Engineering host-determinants of novel gut Microviruses PROJECT SUMMARY Non-phiX-like Microviruses are small, single-stranded DNA viruses that are numerous, diverse, and poorly understood members of the human gut virome. Their simple genetic structure makes them amendable to manipulation of their host specificity, while their small size enables phage production via de novo synthesis of their genomes from in-silico data, followed by transformation of virus-generating DNA in the host. The Research Project Leader (RPL) has previously established a strong research program to study these elusive phages. Through investigation of their biology and ecological roles in microbiomes, he is poised to develop microviruses as a versatile tool for the targeted manipulation of the gut microbial community towards desired health outcomes such as staving off bacterial infections. Several obstacles must be overcome before practical applications of his research can be explored through R01 grant funding. The patterns and determinants of microviral host identity and specificity need to be understood, and the feasibility of re-introducing engineered phages into mixed microbial populations needs to be demonstrated. This proposal addresses these issues through three scientific aims: 1) Identifying natural hosts and establishing virus-host systems for major microvirus lineages of the human gut, 2) Establishing a system for targeted modulation of Microviridae host range, and 3) Re-introducing phages into controlled microbiomes for precise manipulation of microbial community composition. Success in these endeavors requires extensive experience in culturing and manipulating not only microviruses (the RPL’s expertise), but also with anaerobic hosts such as Bacteroides and Prevotella. Through the Oklahoma Center for Microbiome Research (OCMR) Anaerobic Microbiology Core and COBRE-facilitated mentorship by experts in virology, metagenomics, and biology of human gut microbes, as well as interactions with a wide range of researchers in the microbiome field, the RPL will have access to the technical infrastructure, intellectual expertise, and professional network needed to pursue these aims. The project is hence crucial to the RPL’s short and long-term career goals of attaining research independence in the form of an R01/R35 grant; establishing his laboratory as a leading institution in the research of microviruses; and developing microviruses as modular tools for a fully synthetic phage therapy platform.