Clonal analysis of the Actinobacillus pleuropneumoniae population in a geographically restricted area by multilocus enzyme electrophoresis

Abstract

The genetic diversity among 250 isolates of ActinobaciUus pkuropneumoniae from lungs of pigs with pleuropneumonia and from tonsils of apparently healthy pigs at slaughter was estimated by multilocus enzyme electrophoresis. The Danish strains were derived from both specific-pathogen-free and conventional herds. Sixty-six percent of the isolates belonged to three electrophoretic types (ETs) of a total of 37 ETs detected. While five biotype 2 isolates constituted a separate ET closely related to biotype 1 isolates, the type strain of the species (Shope 4074) belonged to its own ET, with a genetic distance of 0.30 from its nearest neighbor. Isolates of serotypes traditionally considered to have less pathogenic potential (serotypes 6, 10, and 12) from herds with acute outbreaks of pleuropneumonia belonged to the same ETs as isolates from apparently healthy pigs, suggesting that factors such as cross immunity and management may lead to divergent clinical results. Isolates from four herds harboring more than one serotype showed distinct profiles between the serotypes, indicating no or only limited chromosomal recombination among clones. Isolates from tonsils belonged to the same ET as isolates from lungs. The same ET was isolated from widely different parts of the world. Evidence from this study indicates that multilocus enzyme electrophoresis may be a valuable tool for the epidemiological analysis of A. pleuropneumoniae.

Genomic relationships of Actinobacillus pleuropnewmoniae serotype 2 strains evaluated by ribotyping, sequence analysis of ribosomal intergenic regions, and pulsed‐field gel electrophoresis

“…Knowledge of the clonal structures of a species is important in understanding results obtained from epidemiological studies. The difficulties in developing applicable typing methods for studying the epidemiology of A. pleuropneumoniae (Sirois and Higgins 1991;Mo Âller et al 1992) might be due to limited genetic diversity of this organism or lack of geographically and epidemiologically independent isolates. For the same Fig.…”

“…Consequently, the epidemiology of the infection needs to be subjected to critical examination in order to obtain information which will allow prevention and control of the disease. Serotyping represents a well established typing system for A. pleuropneumoniae, but as a restricted number of serotypes tends to dominate in different regions or countries (MacInnes et al 1990;Mo Âller et al 1992), this typing system often fails to provide substantial epidemiological information. In Denmark, the most prevalent A. pleuropneumoniae infection is caused by serotype 2 strains (Mo Âller et al 1992).…”

“…Serotyping represents a well established typing system for A. pleuropneumoniae, but as a restricted number of serotypes tends to dominate in different regions or countries (MacInnes et al 1990;Mo Âller et al 1992), this typing system often fails to provide substantial epidemiological information. In Denmark, the most prevalent A. pleuropneumoniae infection is caused by serotype 2 strains (Mo Âller et al 1992). This serotype also dominates in Holland (Kamp et al 1987), Hungary (Molnár 1990), Switzerland (Keller 1988), Norway (Falk et al 1991), Japan (Kume et al 1986), Sweden (Gunnarsson et al 1978), the former Czechoslovakia (Skollova and Gois 1987), Belgium (Dom et al 1994) and Germany (Schimmel and Hass 1983).…”

“…This serotype also dominates in Holland (Kamp et al 1987), Hungary (Molnár 1990), Switzerland (Keller 1988), Norway (Falk et al 1991), Japan (Kume et al 1986), Sweden (Gunnarsson et al 1978), the former Czechoslovakia (Skollova and Gois 1987), Belgium (Dom et al 1994) and Germany (Schimmel and Hass 1983). Previous studies have shown that strains within a given serotype of A. pleuropneumoniae are genetically very similar (Mo Âller et al 1992;Hampson et al 1993).…”

Actinobacillus pleuropneumoniae Serotype‐2 Antibodies in Sow Colostrum in Finnish Pig‐health‐scheme Herds

“…The virulence of different serotypes also seems to vary geographically. In Denmark, serotype-2 infections are usually acute, but in some herds the infection has been subclinical (NIELSEN, 1988;M0LLER et al, 1992). Serotype 2 is also the most prevalent in Sweden, but it seldom causes acute epidemics (BESKOW et al, 1989).…”