Comparison of molecular serotyping methods for Actinobacillus pleuropneumoniae and analysis of atypical serotypes detected in routine diagnostics

• DOI: 10.1016/j.mimet.2025.107132
• Publication Date: 2025-04-15T20:07:49Z
• Authors: Henning Lindhaus; Henning Bischoff; Madita Harms; Theresa Menke; Carina Helmer; Isabel Hennig-Pauka
• Keywords: Actinobacillus pleuropneumoniae; Actinobacillus

Clinical outbreaks due to Actinobacillus pleuropneumoniae (APP) and subclinical infections have high impact on swine health status worldwide although several commercial vaccines are available. Autogenous vaccination programs implemented when APP occur in commercially vaccinated herds. The identification characterization of the involved serotypes is therefore crucial for implementation preventive strategies antimicrobial usage reduction farm. Interpretation serotyping results obtained by different methods might be difficult case mismatching or untypable isolates. In this study two routine methods- a capsular gene based an apx toxin PCR- were compared 151 field 19 reference strains. species was identified after bacterial culture MALDI-TOF-MS followed serotyping. Toxin profiles not accordance with serotype defined capsule PCR 37 % strains which grouped those (1) atypical (cps) patterns (22 %) (2) apxIV length (78 %). Selected further analysed whole genome sequencing. gene-based robustly apxI-III genes all revealed highly variable patterns. For thirteen isolates cps-gene type 6 pattern 2/8/15 could confirmed via WGS. three 9/11 failure cps typing found deletion at 3' cpsF gene. A standardized, precise description apx-toxin as well cps-gene-based can recommended (e.g. 2, profile apxIB, apxII, apxIII).