Dybing J K, Jackwood D J
Department of Veterinary Preventive Medicine, Ohio Agricultural Reseach and Development Center, Ohio State University, Wooster 44691, USA.
Avian Dis. 1998 Jan-Mar;42(1):80-91.
Genomic segment A of the variant Md infectious bursal disease virus (IBDV) was amplified by reverse transcriptase/polymerase chain reaction, cloned, and expressed in the baculovirus expression system. Three different baculovirus recombinants expressing the genes encoding VP2, VP2/VP4, and the complete polyprotein (VP2/VP4/VP3) were prepared. The three antigens were used in separate enzyme-linked immunosorbent assays, and each detected antibodies against the variant IBDV strains Md, Del-A, Del-E, and GLS and the classic IBDV strain D78 throughout a 14-wk period following vaccination. Eight-week-old specific-pathogen-free (SPF) chickens were inoculated subcutaneously using the VP2/VP4 or VP2/VP4/VP3 baculovirus recombinant or wild-type baculovirus-infected insect cell lysates. Virus-neutralizing antibodies were detected in the VP2/VP4 and VP2/VP4/VP3 baculovirus-inoculated birds at 13 days postinoculation (PI) and at 43 days PI when titrated against Md IBDV. No virus-neutralizing antibody titer was observed in the negative controls or wild-type baculovirus-inoculated birds. One-week-old SPF chickens were inoculated with the VP2, VP2/VP4/VP3 baculovirus recombinants or wild-type baculovirus-infected insect cell lysates. The birds were boosted 2 wk later and challenged at 4 wk of age with 0.5 ml/bird classic STC IBDV (10(2) median embryo infective dose [EID50]/ml) or variant Md IBDV (10(5) EID50/ml) via the oral/nasal route. The VP2 and VP2/VP4/VP3 baculovirus-inoculated birds were partially protected against challenge with the classic STC IBDV. The birds were protected against clinical disease and death but not bursal damage, whereas the wild-type baculovirus-inoculated birds exhibited clinical signs of disease, 13% mortality, and bursal damage. When challenged with the variant Md IBDV, neither the VP2, VP2/VP4/VP3 baculovirus recombinants nor the wild-type baculovirus elicited protection against bursal damage and atrophy.
通过逆转录酶/聚合酶链反应扩增变异型传染性法氏囊病病毒（IBDV）Md株的基因组A片段，进行克隆，并在杆状病毒表达系统中表达。制备了三种表达编码VP2、VP2/VP4和完整多聚蛋白（VP2/VP4/VP3）基因的不同杆状病毒重组体。将这三种抗原分别用于酶联免疫吸附测定，在接种疫苗后的14周内，每种抗原均能检测到针对变异型IBDV毒株Md、Del - A、Del - E和GLS以及经典IBDV毒株D78的抗体。用VP2/VP4或VP2/VP4/VP3杆状病毒重组体或野生型杆状病毒感染的昆虫细胞裂解物皮下接种8周龄的无特定病原体（SPF）鸡。在接种后13天（PI）和43天PI时，用Md IBDV进行滴定，在接种VP2/VP4和VP2/VP4/VP3杆状病毒的鸡中检测到病毒中和抗体。在阴性对照或接种野生型杆状病毒的鸡中未观察到病毒中和抗体滴度。用VP2、VP2/VP4/VP3杆状病毒重组体或野生型杆状病毒感染的昆虫细胞裂解物接种1周龄的SPF鸡。2周后对鸡进行加强免疫，并在4周龄时通过口服/鼻内途径用0.5 ml/只经典STC IBDV（10²半数胚胎感染剂量[EID50]/ml）或变异型Md IBDV（10⁵ EID50/ml）进行攻毒。接种VP2和VP2/VP4/VP3杆状病毒的鸡对经典STC IBDV攻毒有部分保护作用。这些鸡可免受临床疾病和死亡，但不能免受法氏囊损伤，而接种野生型杆状病毒的鸡表现出疾病的临床症状、13%的死亡率和法氏囊损伤。当用变异型Md IBDV攻毒时，VP2、VP2/VP4/VP3杆状病毒重组体和野生型杆状病毒均未引发对法氏囊损伤和萎缩的保护作用。
