Project Summary Virus-based technology has emerged as a powerful tool in neuroscience and vision research, enabling optogenetic and chemogenetic manipulation of brain activity, circuit tracing, and gain- and loss-of-function genetic modifications in the retina and brain. Electrophysiology- and imaging-focused laboratories, however, often lack the expertise and resources needed to effectively employ these molecular biology approaches, and standardized methods can enhance the productivity of even experienced molecular neuroscience groups. The Viral Module was created to fill this need by generating, maintaining, and designing high-quality viruses for vision applications. Led by Dr. Zhigang He, and a staff of experienced molecular biologists, the Viral module will serve as a repository for the proper storage, maintenance, handling, and distribution of pre-made viral vectors and also assist in the design, optimization, and generation of custom viral constructs. Despite its recent addition to the Vision Core, the Viral Module has already been utilized by a significant number of investigators working in both rodents and primates and constitutes an essential resource for the wider Harvard vision research community.