ENDOBRONCHIAL INOCULATION WITH APX TOXINS OF ACTINOBACILLUS-PLEUROPNEUMONIAE LEADS TO PLEUROPNEUMONIA IN PIGS

To establish the role of the Apr toxins in the pathogenesis of porcine pleuropneumonia, specific-pathogen-free pigs were inoculated deeply e ndobronchially with either culture filtrates of Actinobacillus pleurop neumoniae serotype 8 or 9, culture filtrates depleted of the Apr toxin s by affinity chromatography, depleted culture filtrate supplemented w ith purified recombinant Apr toxins (rApx), or purified rApx toxins al one, Results of these experiments indicate that ApxI, ApxIII, and, to a lesser extent, ApxII are the bacterial factors that trigger the deve lopment of clinical symptoms and lung lesions typical for porcine pleu ropneumonia.