Along with others, we have shown that respiratory infections with HBoV elicit B-cell immune responses (11) (12) (13) (14) (15) and can be diagnosed serologically by using prokaryotic virus protein 2 (VP2) antigens in immunoblots (11) . We report production in insect cells of VP2 of virus-like particles (VLPs) and their use in enzyme immunoassays (EIAs) for detection of HBoV-specific immunoglobulin (Ig) M and IgG in paired serum samples of pediatric patients with acute wheezing and in single serum samples of young healthy adults. Serologic results were compared with those of HBoV quantitative PCR (qPCR) of nasopharyngeal aspirates (NPAs) and paired serum samples of 258 children with complete sample sets. Clinical signs and symptoms of wheezing children with serologically verified acute HBoV infections with or without other respiratory virus infections (15 other viruses studied [10] ) were compared with those of children infected with respiratory syncytial virus (RSV) or rhinovirus.