Lipopolysaccharides in Pseudomonas aeruginosa : Structure and biological activity of D-rhamnan-linked lipopolysaccharides

最近，Sawada等人研制出了一种单抗E87。从对铜绿假单胞菌广泛的交叉反应来看，该抗体似乎可用于铜绿假单胞菌感染的免疫治疗。本课题对E87抗原的存在和结构进行了研究，得到以下结果：(1)三株铜绿假单胞菌IFO 3080(Homma血清型M型)、IID 1020(血清型G型)和T424(血清型G型)的O-多糖组分经选择性降解后得到富含鼠李糖的多糖。根据它们的化学组成、~1H和~1H；~(13)GT；~(13)C-核磁共振谱的测定以及旋光度的测定，这些多糖具有相同的D-鼠李糖结构，-3)-D-Rha(alpha1-&gt；2)-D-Rha(alpha1-&gt；3)-D-Rha(alpha1-&gt；(2)在竞争酶联免疫吸附试验中，上述富含鼠李糖的多糖制剂和菌株IID 1008的D-鼠李糖均能抑制单抗E87与铜绿假单胞菌PAC-1细胞的结合。建立了国内生产总值-D-鼠李糖合成酶的检测体系，结果表明该酶存在于13个铜绿假单胞菌的9个血清型中(A、D、F、G、H、I、K、L和M)。这种酶的分布与单抗E87与这些细胞的结合谱密切相关。上述结果有力地支持了E87抗原是D-鼠李聚糖连接的内毒素的可能性。由于它们的广泛存在，D-鼠李聚糖连接的脂多糖可能是铜绿假单胞菌的共同抗原。

Recently, a monoclonal antibody E87 has been developed by Sawada et al. From the wide cross-reactivity againsy P. aeruginosa isolates, this antibody seems to be useful in immunotherapy for P. aeruginosa infection. In this project the occurrence and structure of E87 antigen were studied, and the following results are obtained.(1) Rhamnose-rich polysaccharides were isolated from the O-polysaccharide fractions of three P. aeruginosa strains, IFO 3080 (Homma serotype M), IID 1020 (serotype G), and T424 (serotype G), after selective degradation degradation of the respective major O-antigens. On the basis of their chemical composition, measurement of ^1H - and ^<13>C-NMR spectra, and determination of optical rotatory, it is concluded that these polysaccharides have the same D-rhamnan structure, -3)-D-Rha(alpha1->2)-D-Rha(alpha1->3)-D-Rha(alpha1->, just like D-rhamnan from the strain IID 1008.(2) In competitive ELISA, the above rhamnose-rich polysaccharide preparations as well as the D-rhamnan of strain IID 1008 inhibited, in the same extent, the binding of monoclonal antibody E87 to P. aeruginosa PAC 1 cells. Thus, the isolated polysaccharides are immunologically indistinguishable from the D-rhamnan.(3) The enzyme assay system for GDP-D-rhamnose synthetase was developed, and it was shown that this enzyme occurs in nine (A, D, F, G, H, I, K, L, and M) of tested thirteen serotypes of P. aeruginosa. This enzyme distribution was closely correlated to the binding spectrum of monoclonal antibody E87 to these cells.The above results strongly supports a possibility that E87 antigen is D-rhamnan- linked lipopolysaccharides. From their wide occurrence, the D-rhamnan-linked lipo polysaccharide may be a common antigen in P. aeruginosa.