| The purpose of this study is to get a reasonable, scientific immunity procedure of CSF which is suitable for the large-scaled pig farm. A commercial blocking antibody ELIS A Kits was employed to detect the titer of antibody against classical swine fever virus (CSFV), by which the influence of the quantity of vaccine on the level of antibody, the relation between the level of piglets’maternal derived antibody(MDA) and pregnant sows, the dynamic change of piglets’MDA, the affect of MDA on antibody of piglets trigered by vaccine and the the dynamic change of antibody level in sow were investigated.Several commercial cell original CSF vaccines were chosen to immunize pre-tests herds for analyses of the antiboy titer in sera and effect of protection agaist CSFV infection, and the results revealed that the antibody (MDA) response and level of antibody titer for each vaccine which from various companies are different obviously. Finally, a vaccine from a Guangdong producer was set as a reference vaccine in this study for its best protection against CSFV infection. As the results showed, single vaccination with this vaccine in two different dose (106TCID50and105TCIDso) can provide the piglets a complete protection against challenge with strong virulent CSFV strain in a lethal dose (1x104TCID50)The antibody titers of different herds were obsevered to analysis the differences among pregnant sows, lactating sows, boars and replacement breeding pigs, and results indicated that pregnant sows got the highest score with91.71%in antibody positive rate and74.67%±22.22in blocking rate. The titer and duration of piglets’ MDA were directly related to the antiboy titer of sows, as results showed the higher level of antibody in sows, the higher antibody titer, the slower declease rate, and longer duration in piglets; otherwise contrast completely.Ten serials of immunity procedure were conducted to estimate the merits of the immunity procedure, and it was demonstrated that piglets vaccinated twice on35d and70d was the best procedure. Piglets with various level of MDA titer were divided into different groups and vaccinated to observe the influence of MDA on vaccination in piglets. It was found that the effect of inmmunity was seriously disturbed by MDA after the fisrt vaccination both in antibody titer and positive rate, resulting a contrary effect, same in the second vaccination.In order to evaluate the duration of antibody in sows, the change dynamic of antibody titer was obersevered among sows with different level antibody. It was found that the antibody titer was not decreased any more in sows with high level antibody (above80%in blocking rate), comparely it was obviousely in sows with70-80%. Inaddtionally, sows, which antiboy level under70%, were conducted a second inmmunity to investigate its effect to improve antiboy level. Intersetingly, the positive was obviously in sows which antibody level was under50%, while less in those above this level.According to the results above, we can get a conclusion:the quantity of CSFV vaccine is critial to the antibody level and effective protection; the level of MDA in piglets is depended on the antibody titer of sows, however it presented a negative infact on the effect of vaccine on piglets inmmunity; there is a direct relation between antibody duration and level in sows, and secondary vaccination can improve antibody titer of sows which present a low level. Thus, it is very important to investigate the antibody titer of sows in modern, large-scaled pig farm, which is dispensible for producing a reasonable, scientific immunity procedure to provent CSF. |
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