Prevalence and development of antibodies neutralizing the haemolysin and cytotoxin of Actinobacillus pleuropneumoniae in three infected pig herds.
Sero-epidemiological studies were carried out in pigs aged 1 to 24 weeks in three herds in which Actinobacillus pleuropneumoniae was endemic. The sera were tested in the complement-fixation test and for their ability to neutralize the haemolytic and cytotoxic activities of the A. pleuropneumoniae serotypes isolated from the herds. Almost all (98%) sera from 1-week-old piglets neutralized the haemolytic and cytotoxic activities but only 21% fixed complement. At the end of the finishing period, most pigs (82%) had sera that neutralized haemolytic and cytotoxic activities and only 22% fixed complement. In longitudinal studies the neutralization titres decreased during the first 12-13 weeks of age. Thereafter, 75% of the pigs had increased titres in the haemolysin- and cytotoxin-neutralization tests and only 5% of the pigs had increased titres in the complement-fixation test. In none of these pigs were clinical signs of pleuropneumonia seen. Thus in these endemically infected herds the prevalence of complement-fixing antibodies was low, whereas the prevalence of neutralizing antibodies was high. The fact that serum-neutralizing titres are low in 12-week-old pigs might be the reason that pigs of this age are the most vulnerable to the disease.
Department of Herd Health and Reproduction, Faculty of Veterinary Medicine, Utrecht University, The Netherlands.
T
T
Cruijsen
L A
LA
van Leengoed
E M
EM
Kamp
W A
WA
Hunneman
K
K
Riepema
A
A
Bartelse
J H
JH
Verheijden
D000189:Actinobacillus Infections / Q000453:epidemiology / Q000276:immunology / Q000382:microbiology / Q000662:veterinary*; D016977:Actinobacillus pleuropneumoniae / Q000276:immunology*; D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood* / Q000494:pharmacology; D003168:Complement Fixation Tests; D003430:Cross-Sectional Studies; D003603:Cytotoxins; D004196:Disease Outbreaks / Q000662:veterinary; D006460:Hemolysin Proteins / Q000187:drug effects; D008137:Longitudinal Studies; D009500:Neutralization Tests; D015995:Prevalence; D013552:Swine; D013553:Swine Diseases / Q000453:epidemiology / Q000276:immunology* / Q000382:microbiology
D000907:Antibodies, Bacterial; D003603:Cytotoxins; D006460:Hemolysin Proteins