BACKGROUND Avian leukosis viruses (ALVs) are important contagious suppressive factors of chicken immunity and growth performance, resulted in enormous economic loss. Although virus eradication programs are applied in breeder flocks, ALVs are still widespread globally. Therefore, other valuable adjunct to reduce the negative effect of ALVs should be considered. Bursin-like peptide (BLP) showed remarkable immunomodulatory effects, whereas their influence on ALV-infected avian groups has not been reported. Here, a designed hybrid BLP was expressed in E. coli. The purified BLP was injected subcutaneously weekly in SPF chickens congenitally infected with a natural ALV strain. Then the influences of this BLP on the growth performance, immune response and virus titer of ALV-infected chickens were determined. RESULTS This BLP injection significantly improved the body weights of ALV-infected birds (P < 0.05). BLP injection significantly enhanced organ index in the BF in ALV-infected birds (P < 0.05). The weekly injection of BLP significantly lengthened the maintenance time of antibodies against Newcastle disease virus (NDV) attenuated vaccine of ALV-infected birds (P < 0.05) and boosted the antibody titer against avian influenza virus (AIV) H5 inactive vaccine of mock chicken (P < 0.05). BLP injection in mock chickens enhanced the levels of serum cytokines (IL-2, IL-4 and interferon-γ) (P < 0.05). Surprisingly, the novel BLP significantly inhibited expression of the ALV gp85 gene in the thymus (P < 0.05), kidney (P < 0.05) and bursa of Fabricius (BF) (P < 0.01) of ALV-infected chickens. Both viral RNA copy number and protein level decreased significantly with BLP (50 μg/mL) inoculation before ALV infection in DF1 cells (P < 0.05). CONCLUSIONS This is the first report investigating the influence of BLP on the growth and immunity performance of chickens infected by ALV. It also is the first report about the antiviral effect of BLP in vivo and in vitro. This BLP expressed in E. coli showed potential as a vaccine adjuvant, growth regulator and antiretroviral drug in chickens to decrease the negative effects of ALV infection.

中文翻译：

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一种新型Bursin样肽，可作为感染重组ALV的SPF鸡的潜在病毒抑制剂和免疫调节剂。

背景技术禽白血病病毒（ALV）是鸡免疫力和生长性能的重要传染性抑制因子，导致巨大的经济损失。尽管病毒消除计划已应用于种鸡群，但ALV在全球仍很普遍。因此，应考虑使用其他有价值的辅助手段来减少ALV的负面影响。类脂囊肽（BLP）表现出显着的免疫调节作用，而尚未报道它们对ALV感染禽类的影响。在这里，在大肠杆菌中表达了设计的杂交BLP。将纯化的BLP每周皮下注射到先天感染天然ALV株的SPF鸡中。然后确定了该BLP对ALV感染鸡的生长性能，免疫应答和病毒滴度的影响。结果本次注射BLP可以显着改善ALV感染禽的体重（P <0.05）。BLP注射显着增强了ALV感染禽类的高炉器官指数（P <0.05）。每周注射BLP显着延长了抗新城疫病毒（NDV）减毒ALV感染禽类疫苗的抗体的维持时间（P <0.05），并提高了针对模拟鸡的禽流感病毒（AIV）H5灭活疫苗的抗体效价（ P <0.05）。BLP注射在模拟鸡中可提高血清细胞因子（IL-2，IL-4和干扰素-γ）的水平（P <0.05）。令人惊讶的是，新型BLP显着抑制了ALV感染鸡的胸腺（P <0.05），肾脏（P <0.05）和法氏囊（BF）（P <0.01）中ALV gp85基因的表达。在DF1细胞中进行ALV感染之前，BLP（50μg/ mL）接种后，病毒RNA拷贝数和蛋白质水平均显着降低（P <0.05）。结论这是第一份研究BLP对被ALV感染的鸡的生长和免疫性能的影响的报告。这也是有关BLP在体内和体外抗病毒作用的首次报道。这种在大肠杆菌中表达的BLP在鸡中显示出作为疫苗佐剂，生长调节剂和抗逆转录病毒药物的潜力，可减少ALV感染的负面影响。这也是有关BLP在体内和体外抗病毒作用的首次报道。这种在大肠杆菌中表达的BLP在鸡中显示出作为疫苗佐剂，生长调节剂和抗逆转录病毒药物的潜力，可减少ALV感染的负面影响。这也是有关BLP在体内和体外抗病毒作用的首次报道。这种在大肠杆菌中表达的BLP在鸡中显示出作为疫苗佐剂，生长调节剂和抗逆转录病毒药物的潜力，可减少ALV感染的负面影响。