Characterization and protective activity of a monoclonal antibody against a capsular epitope shared by Streptococcus suis serotypes 1, 2 and 1/2
Characterization and protective activity of a monoclonal antibody against a capsular epitope shared by Streptococcus suis serotypes 1, 2 and 1/2
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DOI：
10.1099/00221287-143-11-3607
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发表时间：
1997-11-01
期刊：
影响因子：
2.8
通讯作者：
Gottschalk, M
中科院分区：
文献类型：
--
作者：
Charland, N;Jacques, M;Gottschalk, M
用猪链球菌2型参考株S735的全细胞免疫BALB/c小鼠，制备单克隆抗体（mAb Z3）。经dot-ELISA筛选，单抗Z3为IgG 2b型，仅与参考株和S.猪血清型1、2和1/2。通过高碘酸盐氧化证明识别的表位本质上是多糖，并且位于胶囊中，因为mAb Z3通过免疫印迹与纯化的胶囊材料反应，并且能够稳定胶囊，如电子显微镜所示。进一步表征表明，mAb Z3可能与胶囊的唾液酸部分特异性反应，这是三种胶囊类型的多糖荚膜材料的共同成分，因为唾液酸酶处理的细胞在免疫印迹或间接ELISA中不与mAb Z3反应。纯化的mAb Z3能显著提高S.猪单核细胞对suis细胞的作用，并激活实验感染小鼠循环中细菌的清除。然而，mAb Z3仅对用最小致死剂量攻击的小鼠提供部分保护。因此，即使S.猪的抗猪链球菌感染的单克隆抗体Z3是一个重要的毒力因子，但Z3识别的抗原表位似乎不参与完全的抗感染保护。
A monoclonal antibody (mAb Z3) was produced using BALB/c mice immunized with whole cells of Streptococcus suis serotype 2 reference strain S735. Screening by dot-ELISA showed that mAb Z3, of isotype IgG2b, reacted only with reference strains and field isolates of S. suis serotypes 1, 2 and 1/2. The recognized epitope was demonstrated to be polysaccharide in nature by periodate oxidation, and located in the capsule, since mAb Z3 reacted with purified capsular material by immunoblotting and was able to stabilize the capsule as shown by electron microscopy. Further characterization indicated that mAb Z3 may react specifically with the sialic acid moiety of the capsule, a common constituent of the polysaccharidic capsular material of the three capsular types, since sialidase-treated cells did not react with mAb Z3 in immunoblotting or indirect ELISA. Purified mAb Z3 was shown to significantly increase the rate of phagocytosis of S. suis cells by porcine monocytes and to activate the clearance of bacteria from the circulation in experimentally infected mice. However, mAb Z3 only offered partial protection to mice challenged with a minimal lethal dose. Thus, even though the capsule of S. suis seems to be an important virulence factor, the epitope recognized by mAb Z3 does not appear to be involved in complete protection against infection.