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.
Cruijsen
T
T
Department of Herd Health and Reproduction, Faculty of Veterinary Medicine, Utrecht University, The Netherlands.
van Leengoed
L A
LA
Kamp
E M
EM
Hunneman
W A
WA
Riepema
K
K
Bartelse
A
A
Verheijden
J H
JH
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