Hemmings L, McManus D P
Department of Pure and Applied Biology, Imperial College of Science, Technology and Medicine, London, U.K.
Mol Biochem Parasitol. 1991 Jan;44(1):53-61. doi: 10.1016/0166-6851(91)90220-z.
A diagnostic Echinococcus multilocularis antigen gene (EM4) has been expressed using the Escherichia coli expression vector pGEX-1 resulting in the high level synthesis of a readily purifiable, soluble, non-denatured peptide fused to the 26-kDa glutathione-S-transferase of Schistosoma japonicum. This recombinant antigen, on testing by enzyme-linked immunosorbent assay (ELISA) with heterologous human antisera, demonstrated 100% E. multilocularis specificity. Specific anti-EM4 antibody immunoprecipitated a single 66-kDa protein from protoscolex total RNA directed in vitro translation products indicating the probable involvement of post-translational modification in the production of the native EM4 antigens. Southern blotting analysis suggests that the EM4 native antigens are coded for by a single-copy gene and that the genomic organisation of the EM4 related genes in other parasites is not conserved. The nucleotide sequence of the cloned EM4 cDNA molecule has been obtained and the derived amino acid sequence shows no significant homology with other existing protein sequences.
一种用于诊断的多房棘球绦虫抗原基因（EM4）已通过大肠杆菌表达载体pGEX-1进行表达，从而高水平合成了一种易于纯化的可溶性非变性肽，该肽与日本血吸虫26 kDa的谷胱甘肽-S-转移酶融合。用异源人抗血清通过酶联免疫吸附测定（ELISA）对该重组抗原进行检测时，显示出对多房棘球绦虫具有100%的特异性。特异性抗EM4抗体从原头蚴总RNA体外翻译产物中免疫沉淀出一种单一的66 kDa蛋白，这表明翻译后修饰可能参与了天然EM4抗原的产生。Southern印迹分析表明，EM4天然抗原由单拷贝基因编码，并且其他寄生虫中与EM4相关基因的基因组组织不保守。已获得克隆的EM4 cDNA分子的核苷酸序列，推导的氨基酸序列与其他现有蛋白质序列无明显同源性。
