Humoral immune response against human bocavirus VP2 virus-like particles.

Human bocavirus (HBoV) was recently detected in samples from children and infants with infections of the respiratory tract. Here we analyze the prevalence of IgG and IgM antibodies against HBoV virus-like VP2 particles in healthy adult blood donors and children using a newly established standardized enzyme-linked immunosorbent assay. Virus-specific IgG antibodies were frequently detected in infants with active viremia and respiratory illness (10/24, 42%) and in young children without detectable HBoV genomes in their blood (27/52, 52%). In sera obtained from healthy adults, ubiquitous VP2-specific antibodies were found in 280/299 (94%) cases. HBoV-specific IgM antibodies were detected in 10/24 (42%) of sera samples obtained from HBoV DNA-positive children, and in 6/24 (25%) the sera displayed equivocal responses. In contrast, VP2-specific IgM was not detectable in samples obtained from 52 children without detectable amounts of HBoV genomes in their blood. Only 2/299 sera samples from healthy adult blood donors were found to be IgM-positive (1%), and equivocal IgM responses were observed in 9/299 (3%) individuals. In conclusion, a high IgG seroprevalence of HBoV in the adult population was observed, whereas the presence of virus-specific IgM was associated with viremia. These data show that ELISA test systems for the detection of HBoV-specific antibodies are a valuable tool for serological diagnosis of this new emerging pathogen.