The induction of specific protection against Actinobacillus pleuropneumoniae infection by specific DLE

Immunoprophylactic and immunotherapeutic effects of specific actinobacillus DLE (dialysable leukocyte extract) were studied in model pigs experimentally infected with Actinobacillus pleuropneumoniae. Specific DLE used for immunoprophylactic purposes was administered intramuscularly to pigs either in two doses in combination with one dose of actinobacillus vaccine (1st group) or in a single dose (2nd group). All animals of the two experimental groups survived the intranasal A. pleuropneumoniae challenge (2 x 2 ml 2-5 x 10(10) c.f.u.) while 3 of 5 animals of the control group died of haemorrhagic-necrotic fibrinous pneumonia. DLE administered to pigs for immunotherapeutic purposes was applied intravenously in two doses 1 and 5 h after the actinobacillus challenge (1st group), and in a single dose 5 h following the challenge (2nd group). All animals of the first group survived the challenge while 3 out of 5 animals of the second group and 4 out of 5 animals of the control group died during the experiment.