Cross-protection between Actinobacillus pleuropneumoniae biotypes-serotypes in pigs.
Four groups of hysterectomy-derived and colostrum-deprived pigs were intranasally inoculated with an Actinobacillus pleuropneumoniae biotype 1-serotype 2 strain (producing RTX toxins ApxII and ApxIII. 6 pigs), an A. pleuropneumoniae biotype 1-serotype 10 strain (producing ApxI. 5 pigs), an A. pleuropneumoniae biotype 2-serotype 2 strain (producing ApxII, 5 pigs) or saline (controls, 7 pigs). All pigs were exposed to A. pleuropneumoniae biotype 1-serotype 2 endobronchial challenge. After challenge, severe clinical signs were observed in all control pigs, one pig immunized with the A. pleuropneumoniae biotype 1-serotype 10 strain and two pigs immunized with the A. pleuropneumoniae biotype 2-serotype 2 strain. These pigs died within 36 h after challenge and 20 to 50% of the lungs were macroscopically affected. In the other pigs, clinical signs were mild or absent and no or only small, focal lung lesions were observed when euthanized at 48 h after challenge. At the time challenge neutralizing antibodies against ApxI only. ApxII only and both ApxII and III were present in sera of pigs immunized with the A. pleuropneumoniae biotype 1-serotype 10 strain, the A. pleuropneumoniae biotype 2-serotype 2 strain and the A. pleuropneumoniae biotype 1-serotype 2 strain, respectively. These results indicate that immune mechanisms other than Apx neutralizing antibodies were involved in partial cross-protection of pigs immunized against A. pleuropneumoniae biotype 1-serotype 10 and challenged with the A. pleuropneumoniae biotype 1-serotype 2.
Haesebrouk
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F
Laboratory of Veterinary Bacteriology and Mycology, Faculty of Veterinary Medicine, University of Gent, Merelbeke, Belgium. freddy.haesebrouck@rug.ac.be
Van de Kerkhof
A
A
Dom
P
P
Chiers
K
K
Ducatelle
R
R
D000189:Actinobacillus Infections / Q000276:immunology / Q000382:microbiology / Q000517:prevention & control / Q000662:veterinary*; D016977:Actinobacillus pleuropneumoniae / Q000145:classification / Q000276:immunology*; D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood; D001427:Bacterial Toxins / Q000096:biosynthesis; D015373:Bacterial Typing Techniques; D007114:Immunization / Q000662:veterinary; D012703:Serotyping; D013552:Swine; D013553:Swine Diseases / Q000276:immunology* / Q000382:microbiology / Q000517:prevention & control
D000907:Antibodies, Bacterial; D001427:Bacterial Toxins