Our results from the cELISA are lower than those previously reported for HBoV1 in adults and children [18, 19, 32] , where HBoV1 antibodies against HBoV1 VP2 were detected by ELISA. Hence, the seroprevalence of HBoVs may be overestimated due to the serological cross-reactivity among the four HBoV species in previous studies. However, according to our cELISA results, the seroprevalence of HBoV1-3 in Beijing adults is somewhat higher than that reported in Finnish and Pakistani adults [22] . This disparity may be attributed to the difference of geographical location [22] .