Holt R G, Perry S E
Department of Microbiology, Meharry Medical College, Nashville, Tennessee 37208.
J Gen Microbiol. 1990 Jul;136(7):1351-6. doi: 10.1099/00221287-136-7-1351.
A gene of Streptococcus sobrinus 6715 (serotype g) designated spaB and encoding a surface protein antigen was isolated from a cosmid gene bank. A 5.4 kb HindIII/AvaI DNA fragment containing the gene was inserted into plasmid pBR322 to yield plasmid pXI404. Analysis of plasmid-encoded gene products showed that the 5.4 kb fragment of pXI404 encoded a 195 kDa protein. Southern blot experiments revealed that the 5.4 kb chromosomal insert DNA had sequence similarity with genomic DNA of S. sobrinus 6715, S. sobrinus B13 (serotype d) and Streptococcus cricetus HS6 (serotype a). The recombinant SpaB protein (rSpaB) was purified and monospecific antiserum was prepared. With immunological techniques and the anti-rSpaB serum, we have shown: (1) that the rSpaB protein has physico-chemical and antigenic identity with the S. sobrinus SpaB protein, (2) the presence of cross-reactive proteins in the extracellular protein of serotypes a and d of the mutans group of streptococci and (3) that the SpaB protein is expressed on the surface of mutans streptococcal serotypes a, d and g.
从一个黏粒基因文库中分离出了一株远缘链球菌6715（血清型g）的名为spaB且编码一种表面蛋白抗原的基因。将含有该基因的一个5.4 kb HindIII/AvaI DNA片段插入质粒pBR322中，得到质粒pXI404。对质粒编码的基因产物的分析表明，pXI404的5.4 kb片段编码一种195 kDa的蛋白质。Southern杂交实验显示，5.4 kb的染色体插入DNA与远缘链球菌6715、远缘链球菌B13（血清型d）和仓鼠链球菌HS6（血清型a）的基因组DNA具有序列相似性。纯化了重组SpaB蛋白（rSpaB）并制备了单特异性抗血清。利用免疫技术和抗rSpaB血清，我们已经证明：（1）rSpaB蛋白与远缘链球菌SpaB蛋白具有物理化学和抗原同一性，（2）变形链球菌组血清型a和d的细胞外蛋白中存在交叉反应蛋白，以及（3）SpaB蛋白在变形链球菌血清型a、d和g的表面表达。
