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

最近，Sawada等开发了一种单克隆抗体E87，从与铜绿假单胞菌分离株的广泛交叉反应性来看，该抗体似乎可用于铜绿假单胞菌感染的免疫治疗。本项目对E87抗原的存在和结构进行了研究，得到以下结果。(1)在选择性降解各自的主要O-抗原后，从三种铜绿假单胞菌菌株IFO 3080（Homma血清型M）、IID 1020（血清型G）和T424（血清型G）的O-多糖级分中分离富含鼠李糖的多糖。根据它们的化学组成、1H-NMR和1H-NMR谱的测量以及旋光的测定，可以得出结论，这些多糖具有相同的D-鼠李聚糖结构，-3）-D-Rha（α 1-&gt; 2）-D-Rha（α 1-&gt; 3）-D-Rha（α 1-&gt;），就像来自菌株IID 1008的D-鼠李聚糖一样。<13>(2)在竞争ELISA中，上述富含鼠李糖的多糖制剂以及菌株IID 1008的D-鼠李聚糖以相同程度抑制单克隆抗体E87与铜绿假单胞菌PAC 1细胞的结合。因此，分离的多糖与D-鼠李聚糖在免疫学上无法区分。(3)开发了GDP-D-鼠李糖合成酶的酶测定系统，并且显示该酶存在于测试的13种铜绿假单胞菌血清型中的9种（A、D、F、G、H、I、K、L和M）中。这种酶的分布与单克隆抗体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-鼠李糖连接的脂多糖的可能性。从它们的广泛存在，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.