Frey J, Perrin J, Nicolet J
Institute for Veterinary Bacteriology, University of Berne, Switzerland.
Infect Immun. 1989 Jul;57(7):2050-6. doi: 10.1128/iai.57.7.2050-2056.1989.
The genetic determinant of the cohemolysin which is responsible for the CAMP phenomenon, a cohemolysis, of Actinobacillus pleuropneumoniae was cloned in Escherichia coli. Total DNA from the A. pleuropneumoniae serotype 1 type strain 4074 was used to construct a gene library in plasmid pUC18 in E. coli JM83. A total of 10,500 clones containing recombinant plasmids have been screened for hemolysis on blood plates. Fifty-five clones which showed a weak hemolytic response after 24 to 48 h of incubation were screened for the CAMP reaction with Staphylococcus aureus. This led to the identification of one clone which showed a positive CAMP reaction. Immunoblot analysis revealed that the recombinant strain expressed a protein with a molecular mass of 27,000 daltons, similar in size to the CAMP protein of the group B streptococci. Rabbit antibodies against the CAMP+ clone neutralized the CAMP reaction mediated by the E. coli strain containing the cloned CAMP gene as well as that of A. pleuropneumoniae. Antibodies raised against the cloned CAMP cohemolysin cross-reacted with Streptococcus agalactiae protein B. We designate the 27,000-dalton molecule CAMP factor protein and name its corresponding gene cfp.
导致胸膜肺炎放线杆菌CAMP现象（一种协同溶血现象）的协同溶血素的遗传决定因素在大肠杆菌中被克隆。来自胸膜肺炎放线杆菌血清型1型菌株4074的总DNA被用于构建大肠杆菌JM83中质粒pUC18的基因文库。在血平板上对总共10500个含有重组质粒的克隆进行溶血筛选。筛选出55个在孵育24至48小时后显示出微弱溶血反应的克隆，用于与金黄色葡萄球菌进行CAMP反应检测。这导致鉴定出一个显示阳性CAMP反应的克隆。免疫印迹分析表明，重组菌株表达了一种分子量为27000道尔顿的蛋白质，其大小与B组链球菌的CAMP蛋白相似。针对CAMP+克隆的兔抗体中和了含有克隆CAMP基因的大肠杆菌菌株以及胸膜肺炎放线杆菌介导的CAMP反应。针对克隆的CAMP协同溶血素产生的抗体与无乳链球菌B蛋白发生交叉反应。我们将这种27000道尔顿的分子命名为CAMP因子蛋白，并将其相应的基因命名为cfp。
