Saffold Virus Exploits Integrin αVβ8 and Sulfated Glycosaminoglycans as Two Parallel Receptors for Infection

Saffold virus (SAFV), a member of the species Cardiovirus saffoldi within the Picornaviridae family, causes acute respiratory and gastrointestinal illnesses, as well as hand, foot, and mouth diseases. It is also suspected to be associated with neuronal disorders such as encephalitis and meningitis in severe cases. Despite its clinical significance, the virus-host interactions underlying SAFV pathogenicity remain largely unknown. Using a genome-wide CRISPR-Cas9 knockout screen, we identified receptors for SAFV infection: sulfated glycosaminoglycans (GAGs) and integrin aVb8. Single knockouts of SLC35B2 , an essential gene for sulfated GAG synthesis, or the integrin genes, ITGAV or ITGB8 partially reduced SAFV-3 susceptibility in HeLa cells, and double knockout conferred complete resistance. Furthermore, we demonstrated that SAFV-3 virions bind directly to sulfated GAGs and integrin aVb8. Based on these findings, we propose a model of SAFV infection, in which sulfated GAGs and integrin aVb8 function in parallel pathways during viral entry.