Actinobacillus pleuropneumoniae does not require urease activity to produce acute swine pleuropneumonia

The role in virulence of Actinobacillus pleuropneumoniae urease activity was investigated.A urease-negative mutant was isolated following transposon mutagenesis with a mini-Tn10 derivative.Both the parent strain and the urease-negative mutant exhibited identical LD 50 values in a murine infection model.Pig challenge confirmed that the urease-negative mutant was fully virulent, since experimental inoculation with 5U10 7 colony forming units resulted in an acute disease indistinguishable from that produced by the wild-type strain at the same dose.Our results demonstrate that urease activity is not required for the development of acute pleuropneumonia.