This document summarizes research on the human astrovirus 1 capsid acidic domain. Key findings include: 1) The domain was successfully cloned, expressed, and purified in E. coli. 2) Computational tools predicted an unstructured N-terminal region and four C-terminal helices, supported by NMR and CD. 3) Limited proteolysis isolated the helical region but crystallization attempts were unsuccessful. 4) Future work involves expressing just the helical regions to pursue crystallization or NMR structure determination.