Abaza M A, Elboraay E M, Saad A E, Zayan K A
Avian and Rabbit Diseases Department, Faculty of Veterinary Medicine, Benha University, Kaliobyia, Egypt.
Avian Pathol. 2020 Dec;49(6):581-588. doi: 10.1080/03079457.2020.1796925. Epub 2020 Aug 10.
Infectious bursal disease (IBD) remains a potential worldwide threat to the poultry industry despite several vaccination approaches. Because maternally derived antibodies (MDA) constitute a critical problem for IBD vaccination, we examined the efficiency of the intracloacal vaccination approach in breaking through MDA. Experiment 1 determined the ability of the vaccinal strain to multiply in the bursa of Fabricius (BF) in chicks with a high level of MDA. Using real-time polymerase chain reaction, we quantified the strain in the bursae of vaccinated and non-vaccinated chicks. Experiment 2 was performed on three groups of chicks with high levels of MDA: group 1, non-vaccinated non-challenged; group 2, non-vaccinated challenged; and group 3, vaccinated challenged. Seroconversion to IBDV was measured using enzyme-linked immunosorbent assay. Groups 2 and 3 were challenged by vvIBDV at 25 days of age. Experiment 3 studied the effect of early IBD vaccinal strain multiplication on the immune response of vaccinated and non-vaccinated chicks to other vaccines. In experiment 1, the vaccinal strain showed progressive multiplication and reached the detectable titre in BF at 12 h post-vaccination despite high MDA titre. Experiment 2 showed that chicks in group 3 had significant seroconversion against IBDV. After challenge, group 3 showed significant improvements in several measured parameters compared with group 2. Moreover, results of experiment 3 proved that early multiplication of the vaccinal strain in the BF has no significant effect on the immune system or immune response to other vaccines. These results proved the promising success of this IBD vaccination approach. IBD vaccinal strain succeeded in multiplying in BF after intracloacal inoculation.Vaccinated chicks showed significant seroconversion of IBDV antibody titres.Vaccinated chicks showed a significant protection level against vvIBDV.Early IBD vaccination did not affect the immune response to other vaccines.
尽管有多种疫苗接种方法，但传染性法氏囊病（IBD）仍然是全球家禽业面临的潜在威胁。由于母源抗体（MDA）对IBD疫苗接种构成关键问题，我们研究了经泄殖腔接种疫苗方法突破MDA的效果。实验1确定了疫苗毒株在具有高水平MDA的雏鸡法氏囊中增殖的能力。使用实时聚合酶链反应，我们对接种和未接种雏鸡的法氏囊中该毒株进行了定量。实验2在三组具有高水平MDA的雏鸡上进行：第1组，未接种且未攻毒；第2组，未接种但攻毒；第3组，接种且攻毒。使用酶联免疫吸附测定法检测针对传染性法氏囊病病毒（IBDV）的血清转化。第2组和第3组在25日龄时用超强毒IBDV攻毒。实验3研究了早期IBD疫苗毒株增殖对接种和未接种雏鸡对其他疫苗免疫反应的影响。在实验1中，尽管MDA滴度很高，但疫苗毒株仍显示出逐渐增殖，并在接种后12小时在法氏囊中达到可检测滴度。实验2表明，第3组雏鸡对IBDV有显著的血清转化。攻毒后，与第2组相比，第3组在几个测量参数上有显著改善。此外，实验3的结果证明，疫苗毒株在法氏囊中早期增殖对免疫系统或对其他疫苗的免疫反应没有显著影响。这些结果证明了这种IBD疫苗接种方法取得了有希望的成功。IBD疫苗毒株经泄殖腔接种后成功在法氏囊中增殖。接种疫苗的雏鸡显示出IBDV抗体滴度的显著血清转化。接种疫苗的雏鸡对超强毒IBDV显示出显著的保护水平。早期IBD疫苗接种不影响对其他疫苗的免疫反应。
