Gupta Ashish, Ahmed Khawaja Ashfaque, Ayalew Lisanework E, Popowich Shelly, Kurukulasuriya Shanika, Goonewardene Kalhari, Gunawardana Thushari, Karunarathna Ruwani, Ojkic Davor, Tikoo Suresh K, Willson Philip, Gomis Susantha
Department of Veterinary Pathology, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
Animal Health Laboratory, Laboratory Services Division, University of Guelph, Guelph, Ontario, Canada.
Vaccine. 2017 May 9;35(20):2716-2722. doi: 10.1016/j.vaccine.2017.03.075. Epub 2017 Apr 7.
Inclusion body hepatitis (IBH) is an economically important diseases in broiler chicken industry. Several serotypes of fowl adenovirus (FAdV) can cause IBH, among them, serotype FAdV-8b is associated with the majority of the IBH cases in Canada. Here, we evaluated FAdV-8b virus-like particles (VLPs) and recombinant FAdV-8b fiber proteins (expressed in E. coli) as potential broiler-breeder vaccines against IBH. For assessing the immunogenicity of vaccines, we investigated both humoral and cellular immunity. The humoral immune response was evaluated by determining total IgY and virus-neutralizing antibody in serum at 14, 28, 35 and 60days post-immunization (dpi). We examined cellular immunity using flow cytometry by determining CD4:CD8 ratio change in peripheral blood after the booster vaccination. The protective effect of vaccines was tested by challenging 14day-old progeny (n=30/group) carrying maternal antibodies (MtAb) by challenging with virulent FAdV-8b virus (1×10 TCID, FAdV-8b-SK). Although total IgY levels were comparable in all groups, the neutralizing antibody response in broiler-breeders at 35 and 60 dpi was significantly (p<0.05) higher those vaccinated with FAdV-8b VLPs followed by FAdV-8b fiber compared to fiber-knob. Moreover, vaccines comprised of FAdV-8b VLPs and FAdV-8b fiber rather than FAdV-8b fiber-knob efficiently elicited the cell-mediated immune response as evidenced by a statistically significant (p<0.05) CD8 T-cell proliferative response in broiler-breeders four days after the booster vaccination. Unlike FAdV-8b fiber-knob, FAdV-8b VLPs, and FAdV-8b fiber vaccinated broiler-breeders were able to transfer a substantial amount (28.4±9%) of MtAb to their progeny. Challenge revealed that MtAb provided 100% and 82.7% protection in progeny hatched from FAdV-8b VLPs, and FAdV-8b fiber vaccinated broiler-breeders, respectively. Collectively, our data suggest that FAdV-8b subunit vaccine-induced MtAb efficiently protected progeny against clinical IBH and broiler-breeder vaccination with subunit vaccines is a potential approach to protect against IBH.
包涵体肝炎（IBH）是肉鸡养殖业中一种具有重要经济影响的疾病。几种禽腺病毒（FAdV）血清型可引起IBH，其中，FAdV - 8b血清型与加拿大大多数IBH病例相关。在此，我们评估了FAdV - 8b病毒样颗粒（VLPs）和重组FAdV - 8b纤维蛋白（在大肠杆菌中表达）作为预防IBH的潜在种鸡疫苗。为评估疫苗的免疫原性，我们同时研究了体液免疫和细胞免疫。通过测定免疫后14、28、35和60天血清中的总IgY和病毒中和抗体来评估体液免疫反应。我们通过流式细胞术检测加强免疫后外周血中CD4:CD8比值的变化来检查细胞免疫。通过用强毒FAdV - 8b病毒（1×10 TCID，FAdV - 8b - SK）攻击携带母源抗体（MtAb）的14日龄后代（每组n = 30）来测试疫苗的保护效果。尽管所有组的总IgY水平相当，但与接种FAdV - 8b纤维瘤蛋白相比，接种FAdV - 8b VLPs后再接种FAdV - 8b纤维蛋白的种鸡在35和60 dpi时的中和抗体反应显著（p<0.05）更高。此外，由FAdV - 8b VLPs和FAdV - 8b纤维组成的疫苗比FAdV - 8b纤维瘤蛋白更有效地引发细胞介导的免疫反应，加强免疫四天后种鸡中CD8 T细胞增殖反应具有统计学意义（p<0.05）证明了这一点。与FAdV - 8b纤维瘤蛋白不同，接种FAdV - 8b VLPs和FAdV - 8b纤维的种鸡能够将大量（28.4±9%）的MtAb传递给它们的后代。攻毒试验表明，MtAb分别为接种FAdV - 8b VLPs和FAdV - 8b纤维的种鸡所孵出的后代提供了100%和82.7%的保护。总体而言，我们的数据表明，FAdV - 8b亚单位疫苗诱导的MtAb能有效保护后代免受临床IBH感染，种鸡接种亚单位疫苗是预防IBH的一种潜在方法。
