Acute-phase-specific heptapeptide epitope for diagnosis of parvovirus B19 infection

The major capsid protein VP2 of human parvovirus B19, when studied in a den atured form exhibiting linear epitopes, is recognized exclusively by immuno globulin G (Igc) antibodies of patients with acute or recent B19 infection. By contrast, conformational epitopes of VP2 are recognized both by Ige of the acute phase and by IgG of past immunity, In order to localize the VP2 l inear epitope(s) specific for acute-phase Igc, the entire B19 capsid protei n sequence was mapped by peptide scanning using well-characterized acute-ph ase and control sera. A unique heptapeptide epitope showing strong and sele ctive reactivity with the acute-phase IgG was detected and characterized. B y using this linear epitope (VP2 amino acids 344 to 350) and virus-like par ticles exhibiting conformational VP2 epitopes, an innovative approach, seco nd-generation epitope-typing enzyme immunoassay, was set up for improved di agnosis of primary infections by human parvovirus B19.