Study on Antibody Dynamics against Porcine Contagious Pleuropneumonia in Piglets

In order to provide basis for establishing a scientific and reasonable immune procedure against porcine contagious pleuropneumonia in pig farms, antibody dynamics in piglets inoculated with two vaccines against porcine contagious pleuropneumonia （ APP-1,2, 7 ） were detected. The result showed that average antibody blocking rate and antibody positive rate in piglets inoculated with two vaccines against porcine contagious pleuropneumonia exhibited similar variation trend. At 21 day after primary vaccination, average antibody blocking rate and antibody positive rate against porcine contagious pleuropneumonia in piglets reached the peak and then declined gradually. After secondary vaccination, average antibody blocking rate and antibody positive rate against porcine contagious pleuropneumonia in piglets increased gradually, which reached the second peak at 30 day after secondary vaccination （60 day after primary vaccination） ; subsequently, average antibody blocking rate declined gradually but still remained at a high level; antibody positive rate had little change. Average antibody blocking rate against APP-1 was slightly lower than the critical level of antibody protection at 44 day after primary vaccination ; antibody positive rate was slightly higher than the qualification rate at 37 day after primary vaccination; average antibody blocking rate against APP-7 was close to the critical level of antibody protection at 30 day after primary vaccina- tion, suggesting that piglets should be inoculated twice with polyvaccine against porcine contagious pleuropneumonia during the entire growth period, and the secondary vaccination should be performed at 30 -37 day after primary vaccination.

Study on Growth and Decline Law of Contagious Pleuro-pneumonia in Piglets

In order to establish the immune procedure for Actinobacillus pleuropneumonia and to determine the date for the first immunization on piglets, the growth and decline law of A. pleuropneumonia material antibodies in the piglets borne by cows inoculated with A. pleuropneumonia vaccines （type I, II, and VII） before delivery was detected. The results showed that type I, II, and VII maternal antibodies in piglets decreased gradually with the age growing overall, and was at the critical protection value at the ages of 42-50 days （type I） and 28 days （type VII）, lower than the quantification rate; and the antibodies all turned to be negative until the ages of 70 days （type I）, 60 days （type VII） and 35 days （type II）. The first immunization should be carried out at the age of 42-50 days using type I A. pleuropneumonia vaccine, and at the age of 28 days using type VII A. pleuropneumonia vaccine. However, type II A. pleuropneumonia maternal antibody had lower level and positive rate and could not well protect piglets, so the various A. pleuropneumonia vaccines differed in the date for the first immunization. In order to achieve a better immunization effect, A. pleuropneumonia vaccines with different valences should be further researched and developed.