Atomic structure of human sapovirus capsid by single particle cryo-electron microscopy

Summary Sapovirus is a cause of acute gastroenteritis in humans and animals. Infants and younger children have the greatest disease burden. Although it shares many similarities with norovirus, the lack of detailed structural information has hampered the development of vaccines and therapeutics. Here, we investigated the human sapovirus VLP by single particle cryo-electron microscopy and are the first to report the atomic structure of the capsid at 2.9 Å resolution. The atomic model revealed the domain interactions of the capsid protein and functionally important amino acid residues. The extended loop from the P1 subdomain was involved in interactions in the P2 domain, forming unique arch-like dimeric protrusions of capsid proteins. All hypervariable regions that are important candidates for immune response or receptor binding, formed a large cluster at the top of the P domain. These results pave the way for developing vaccines, antiviral drugs, and diagnostic systems for this infectious disease.