Intra-specific diversity and host specificity within Pasteurella haemolytica based on variation of capsular polysaccharide, lipopolysaccharide and outer-membrane proteins

Abstract

Intra-specific diversity within Pasteurella haemolytica was assessed by analysing variation in the capsular polysaccharide (serotypes), lipopolysaccharide (LPS) and outer-membrane proteins (OMPs) of 184 isolates recovered from cattle and sheep. Four of 12 serotypes comprised 83% of the total number of isolates, including A1 and A2 as the most frequently recovered serotypes from cattle and sheep, respectively. Nine distinct LPS profiles were identified. Four different core-ol igosaccharide patterns were present, each of which occurred alone as rough LPS and also in association with a single 0-antigen profile as smooth LPS; the ninth LPS type was also smooth but had a different O-antigen profile. The capsular serotypes could be divided into four groups based on the dominant LPS profile within each serotype: (1) Al, A6, A9, A12 and A5; (2) A2, A8, A14 and A16; (3) A7 and A13; and (4) A l l . Smooth LPS of type IA, which was found only in the first group, was associated primarily with bovine disease isolates, whereas rough LPS of types 1B and 3B were associated primarily with the group 2 serotypes and ovine disease isolates. Similarly, the variation of OMP profiles generated three groups: (1) Al, A6, A9, A12, A5 and A8; (2) A2, A14 and A16; and (3) A7, A l l and A13. Isolates belonging to groups 2 and 3 exhibited greater diversity in their OMP profiles than those belonging to group 1. Although the majority of group 3 isolates possessed profiles unique to that group, a smaller number of A7 isolates possessed profiles with similarities to those of serotypes A1 or A2. OMP profiles clearly differentiated bovine from ovine isolates of the same serotypes. The association both of specific LPS and OMP profiles with bovine or ovine disease isolates suggested a correlation between specific cell-surface structures and host specificity. The combined analysis of capsular serotypes, LPS types and OMP profiles identified seven major groups within P. haemolytica which were responsible for 59% of the disease cases, suggesting a clonal structure for this species. Overall, comparison of the capsular serotypes, LPS types and OMP profiles proved extremely useful for assessing diversity within P. haemolytica.

Characterization and comparison of Pasteurella multocida strains associated with porcine pneumonia and atrophic rhinitis

“…Outer membranes were prepared by Sarkosyl extraction as described previously (Davies et al, 1992;Davies & Donachie, 1996). The protein concentrations were determined by the modified Lowry procedure (Markwell et al, 1978) and the OMPs were adjusted to 2·0 mg ml À1 in 20 mM Tris/HCl (pH 7·2) and stored at À85 8C.…”

“…The OMPs were separated by SDS-PAGE in 12 % (w/v) resolving gels (Hoefer SE600 electrophoresis apparatus) using the SDS discontinuous system of Laemmli (1970) as described previously (Davies et al, 1992;Davies & Donachie, 1996). Unless otherwise stated, all samples were heated at 100 8C for 5 min prior to electrophoresis.…”

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

“…For example, serotype A1 and A6 strains account for almost all cases of bovine pneumonic pasteurellosis, whereas serotype A2 and A7 isolates are the major causes of disease in sheep. It has also been shown that bovine and ovine isolates of the same serotype, e.g., A1, A2, or A6, can be distinguished by differences in chromosomal genotype (13) or outer membrane protein (OMP) profiles (10). The inference is that natural populations of M. haemolytica consist of distinct evolutionary lineages that are differentially adapted to either cattle or sheep (13).…”

Serotypic diversity and sequence variation of the ompA gene among Mannheimia haemofytica isolates from domestic ruminants

“…Serotypes A5 and A6 were recovered at very low rates (2.9% and 4.3% respectively) and serotypes A8, Al4 and A16 were not found at all. Interestingly enough, serotype A2 was the only one recovered from goats, suggesting that a much wider range of serotypes is ) and in ovine isolates from the UK, Germany and the USA (Davics and Donachic 1996). However the isolation rate of the remaining serotypes clearly varies among European countries.…”