scholarly journals Plasmid-mediated florfenicol resistance in Pasteurella trehalosi

2006 ◽  
Vol 58 (1) ◽  
pp. 13-17 ◽  
Author(s):  
C. Kehrenberg
Keyword(s):  
Pasteurella Trehalosi

scholarly journals Sequence Diversity and Molecular Evolution of the Leukotoxin (lktA) Gene in Bovine and Ovine Strains ofMannheimia (Pasteurella)haemolytica

2001 ◽  
Vol 183 (4) ◽  
pp. 1394-1404 ◽  
Author(s):  
Robert L. Davies ◽  
Thomas S. Whittam ◽  
Robert K. Selander
Keyword(s):  
Molecular Evolution ◽  
Allelic Diversity ◽  
Pasteurella Haemolytica ◽  
Intragenic Recombination ◽  
Allelic Variants ◽  
Amino Acid Divergence ◽  
History Of ◽  
Nucleotide Divergence ◽  
Pasteurella Trehalosi ◽  
Different Sources

ABSTRACT The molecular evolution of the leukotoxin structural gene (lktA) of Mannheimia (Pasteurella)haemolytica was investigated by nucleotide sequence comparison of lktA in 31 bovine and ovine strains representing the various evolutionary lineages and serotypes of the species. Eight major allelic variants (1.4 to 15.7% nucleotide divergence) were identified; these have mosaic structures of varying degrees of complexity reflecting a history of horizontal gene transfer and extensive intragenic recombination. The presence of identical alleles in strains of different genetic backgrounds suggests that assortative (entire gene) recombination has also contributed to strain diversification in M. haemolytica. Five allelic variants occur only in ovine strains and consist of recombinant segments derived from as many as four different sources. Four of these alleles consist of DNA (52.8 to 96.7%) derived from the lktA gene of the two related species Mannheimia glucosida andPasteurella trehalosi, and four contain recombinant segments derived from an allele that is associated exclusively with bovine or bovine-like serotype A2 strains. The two major lineages of ovine serotype A2 strains possess lktA alleles that have very different evolutionary histories and encode divergent leukotoxins (5.3% amino acid divergence), but both contain segments derived from the bovine allele. Homologous segments of donor and recipient alleles are identical or nearly identical, indicating that the recombination events are relatively recent and probably postdate the domestication of cattle and sheep. Our findings suggest that host switching of bovine strains from cattle to sheep, together with inter- and intraspecies recombinational exchanges, has played an important role in generating leukotoxin diversity in ovine strains. In contrast, there is limited allelic diversity of lktA in bovine strains, suggesting that transmission of strains from sheep to cattle has been less important in leukotoxin evolution.

scholarly journals Serotypes A1 and A2 ofMannheimia haemolyticaare susceptible to genotypic, capsular and phenotypic variations in contrast to T3 and T4 serotypes ofBibersteinia (Pasteurella) trehalosi

2008 ◽  
Vol 280 (1) ◽  
pp. 42-49 ◽  
Author(s):  
Laurence Villard ◽  
Dominique Gauthier ◽  
Françoise Maurin ◽  
Evelyne Borges ◽  
Yves Richard ◽  
...  
Keyword(s):  
Phenotypic Variations ◽  
Pasteurella Trehalosi

scholarly journals Mosaic Structure and Molecular Evolution of the Leukotoxin Operon (lktCABD) in Mannheimia (Pasteurella) haemolytica, Mannheimia glucosida, and Pasteurella trehalosi

2002 ◽  
Vol 184 (1) ◽  
pp. 266-277 ◽  
Author(s):  
Robert L. Davies ◽  
Susan Campbell ◽  
Thomas S. Whittam
Keyword(s):  
Amino Acid ◽  
Molecular Evolution ◽  
Antigenic Variation ◽  
Amino Acid Replacement ◽  
Pasteurella Haemolytica ◽  
Mosaic Structure ◽  
Common Mechanism ◽  
Intragenic Recombination ◽  
Evolutionary Constraint ◽  
Pasteurella Trehalosi

ABSTRACT The mosaic structure and molecular evolution of the leukotoxin operon (lktCABD) was investigated by nucleotide sequence comparison of the lktC, lktB, and lktD genes in 23 Mannheimia (Pasteurella) haemolytica, 6 Mannheimia glucosida, and 4 Pasteurella trehalosi strains. Sequence variation in the lktA gene has been described previously (R. L. Davies et al., J. Bacteriol. 183:1394–1404, 2001). The leukotoxin operon of M. haemolytica has a complex mosaic structure and has been derived by extensive inter- and intraspecies horizontal DNA transfer and intragenic recombination events. However, the pattern of recombination varies throughout the operon and among the different evolutionary lineages of M. haemolytica. The lktA and lktB genes have the most complex mosaic structures with segments derived from up to four different sources, including M. glucosida and P. trehalosi. In contrast, the lktD gene is highly conserved in M. haemolytica. The lktC, lktA, and lktB genes of strains representing the major ovine lineages contain recombinant segments derived from bovine or bovine-like serotype A2 strains. These findings support the previous conclusion that host switching of bovine A2 strains from cattle to sheep has played a major role in the evolution of the leukotoxin operon in ovine strains of M. haemolytica. Homologous segments of donor and recipient alleles are identical, or nearly identical, indicating that the recombinational exchanges occurred relatively recent in evolutionary terms. The 5′ and 3′ ends of the operon are highly conserved in M. haemolytica, which suggests that multiple horizontal exchanges of the complete operon have occurred by a common mechanism such as transduction. Although the lktA and lktB genes both have complex mosaic structures and high nucleotide substitution rates, the amino acid diversity of LktB is significantly lower than that of LktA due to a higher degree of evolutionary constraint against amino acid replacement. The recombinational exchanges within the leukotoxin operon have had greatest effect on LktA and probably provide an adaptive advantage against the host antibody response by generating novel antigenic variation at surface-exposed sites.

scholarly journals Conservation of Expression and N-Terminal Sequences of the Pasteurella haemolytica 31-Kilodalton andPasteurella trehalosi 29-Kilodalton Periplasmic Iron-Regulated Proteins

1999 ◽  
Vol 6 (4) ◽  
pp. 617-620 ◽  
Author(s):  
Louisa B. Tabatabai ◽  
Glynn H. Frank
Keyword(s):  
Polyclonal Antibody ◽  
Pasteurella Haemolytica ◽  
Terminal Sequence ◽  
Similarities And Differences ◽  
Pasteurella Trehalosi ◽  
Cattle And Sheep

ABSTRACT This study examined the conservation of expression of a 31-kDa iron-regulated protein by serotypes of Pasteurella haemolytica and Pasteurella trehalosi associated with pasteurellosis of cattle and sheep. A polyclonal antibody prepared against the purified 31-kDa periplasmic iron-regulated protein fromP. haemolytica serotype A1 showed that all P. haemolytica serotypes expressed similar 31-kDa proteins with identical N-terminal sequences, whereas P. trehalosiserotypes expressed immunologically different 29-kDa proteins with a different N-terminal sequence. Antibody to the 31-kDa iron-regulated protein was a useful tool to distinguish similarities and differences of the iron-regulated proteins of P. haemolytica andP. trehalosi.

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