title: Characterisation of haemolytic RTX toxins produced by Australian isolates of Actinobacillus pleuropneumoniae.
abstract: The haemolytic RTX toxins of 27 isolates of Actinobacillus pleuropneumoniae, representing all serovars that have been isolated in Australia, were characterised. The quantity of protein secreted by these isolates into the media was not significantly different between serovars, but haemolytic activity was detected only in the unconcentrated supernatants from cultures of serovar 1 and 5 isolates. Haemolytic activity in supernatants of serovar 2, 3 and 7 isolates was detected only after the supernatants were concentrated. On Southern hybridisation blots, genomic DNA of serovar 1 and 5 isolates contained regions that were similar to the cloned structural genes for ApxI (apxIA) and for ApxII (apxIIA). In contrast, genomic DNA of serovar 2, 3 and 7 isolates only contained regions similar to, if not identical with, the cloned apxIIA gene. The haemolytic activity of the culture supernatant depends on the type or composition of media and adaptability of the bacteria to in-vitro cultivation. Low passage cultures of A pleuropneumoniae, which were characterised by waxy colonies, produced significantly weaker haemolytic activity than A pleuropneumoniae after several passages in vitro.
authors.affiliation: School of Veterinary Science, University of Melbourne, Parkville, Victoria.
authors.forename: S
authors.initials: S
authors.lastname: Tarigan
authors.forename: R F
authors.initials: RF
authors.lastname: Slocombe
authors.forename: G F
authors.initials: GF
authors.lastname: Browning
authors.forename: P J
authors.initials: PJ
authors.lastname: Blackall
mesh_terms: D000189:Actinobacillus Infections / Q000453:epidemiology / Q000378:metabolism / Q000662:veterinary; D016977:Actinobacillus pleuropneumoniae / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D000818:Animals; D001315:Australia / Q000453:epidemiology; D001426:Bacterial Proteins / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D001427:Bacterial Toxins / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D015139:Blotting, Southern; D004269:DNA, Bacterial / Q000032:analysis / Q000737:chemistry / Q000235:genetics; D006460:Hemolysin Proteins / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D013552:Swine; D013553:Swine Diseases / Q000453:epidemiology / Q000378:metabolism / Q000382:microbiology
chemical_list: C085361:ApxII toxin, bacteria; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D004269:DNA, Bacterial; D006460:Hemolysin Proteins; C087744:ApxI toxin, Bacteria