Live attenuated anticoccidial vaccines for chickens

Live attenuated anticoccidial vaccines have made a significant contribution to the control of chicken coccidiosis.The commercial live attenuated anticoccidial vaccines containing Eimeria parasites attenuated by serial passage in chicken embryos or by selection for precocity have limitations.The use of transgenic lines of Eimeria yielded promising results in vaccine research, and the feasibility of clustered regularly interspaced short palindromic repeats (CRISPR)-based genome editing in E. tenella has been reported.The advances in genetic manipulation on Eimeria parasites contribute to revolution of live attenuated anticoccidial vaccines, but there are several challenges. Chicken coccidiosis, caused by infection with single or multiple Eimeria species, results in significant economic losses to the global poultry industry. Over the past decades, considerable efforts have been made to generate attenuated Eimeria strains, and the use of live attenuated anticoccidial vaccines for disease prevention has achieved tremendous success. In this review, we evaluate the advantages and limitations of the methods of attenuation as well as attenuated Eimeria strains in a historical perspective. Also, we summarize the recent exciting research advances in transient/stable transfection systems and clustered regularly interspaced short palindromic repeats (CRISPR)-based genome editing developed for Eimeria parasites, and discuss trends and challenges of developing live attenuated anticoccidial vaccines based on transgenesis and genome editing. Chicken coccidiosis, caused by infection with single or multiple Eimeria species, results in significant economic losses to the global poultry industry. Over the past decades, considerable efforts have been made to generate attenuated Eimeria strains, and the use of live attenuated anticoccidial vaccines for disease prevention has achieved tremendous success. In this review, we evaluate the advantages and limitations of the methods of attenuation as well as attenuated Eimeria strains in a historical perspective. Also, we summarize the recent exciting research advances in transient/stable transfection systems and clustered regularly interspaced short palindromic repeats (CRISPR)-based genome editing developed for Eimeria parasites, and discuss trends and challenges of developing live attenuated anticoccidial vaccines based on transgenesis and genome editing.