In this study, two highly pathogenic avian influenza (HPAI) H5N8 viruses were isolated from chicken and geese in 2018 and 2019 (Chicken/ME-2018 and Geese/Egypt/MG4/2019). The hemagglutinin and neuraminidase gene analyses revealed their close relatedness to the clade-2.3.4.4b H5N8 viruses isolated from Egypt and Eurasian countries. A monovalent inactivated oil-emulsion vaccine containing a reassortant virus with HA gene of the Chicken/ME-2018/H5N8 strain and a bivalent vaccine containing same reassortant virus plus a previously generated reassortant H5N1 strain (CK/Eg/RG-173CAL/17). The safety of both vaccines was evaluated in specific-pathogen-free (SPF) chickens. To evaluate the efficacy of the prepared vaccines, 2-week-old SPF chickens were vaccinated with 0.5 mL of a vaccine formula containing 10⁸/EID₅₀ /dose from each strain via the subcutaneous route. Vaccinated birds were challenged with either wild-type HPAI-H5N8 or H5N1 viruses separately at 3 weeks post-vaccine. Results revealed that both vaccines induced protective hemagglutination-inhibiting (HI) antibody titers as early as 2 weeks PV (≥5.0 log₂). Vaccinated birds were protected clinically against both subtypes (100 % protection). HPAI-H5N1 virus shedding was significantly reduced in birds that were vaccinated with the bivalent vaccine; meanwhile, HPAI-H5N8 virus shedding was completely neutralized in both tracheal and cloacal swabs after 3 days post-infection in birds that had been vaccinated with either vaccine. In conclusion, the developed bivalent vaccine proved to be efficient in protecting chickens clinically and reduced virus shedding via the respiratory and digestive tracts. The applicability of the multivalent avian influenza vaccines further supported their value to facilitate vaccination programs in endemic countries.

在这项研究中，在2018年和2019年从鸡和鹅中分离出了两种高致病性禽流感（HPAI）H5N8病毒（Chicken / ME-2018和Geese / Egypt / MG4 / 2019）。血凝素和神经氨酸酶基因分析显示它们与从埃及和欧亚国家分离的进化枝2.3.4.4b H5N8病毒密切相关。包含Chicken / ME-2018 / H5N8株具有HA基因的重配病毒的单价灭活油乳剂疫苗和包含相同重配病毒和先前生成的重配H5N1株的二价疫苗（CK / Eg / RG-173CAL / 17） 。两种疫苗的安全性均在无特定病原体（SPF）的鸡中进行了评估。为了评估所制备疫苗的功效，给2周大的SPF鸡接种0.5 mL含有10 ⁸ / EID的疫苗配方通过皮下途径从每个菌株₅₀ /剂量。在接种疫苗后的第3周，分别用野生型HPAI-H5N8或H5N1病毒攻击疫苗接种的鸟类。结果表明，两种疫苗均可在2周PV（≥5.0log ₂）之前诱导保护性血凝抑制（HI）抗体效价。）。接种疫苗的禽类在临床上受到保护，不能同时抵抗两种亚型（100％保护）。用二价疫苗接种的禽类中的HPAI-H5N1病毒脱落显着减少。同时，在接种了两种疫苗的禽类中，感染后3天后，气管和泄殖腔拭子中的HPAI-H5N8病毒脱落被完全中和。总之，开发出的二价疫苗被证明在临床上有效地保护了鸡，并减少了通过呼吸道和消化道的病毒脱落。多价禽流感疫苗的适用性进一步支持了其在流行国家促进疫苗接种计划的价值。