of 2 to 4.
Project description:Apicomplexa parasite Eimeria is the causative agent of coccidiosis, which leads to enteritis in animals and causes huge economic burden to the farm industry. The Apicomplexan Apetala2/ERF (ApiAP2) transcription factors have proved to play key roles in various processes in other Apicomplexa parasites. However, little is known about the function of ApiAP2s in Eimeria species. In this study, we functionally characterized an ApiAP2 by direct knockout mediated by CRISPR-Cas9. Our results showed that the invasion efficiency, total oocyst output and virulence to the host were significantly impaired after EtAP2-S1 depletion. RNA-Seq and CUT&Tag analyze showed that EtAP2-S1 targets on the promoters of numerous genes and its knockout results in upregulation of 59 sag genes. Additionally, the knockout strain exhibits significantly reduced virulence but provides excellent immune protection, which makes it a good vaccine candidate. This study demonstrates that EtAP2-S1 is a fitness coffering gene that suppress the expression of sag genes in E. tenella, and this is the first practice in developing gene knockout vaccine for the control of coccidiosis.
Project description:BackgroundEimeria species are obligate intracellular apicomplexan parasites, causing great economic losses in the poultry industry. Currently wild-and attenuated- type anticoccidial vaccines are used to control coccidiosis. However, their use in fast growing broilers is limited by vaccination side effects caused by medium and/or low immunogenic Eimeria spp. There is, therefore, a need for a vaccine with high immunogenicity for broilers.MethodsThe avian yolk sac IgY Fc is the avian counterpart of the mammalian IgG Fc, which enhances immunogenicity of Fc-fusion proteins. Here, we developed a stable transgenic Eimeria mitis expressing IgY Fc (Emi.chFc) and investigated whether the avian IgY Fc fragment enhances the immunogenicity of E. mitis. Two-week-old broilers were immunized with either Emi.chFc or wild type Eimeria and challenged with wild type E. mitis to analyze the protective properties of transgenic Emi.chFc.ResultsChickens immunized with Emi.chFc had significantly lower oocyst output, in comparison with PBS, mock control (transgenic E. mitis expressing HA1 from H9N2 avian influenza virus) and wildtype E. mitis immunized groups after challenge, indicating that IgY Fc enhanced the immunogenicity of E. mitis.ConclusionsOur findings suggest that IgY Fc-expressing Eimeria may be a better coccidiosis vaccine, and transgenic Eimeria expressing Fc-fused exogenous antigens may be used as a novel vaccine-delivery vehicle against a wide variety of pathogens.