title: CD4+ T helper cell responses against human bocavirus viral protein 2 viruslike particles in healthy adults.
abstract: BACKGROUND
  Human bocavirus (HBoV) was recently described as a new member of the Parvoviridae family, and its possible association with respiratory illness in infants has been discussed. To date, HBoV genomes have been detected worldwide in respiratory tract samples obtained from children with pulmonary diseases, whereas only limited data on virus-specific immunity are available, mainly because of the lack of recombinant viral antigens.
  
  
  METHODS
  HBoV viruslike particles (VLPs) were produced in insect cells and characterized by electron microscopy and cesium chloride gradient centrifugation. HBoV viral protein 2 (VP2)-specific antibodies and CD4+ T helper cell responses were analyzed by enzyme-linked immunosorbent assay and enzyme-linked immunospot assay.
  
  
  RESULTS
  VP2 capsid proteins of HBoV were produced in insect cells infected with a recombinant baculovirus, and the formation of icosahedral VLPs (diameter, 21-25 nm; sedimentation density, 1.33 g/cm(3)) was demonstrated. A significant increase in secretion of VP2-specific interferon-gamma was detected in cultures of peripheral blood mononuclear cells obtained from 69 healthy adults found to be positive for HBoV-specific immunoglobulin G antibodies, compared with control stimulations. In parallel, T cell responses against identically expressed parvovirus B19 VP2 VLPs were frequently observed in the individuals studied, without there being obvious cross-reactions between HBoV and parvovirus B19.
  
  
  CONCLUSIONS
  Data suggest the presence of HBoV-specific immune responses in adults and strongly support a high prevalence of HBoV among humans.
authors.affiliation: Institute of Medical Microbiology and Hygiene, University of Regensburg, Franz-Josef-Strauss Allee 11, Regensburg, Germany.
authors.forename: Juha
authors.initials: J
authors.lastname: Lindner
authors.forename: Sandra
authors.initials: S
authors.lastname: Zehentmeier
authors.forename: Rauli
authors.initials: R
authors.lastname: Franssila
authors.forename: Sascha
authors.initials: S
authors.lastname: Barabas
authors.forename: Josef
authors.initials: J
authors.lastname: Schroeder
authors.forename: Ludwig
authors.initials: L
authors.lastname: Deml
authors.forename: Susanne
authors.initials: S
authors.lastname: Modrow
mesh_terms: D000328:Adult; D000368:Aged; D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D052660:Bocavirus / Q000276:immunology*; D036022:Capsid Proteins / Q000276:immunology*; D002460:Cell Line; D005260:Female; D015658:HIV Infections / Q000276:immunology; D006801:Humans; D007313:Insecta; D007371:Interferon-gamma / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology*; D014764:Viral Proteins / Q000276:immunology*
chemical_list: D000914:Antibodies, Viral; D036022:Capsid Proteins; D014764:Viral Proteins; D007371:Interferon-gamma