Sero- and apx -typing of German Actinobacillus pleuropneumoniae field isolates from 2010 to 2019 reveals a predominance of serovar 2 with regular apx -profile

In this study, 213 GermanA. pleuropneumoniae field isolates retrieved for diagnostic purposes from outbreaks of porcine pleuropneumonia between 2010 and 2019 were genetically serotyped and analyzed regarding theirapx-toxin gene profile using molecular methods. Serotyping revealed a prominent role of serovar 2 in clinical cases (64% of all isolates) and an increase in the detection of this serovar since 2010 in German isolates. Serovar 9/11 followed as the second most frequent serovar with about 15% of the isolates. Furthermore, very recently described serovars 16 (n  = 2) and 18 (n = 8) were detected. Most isolates (93.4%) showedapx-profiles typical for the respective serovar. However, this does not hold true for isolates of serovar 18, as 75% (n  = 6) of all isolates of this serovar deviated uniformly from the “typical”apx-gene profile of the reference strain 7311555. Notably, isolates from systemic lesions such as joints or meninges did not harbor the completeapxICABD operon which is considered typical for highly virulent strains. Furthermore, the extremely low occurrence (n  = 1) of NAD independent (biovar II) isolates in GermanA. pleuropneumoniae was evident in our collection of clinical isolates.
Source: Veterinary Research - Category: Veterinary Research Source Type: research