Despite the recent advances in avian influenza viruses surveillance and genomic data, fundamental questions concerning the ecology and evolution of these viruses remain elusive. In Egypt, H5N8 highly pathogenic avian influenza viruses (HPAIVs) are co-circulating simultaneously with HPAIVs of subtypes H5N1 and low-pathogenic avian influenza viruses (LPAIVs) of subtype H9N2 in both commercial and backyard poultry. In order to isolate AIVs from wild birds and to assess their potential in causing infection in commercial poultry, a total of thirty-four cloacal swab samples were collected from apparently healthy migratory wild birds (Anas acuta, Anas crecca, Rallus aquaticus, and Bubulcus ibis) from four Egyptian Governorates (Giza, Menoufia, Gharbia, and Dakahlia). Based on matrix (M) gene-targeting real-time reverse transcriptase PCR and subsequent genetic characterization, our results revealed two positive isolates (2/34) for H5N8 whereas no H5N1 and H9N2 subtypes were detected. Genetic characterization of the full-length haemagglutinin (HA) genes revealed the clustering of two reported isolates within genotype 5 of clade 2.3.4.4b. The potential of a wild bird-origin H5N8 virus isolated from a cattle egret for its transmission capability within and between chickens was investigated in compare to chicken origin H5N8 AIV. Chickens inoculated with cattle egret isolate showed varying clinical signs and detection of virus shedding. In contrast, the contact chickens showed less levels of virus secretion indicating efficient virus inter/intra-species transmission. These results demonstrated the possibility for spreading of wild bird origin H5N8 viruses between chicken. In conclusion, our study highlights the need for continuous and frequent monitoring of the genetic diversity of H5N8 AIVs in wild birds as well as commercial poultry sectors for better understanding and determining the genetic nature of these viruses, which is fundamental to predict any future threat through virus reassortment with the potential to threaten human and animal health. Likewise, an assessment of coverage and efficacy of different vaccines and or vaccination regimes in the field conditions should be reconsidered along with strict biosecurity measures.

尽管最近在禽流感病毒监测和基因组数据方面取得了进步，但有关这些病毒的生态学和进化的基本问题仍然难以捉摸。在埃及，H5N8高致病性禽流感病毒（HPAIV）与H5N1亚型的HPAIV和H9N2亚型的低致病性禽流感病毒（LPAIV）在商业和后院家禽中同时传播。为了从野禽中分离出禽流感病毒并评估其在商业家禽中引起感染的潜力，从看似健康的候鸟（阿纳斯acuta，阿纳斯crecca，Rallus aquaticus和Bubulcus ibis）中收集了总共34个泄殖腔拭子样本）来自四个埃及省（吉萨，梅诺菲亚，加尔比亚和达卡利亚）。基于靶向基质（M）基因的实时逆转录酶PCR和随后的遗传表征，我们的结果显示了H5N8的两个阳性分离株（2/34），而未检测到H5N1和H9N2亚型。全长血细胞凝集素（HA）基因的遗传特征揭示了进化枝2.3.4.4b的基因型5内两个报道的分离株的聚集。与源自鸡的H5N8 AIV相比，研究了从牛背鹭分离出野生禽源H5N8病毒在鸡内和鸡之间传播的潜力。接种牛背鹭分离株的鸡表现出不同的临床体征和病毒脱落的检测。相反，接触鸡的病毒分泌水平较低，表明病毒在种间/种内的有效传播。这些结果证明了在鸟类之间传播野禽来源的H5N8病毒的可能性。总而言之，我们的研究强调需要持续和频繁地监测野生鸟类以及商业家禽部门中H5N8 AIV的遗传多样性，以便更好地了解和确定这些病毒的遗传特性，这对于通过以下方式预测任何未来威胁至关重要病毒重组可能威胁人类和动物健康。同样，应重新考虑对野外条件下不同疫苗和/或疫苗接种方案的覆盖范围和功效的评估，以及严格的生物安全措施。这些结果证明了在鸟类之间传播野禽来源的H5N8病毒的可能性。总而言之，我们的研究强调需要持续和频繁地监测野生鸟类以及商业家禽部门中H5N8 AIV的遗传多样性，以便更好地了解和确定这些病毒的遗传特性，这对于通过以下方式预测任何未来威胁至关重要病毒重组可能威胁人类和动物健康。同样，应重新考虑对野外条件下不同疫苗和/或疫苗接种方案的覆盖范围和功效的评估，以及严格的生物安全措施。这些结果证明了在鸟类之间传播野禽来源的H5N8病毒的可能性。总而言之，我们的研究强调需要持续和频繁地监测野生鸟类以及商业家禽部门中H5N8 AIV的遗传多样性，以便更好地了解和确定这些病毒的遗传特性，这对于通过以下方式预测任何未来威胁至关重要病毒重组可能威胁人类和动物健康。同样，应重新考虑对野外条件下不同疫苗和/或疫苗接种方案的覆盖范围和功效的评估，以及严格的生物安全措施。我们的研究强调需要持续和频繁地监测野生鸟类以及商业家禽部门中H5N8 AIV的遗传多样性，以便更好地了解和确定这些病毒的遗传特性，这对于通过对病毒进行重新分类来预测未来的威胁至关重要威胁人类和动物健康的潜力。同样，应重新考虑对野外条件下不同疫苗和/或疫苗接种方案的覆盖范围和功效的评估，以及严格的生物安全措施。我们的研究强调需要持续和频繁地监测野生鸟类以及商业家禽部门中H5N8 AIV的遗传多样性，以便更好地了解和确定这些病毒的遗传特性，这对于通过对病毒进行重新分类来预测未来的威胁至关重要威胁人类和动物健康的潜力。同样，应重新考虑对野外条件下不同疫苗和/或疫苗接种方案的覆盖范围和功效的评估，以及严格的生物安全措施。