The association of anti-parvovirus B19-VP1 unique region antibodies with antiphospholipid antibodies in patients with antiphospholipid syndrome.
BACKGROUND
Human parvovirus B19 (B19) infection has been identified as a trigger of antiphospholipid syndrome (APS). However, the precise role of B19-VP1 unique region (VP1u) in patients with antiphospholipid syndrome remains unclear.


METHODS
IgM and IgG against B19-VP, and serum levels of antibodies directed against cardiolipin (CL), beta2-glycoprotein-I (beta2GPI) and phospholipid (PhL) were determined using ELISA in 45 APS patients. Humoral responses of anti-B19-VP1u were assessed by Western blot and B19 DNA was detected by nested PCR. Absorption experiments were performed using B19-VP1u protein to determine the binding specificity of antiphospholipid antibodies (aPL).


RESULTS
One and 18 of 45 APS patients had detectable levels of anti-B19-VP IgM and anti-B19-VP IgG, indicating recent and past infection respectively. All serum samples from APS patients with diagnostic pattern DNA(-)/IgM(-)/IgG(+) had anti-B19-VP1u activity. APS patients with anti-B19-VP1u antibody had a 4-fold increased risk for recurrent vascular thrombosis compared with those without anti-B19-VP1u antibody. The binding inhibition of CL, beta2GPI, and PhL by absorption with B19-VP1u ranged from 31.4% to 91.1%, 0.8% to 59.8% and 20.2% to 72.1% respectively. Significantly higher inhibition to beta2GPI by B19-VP1u absorption was observed in APS patients with anti-B19-VP1u antibody than in those without anti-B19-VP1u antibody.


CONCLUSIONS
We show a close association of B19 infection with aPL production and suggest B19-VP1u may be of pathogenetic importance in some patients with APS.
Chen
Der-Yuan
DY
Department of Allergy, Immunology and Rheumatology, Taichung Veterans General Hospital, Taichung, Taiwan, ROC.
Tzang
Bor-Show
BS
Chen
Yi-Ming
YM
Lan
Joung-Liang
JL
Tsai
Chun-Chou
CC
Hsu
Tsai-Ching
TC
D000042:Absorption; D000328:Adult; D017152:Antibodies, Antiphospholipid / Q000097:blood / Q000276:immunology*; D016736:Antiphospholipid Syndrome / Q000097:blood / Q000175:diagnosis / Q000276:immunology*; D036022:Capsid Proteins / Q000737:chemistry* / Q000276:immunology*; D004279:DNA, Viral / Q000097:blood; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood / Q000276:immunology; D007075:Immunoglobulin M / Q000097:blood / Q000276:immunology; D008297:Male; D016732:Parvovirus B19, Human / Q000276:immunology*
D017152:Antibodies, Antiphospholipid; D036022:Capsid Proteins; D004279:DNA, Viral; D007074:Immunoglobulin G; D007075:Immunoglobulin M; C095547:capsid protein VP1, parvovirus B19