禽脑脊髓炎弱毒疫苗不同免疫期的种鸡及其后裔雏鸡母源抗体的衰减规律

艾维茵父母代肉种鸡经禽脑脊髓炎病毒(AEV)弱毒疫苗免疫后,用琼脂扩散试验对不同免疫期种鸡的后裔雏鸡的母源抗体进行动态监测。结果发现,26周龄种鸡禽脑脊髓炎(AE)抗体阳性率为86.7%～100%,其后裔雏鸡在1～7日龄时母源抗体阳性率为83.3%～100%;14日龄时降至30.0%～70.0%;多数在21日龄时转阴。36周龄种鸡AE抗体阳性率为56.7%～76.7%,其后裔雏鸡在1日龄时母源抗体阳性率只有50.0%～76.7%;7日龄时降至10.0%～50.0%;14日龄时全部转阴。表明,雏鸡AE母源抗体水平及其衰减规律受种鸡抗体水平的影响。攻毒保护试验发现,低母源抗体雏鸡(1日龄母源抗体阳性率为50.0%),不但7～28日龄脑内攻毒后6～11d全部发病,而且14日龄颈部皮下攻毒后11～13d也有6/10雏鸡发病;而高母源抗体雏鸡(1日龄的母源抗体为100%),虽然14～28日龄对脑内攻毒易感,但是颈部皮下攻毒后观察45d均未发病。证实,雏鸡1日龄的AE母源抗体为50.0%时,很难保护其免受AEV的侵袭。

Attenuation of maternal antibody against avian encephalomyelitis virus and protective effects in progeny chickens

The maternal antibodies against AEV of chickens were detected dynamically with agar-gel-precipition (AGP) test. The AGP-~positive sate of the progeny chickens from breeder flocks with AGP-~positive 100%-86.7% was 100%-83.3% at one day of age, and decreased to 70%-30% at 14 days of age, most samples converted serological negative at 21 days of age. However, AGP-positive percentage of the progeny chickens from breeder flocks with AGP-positive 76.7%-56.7% was 73.3%-50.0% at one day of age, and decreased to 50%-10% at 7 days of age, most samples converted negative at 14 days of age. The results showed that there was a relationship between the maternal antibody level in the progeny ~chickens and the antibody level of breeder flocks. AE occurred after AEV subcutaneous challenge in some of ~chickens with 50% positive maternal antibody at one-day-age.