Actinobacillus pleuropneumoniae, a Gram-negative bacterium, is the causative agent of porcine pleuropneumonia, a highly contagious and often fatal disease. Because current vaccines confer limited protection against A. pleuropneumoniae infection, the development of more effective vaccines is urgently required. | Identification and characterization of a novel stress-responsive outer membrane protein Lip40 from Actinobacillus pleuropneumoniae