The Development of Genetic Modification Techniques in Intracellular Parasites and Potential Applications to Microsporidia

Microsporidia constitute a large phylum of eukaryotic obligate intracellular pathogens that can infect a variety of animal hosts. Understanding the biology of microsporidia is severely limited by our current inability to genetically manipulate these parasites. With a growing number of microsporidian genome sequences available and the revolution of successful CRISPR/Cas9 genome editing in virtually every organism tested, the development of DNA transformation techniques would likely lead to rapid and significant progress in understanding microsporidia biology. Here, we outline the challenges in transformation development and review the exciting recent development of DNA transformation and CRISPR/Cas9 genetic manipulation of Cryptosporidium, as well as summarize the successful genetic manipulation strategies in other intracellular eukaryotic parasites, including Plasmodium and Toxoplasma. By providing a list of possible strategies for transforming microsporidia, we hope to facilitate progress in this important area of microbiology and pathogenesis.