IN-VIVO AND IN-VITRO STABILITY OF THE BROAD-HOST-RANGE CLONING VECTORPBBR1MCS IN 6 BRUCELLA SPECIES

Previous studies have shown that the broad-host-range plasmid pBBR1MCS can be used for genetic complementation in Brucella abortus. To exten d these observations, the in vivo and in vitro stability of pBBR1MCS w as evaluated in the six currently recognized species of the genus Bruc ella. pBBR1MCS was readily introduced into all of the strains tested b y electroporation and was stably maintained in broth cultures without antibiotic selection during five serial passages over a 10-day period. Furthermore, isolates of all six Brucella strains containing pBBR1MCS obtained from the spleens of BALB/c mice 1 week postinfection maintai ned the plasmid. Although pBBR1MCS maintains the mobilization locus pr esent in the parental plasmid pBBR1CM, attempts to detect transfer of pBBR1MCS between Brucella strains by conjugation were unsuccessful. Th ese results demonstrate the in vitro and in vivo stability of pBBR1MCS in Brucella spp. and reinforce the usefulness of this cloning vector for the genetic analysis of these organisms. (C) 1995 Academic Press, Inc.