a Division of Allergy-Immunology-Rheumatology, Department of Internal Medicine , Chi-Mei Medical Center , Tainan , Taiwan.
b Department of Internal Medicine , National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University , Tainan , Taiwan.
Virulence. 2018 Jan 1;9(1):208-216. doi: 10.1080/21505594.2017.1385691. Epub 2017 Nov 30.
Mounting evidence suggests a connection between human parvovirus B19 (B19) and autoimmune diseases, and especially an association between the B19-VP1 unique region (VP1u) and anti-phospholipid syndrome (APS). However, little is known about the antigenicity of B19-VP1u in the induction of APS-like syndrome. To elucidate the antigenicity of B19-VP1u in the induction of APS, N-terminal truncated B19-VP1u (tVP1u) proteins were prepared to immunize Balb/c mice to generate antibodies against B19-tVP1u proteins. The secreted phospholipase A2 (sPLA2) activities and binding specificity of mice anti-B19-tVP1u antibodies with cardiolipin (CL) and beta-2-glycoprotein I (β2GPI) were evaluated by performing immunoblot, ELISA and absorption experiments. A mice model of passively induced APS was adopted. Although sPLA2 activities were identified in all B19-tVP1u proteins, only amino acid residues 61-227 B19-tVP1u exhibited a higher sPLA2 activity. Autoantibodies against CL and β2GPI exhibited binding activities with all B19-tVP1u proteins. IgG that was purified from mice that had been immunized with amino acid residues 21-227 to 121-227 B19-tVP1u proteins exhibited significantly higher binding activity with CL. IgG that was purified from mice that had been immunized with amino acid residues 21-227, 31-227, 82-227 and 91-227 B19-tVP1u proteins exhibited significantly higher binding activity with β2GPI. Accordingly, significantly higher binding inhibition of CL was detected in the presence of amino acid residues 61-227 and 101-227 B19-tVP1u. Significantly higher binding inhibition of β2GPI was detected in the presence of amino acid residues 21-227, 31-227, 82-227 and 91-227 B19-tVP1u. The mice that received amino acid residues 31-227 or 61-227 anti-tB19-VP1u IgG revealed significant thrombocytopenia and those that received amino acid residues 21-227, 31-227, 61-227, 71-227, 82-227, 91-227, 101-227 or 114-227 anti-tB19-VP1u IgG exhibited significantly prolonged aPTT. These findings provide further information concerning the role of B19-VP1u antigenicity in APS-like autoimmunity.
越来越多的证据表明人类细小病毒 B19（B19）与自身免疫性疾病之间存在关联，尤其是 B19-VP1 独特区域（VP1u）与抗磷脂综合征（APS）之间的关联。然而，关于 B19-VP1u 在诱导 APS 样综合征中的抗原性知之甚少。为了阐明 B19-VP1u 在诱导 APS 中的抗原性，制备了 N 端截断的 B19-VP1u（tVP1u）蛋白，用于免疫 Balb/c 小鼠，以产生针对 B19-tVP1u 蛋白的抗体。通过进行免疫印迹、ELISA 和吸收实验，评估了小鼠抗 B19-tVP1u 抗体与心磷脂（CL）和β2-糖蛋白 I（β2GPI）的分泌型 PLA2（sPLA2）活性和结合特异性。采用被动诱导 APS 的小鼠模型。尽管在所有 B19-tVP1u 蛋白中均鉴定出 sPLA2 活性，但只有 B19-tVP1u 的氨基酸残基 61-227 表现出更高的 sPLA2 活性。针对 CL 和β2GPI 的自身抗体与所有 B19-tVP1u 蛋白均具有结合活性。从用氨基酸残基 21-227 至 121-227 B19-tVP1u 蛋白免疫的小鼠中纯化的 IgG 与 CL 具有显著更高的结合活性。从用氨基酸残基 21-227、31-227、82-227 和 91-227 B19-tVP1u 蛋白免疫的小鼠中纯化的 IgG 与β2GPI 具有显著更高的结合活性。相应地，在存在氨基酸残基 61-227 和 101-227 B19-tVP1u 时，CL 的结合抑制作用明显更高。在存在氨基酸残基 21-227、31-227、82-227 和 91-227 B19-tVP1u 时，β2GPI 的结合抑制作用明显更高。接受氨基酸残基 31-227 或 61-227 抗-tB19-VP1u IgG 的小鼠表现出明显的血小板减少症，而接受氨基酸残基 21-227、31-227、61-227、71-227、82-227、91-227、101-227 或 114-227 抗-tB19-VP1u IgG 的小鼠表现出明显延长的 aPTT。这些发现为 B19-VP1u 抗原性在 APS 样自身免疫中的作用提供了进一步的信息。
