MOLECULAR CHARACTERIZATION OF A PLASMID ISOLATED FROM RIEMERELLA ANATIPESTIFER

Sixty strains of Riemerella anatipestifer were isolated from ducks and geese with infectious serositis in Taiwan, Sixty per cent of the isol ates (36/60) contained a 3.9 b plasmid, 12% (7/60) contained 6.5 b and 16 b plasmids, 5% (3/60) contained 2.9, 16 and 18 b plasmids and 13% contained no plasmid (14/60), The 3.9 b plasmid (designated as pCFC1) was completely sequenced to determine if it encoded virulence factors. pCFC1 was 27% G-C and had four large open reading frames (ORF), Two o f the ORFs (designated as VapD1 and VapD2) encoded proteins that share d 80, 83, 69 and 67 (VapD1) and 50, 48, 21 and 20% (VapD2) identity wi th virulence-associated proteins of Actinobacillus Actinomycetemcomita ns, Dichelobcater nodosus, Haemophilus influenzae and Neisseria gonorr heae, respectively. pCFC1 also had an ORF (designated as RepA1) that e ncoded a protein with approximately 30% identity to the RepA proteins of Neisseria gonorrhoeae, Campylobactor hyointestinalis and Pseudomona s aeroginosa, The region upstream of the RepA ORF had an A-T-rich regi on that was followed by four 21 bp perfect and one 20 bp imperfect dir ect repeat, The fourth ORF (designated as RepA2) encoded a protein wit h a region that was 44% homologous to the Helicobactor pylori replicat ion protein.