FnCas12a/crRNA-Mediated Genome Editing in Eimeria tenella

Genetic manipulation for the non-model protozoan Eimeria: Advancements, challenges, and future perspective

Eimeria parasites pose a significant global threat to animal health, necessitating improved and cost-effective control measures. Genetic manipulation is pivotal for understanding Eimeria biology and designing targeted control strategies. Recent advancements, including genome sequencing and the development of transient and stable transfection systems, have significantly enhanced insights into the molecular biology of Eimeria. These advancements have paved the way for cutting-edge techniques like CRISPR-Cas9 gene editing. This review summarizes the key milestones in the development of genetic manipulation platforms for Eimeria and their transformative applications, such as the development of next-generation drugs, vaccines, and Eimeria-based vaccine vectors. Furthermore, this review provides insights that could be applicable to the establishment of genetic tools for other protozoan organisms.

Innovative prevention and control of coccidiosis: targeting sporogony for new control agent development

Coccidiosis is one of the most significant diseases affecting the poultry industry, with recent estimates indicating that it causes annual losses exceeding £10 billion globally. Increasing concerns over drug residues and resistance have elevated the importance of safe and effective vaccines as the primary method for controlling coccidiosis and other animal diseases. However, current commercial live vaccines for coccidiosis can negatively impact the feed conversion rates of young broilers and induce subclinical symptoms of coccidiosis, limiting their widespread adoption. Eimeria species, the causative agents of coccidiosis, exhibit unique biological characteristics. Their life cycle involves 2 or more generations of schizogony and 1 generation of gametogony within the host, followed by sporogony in a suitable external environment. Sporogony is crucial for Eimeria oocysts to become infectious and propagate within the host. Focusing on the sporogony process of Eimeria presents a promising approach to overcoming technical challenges in the efficient control of coccidiosis, addressing the urgent need for sustainable and healthy farming practices. This paper systematically reviews existing control strategies for coccidiosis, identifies current challenges, and emphasizes the research progress and future directions in developing control agents targeting sporogony. The goal is to provide guidance for the formulation of scientific prevention and control measures for coccidiosis.

Genome Editing in Apicomplexan Parasites: Current Status, Challenges, and Future Possibilities

Clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated protein (Cas) technology has revolutionized genome editing across various biological systems, including the Apicomplexa phylum. This review describes the status, challenges, and applications of CRISPR-Cas9 editing technology in apicomplexan parasites, such as Plasmodium, Toxoplasma, Theileria, Babesia, and Cryptosporidium. The discussion encompasses successfully implemented CRISPR-Cas9-based techniques in these parasites, highlighting the achieved milestones, from precise gene modifications to genome-wide screening. In addition, the review addresses the challenges hampering efficient genome editing, including the parasites' complex life cycles, multiple intracellular stages, and the lack of robust genetic tools. It further explores the ethical and policy considerations surrounding genome editing and the future perspectives of CRISPR-Cas applications in apicomplexan parasites.

CRISPR-Cas9-based method for isolating microgametes of Eimeria tenella

Eimeria tenella infections are known to cause severe caecal damage and death of the infected chicken. Gamogony is an essential stage in E. tenella life cycle and in the establishment of coccidiosis. Prior research had extensively explored isolation and separation of the parasite gametes - microgamete (male) and macrogamete (female). However, there is little information on the efficient, highly purified and distinctly separated male and female gametes. In this study, we generated a genome editing line expressing mCherry fluorescent protein fused with GCS1 protein in E. tenella by using Toxoplasma gondii CRISPR-Cas9 system, flow cytometry and fluorescence microscopy. This allowed precise separation of E. tenella male and female gametes in the transgenic parasite population. The separation of male and female gametes would not only build on our understanding of E. tenella transmission, but it would also facilitate development of gametocidal compounds as drug targets for E. tenella infection.

Live attenuated anticoccidial vaccines for chickens

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.

RPA assay coupled with CRISPR/Cas12a system for the detection of seven Eimeria species in chicken fecal samples

Chicken coccidiosis is one of the most common and economically important diseases in the global poultry industry, and it is caused by at least one of the seven Eimeria species. A simple and reliable way to distinguish Eimeria species in infected chicken is critical for the surveillance, control, and eradication of chicken coccidiosis. In this study, a recombinase polymerase amplification (RPA) assay coupled with the clustered regularly interspaced short palindromic repeats (CRISPR)/Cas12a system (RPA-CRISPR/Cas12a) was developed for the detection of Eimeria species in chicken fecal samples. This assay is highly specific to the seven Eimeria species and it does not cross react between species. Assessment of analytical sensitivity revealed that a single copy of plasmid DNA could be detected. Comparative analysis revealed strong agreement between RPA-CRISPR/Cas12a assays and real-time qPCR to reliably detect all seven Eimeria species in fecal chicken samples. Importantly, the cleavage products could be visualized under a blue light instrument, making it possible for the rapid detection of Eimeria species for on-site testing. Collectively, our study demonstrated that RPA-CRISPR/Cas12a assays offer a simple and reliable diagnostic method for Eimeria species.