The association of VP1 unique region protein in acute parvovirus B19 infection and anti-phospholipid antibody production

Abstract

Background Previous studies have postulated a connection between human parvovirus B19 (B19) infection and anti-phospholipid antibodies (aPL). Recently, the phospholipase domain of B19 has been linked to B19-VP1 unique region (VP1u). To elucidate the roles of VP1u in B19 infection and aPL production, the major reactivity of anti-B19-VP1u, anti-cardiolipin antibody (aCL), and anti-beta2-glycoprotein I (β2GPI) antibody was evaluated. Methods Sera from 102 clinically suspected cases of B19 infection were analyzed by nested PCR and ELISA. Humoral responses of anti-B19-VP1u and anti-B19-VP1uD175A IgM/IgG antibodies, aCL and the anti-β2GPI antibody were assessed by Western blot and ELISA. Absorption experiments were also performed to determine the binding specificity of immunoglobulins to B19-VP1u, CL and β2GPI. Results Sera from patients with the diagnostic pattern DNA +/IgM +/IgG + had a high frequency (57%) for recognition of CL and β2GPI. Furthermore, adsorption experiments were performed by adding purified B19-VP1u, which partially suppressed the reactivity of anti-B19VP1u to CL and β2GPI. Conclusions Serum from patients with acute B19 infection has a high frequency in recognition of CL and β2GPI, and the phospholipase domain observed in the B19-VP1u may have contributed to the production of aPL. These findings may provide a clue for understanding the roles of B19-VP1u in B19 infection and aPL production.