Cloning of Bordetella pertussis outer membrane proteins in Escherichia coli

We have cloned in Escherichia coli a 40 kb chromosomal DNA fragment of Bordetella pertussis which encoded the synthesis of two major outer membrane proteins specific to this microorganism. The clone harbouring the plasmid pFSH200 has shown modulation of the expression of these proteins when grown on complete solid medium. However, this phenomenon has not occurred in clones harbouring smaller derivatives of plasmid pFSH200 and one such derivative, plasmid pFSH201, has been isolated and further characterized. These results suggest that the large plasmid pFSH200 contained a regulatory sequence affecting the expression of the outer membrane proteins of Bordetella pertussis in Escherichia coli. This sequence is very likely responsible for the antigenic modulation observed in phase I strains of Bordetella pertussis.