title: Both ApxI and ApxII of Actinobacillus pleuropneumoniae serotype 1 are necessary for full virulence.
abstract: Most serotypes of A. pleuropneumoniae produce more than one toxin in vivo. To determine the value of the production of more than one toxin in the development of disease, we tested the pathogenicity of isogenic strains of A. pleuropneumoniae serotype 1 that are mutated in the toxin genes apxIA and/or apxIIA or in the transport genes apxIBD. Bacteria mutated in both apxIA and apxIIA, or in apxIBD, were unable to induce pathological lesions, thereby confirming the conclusion that ApxI and ApxII are essential for the pathogenesis of pleuropneumonia. Infection with isogenic strains lacking either ApxI or ApxII did not consistently lead to pleuropneumonia unlike the parent strain S4074. ApxII seemed at least as important as ApxI for the development of clinical and pathological symptoms. Only one of the four pigs inoculated with a mutant strain unable to produce ApxII developed mild pneumonia whereas two out of the three pigs inoculated with a mutant strain unable to produce ApxI developed more severe lesions. The results indicate that both ApxI and ApxII of A. pleuropneumoniae serotype 1 are necessary for full virulence.
authors.affiliation: Division of Infectious Diseases and Food Chain Quality, Institute for Animal Science and Health, ID-Lelystad, P.O. Box 65, 8200 AB Lelystad, The Netherlands. b.k.h.l.boekema@bio.uu.nl
authors.forename: Bouke K H L
authors.initials: BK
authors.lastname: Boekema
authors.forename: Elbarte M
authors.initials: EM
authors.lastname: Kamp
authors.forename: Mari A
authors.initials: MA
authors.lastname: Smits
authors.forename: Hilde E
authors.initials: HE
authors.lastname: Smith
authors.forename: Norbert
authors.initials: N
authors.lastname: Stockhofe-Zurwieden
mesh_terms: D000189:Actinobacillus Infections / Q000382:microbiology / Q000473:pathology / Q000662:veterinary*; D016977:Actinobacillus pleuropneumoniae / Q000235:genetics / Q000472:pathogenicity*; D000818:Animals; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D001831:Body Temperature; D016207:Cytokines / Q000097:blood; D006460:Hemolysin Proteins; D006651:Histocytochemistry / Q000662:veterinary; D007958:Leukocyte Count / Q000662:veterinary; D008168:Lung / Q000382:microbiology / Q000473:pathology; D016297:Mutagenesis, Site-Directed; D011001:Pleuropneumonia / Q000382:microbiology / Q000473:pathology / Q000662:veterinary*; D011897:Random Allocation; D013552:Swine; D013553:Swine Diseases / Q000382:microbiology*; D014774:Virulence
chemical_list: C085361:ApxII toxin, bacteria; D001426:Bacterial Proteins; D016207:Cytokines; D006460:Hemolysin Proteins; C087744:ApxI toxin, Bacteria