SUMO1 and infection: To confirm these results, 293T cells transiently overexpressing HA-SUMO1 and Ubc9 were infected with DKFJ/01, DKFJ/01-M1D30N, DKFJ/01-M1A215T, or DKFJ/01-M1D30N/A215T virus at a multiplicity of infection (MOI) of 1, and 10 h later, cell lysates were immunoprecipitated with anti-HA agarose.