Isabel Hennig-Pauka, Katrin Strutzberg-Minder, Paul R Langford
Actinobacillus pleuropneumoniae (APP) remains one of the most significant bacterial respiratory pathogens in swine production worldwide, causing porcine pleuropneumonia with substantial economic impact. Although recent reviews have summarized aspects of APP epidemiology, serotyping, surface-associated virulence determinants, and vaccine development strategies, several complementary research areas have advanced rapidly since the last DISease CONtrol TOOLS (DISCONTOOLS) 2017 report on this bacterium. These include antimicrobial resistance surveillance, chronic persistence mechanisms such as biofilm formation, refined experimental infection models, intracellular survival within host immune cells, and the immunopathological processes driving lung injury. This review focuses on these practical and mechanistic dimensions, emphasizing their relevance for herd-level control, outbreak management, and future therapeutic approaches. Recent genomic studies of multidrug-resistant strains, as well as the development of improved molecular diagnostic tools, are also discussed. Collectively, emerging evidence suggests that APP should not be viewed solely as an extracellular pathogen causing acute disease outbreaks, but rather as an adaptable organism capable of persistence, immune modulation, and endemic circulation in modern pig populations. Addressing these challenges will require integrated strategies that combine antimicrobial stewardship, improved surveillance, and a deeper understanding of host-pathogen interactions.