Propagation of human sapovirus GII.7 strain in HuTu80 subcloned cells

Human sapoviruses (HuSaVs), which cause acute diarrhea worldwide, are genetically diverse and divided into four genogroups (GI, GII, GIV, and GV). These were further subdivided into 18 genotypes (GI.1-7, GII.1-8, GIV.1, GV.1, and -2). Among them, only one strain has been reported worldwide for GII.7 to date. This strain was detected during a fecal pathogen screening of outpatients with gastroenteritis in Kumamoto Prefecture, Japan in 2008. We established a virus stock panel of diverse HuSaV strains as bioresources for further virological characterization studies and successfully propagated multiple HuSaV strains using a human duodenum cell line, HuTu80, supplemented with conjugated bile acids. However, several HuSaV genotypes including GII.7 strain did not propagate under the tested conditions. This study reports the successful propagation of the HuSaV GII.7 strain in HuTu80 subcloned cells. The propagated virus is an additional bioresource. We further used scaled-up serially passaged progeny viruses as antigens for antiserum production and demonstrated differences in immunogenicity among the cell culture-propagated HuSaV GII strains.