Department of Poultry Diseases, Animal Health Research Institute (Zagazig Branch), Zagazig, Sharkia, 44511 Egypt.
Department of Avian and Rabbit Medicine, Faculty of Veterinary Medicine, Zagazig University, Zagazig, Sharkia, 44511 Egypt.
Avian Dis. 2020 Sep 1;64(3):269-276. doi: 10.1637/aviandiseases-D-19-00158.
Duck hepatitis A viruses (DHAV-1, DHAV-2, and DHAV-3) are the predominant causes of duck virus hepatitis (DVH), a disease of ducklings that leads to massive morbidities, mortalities, and economic losses. As a duck-producing country, Egypt suffered lately from several attacks of DVH, despite the regular vaccination of birds. Between Spring 2016 and Summer 2018, 54 duckling flocks in the Sharkia province of Egypt were tested using the reverse-transcription PCR (RT-PCR) based on the DHAV-3D targeting primers. Of them, 27.8% (15/54) were positive. Upon retesting of positive samples using RT-PCR and duck hepatitis A virus (DHAV)-3 VP1-based primers, 33.3% (5/15) contained DHAV-3 RNA. For further analysis at the molecular level, the VP1 and the 3D genes were sequenced using the same primer sets used earlier. The phylogenetic trees confirmed that study sequences belonged to DHAV-3. However, they were displayed as a separate cluster following a geographically dependent distribution. They were also completely unrelated to the Egyptian DHAV-1-based vaccine. This was further confirmed by low nucleotide and amino acid identities in relation to this vaccine. In addition, the VP1 and 3D genes had the same phylogenetic topography. The study VP1 sequences had three unique amino acid substitutions (L59, V208 only in one strain, and C219). As far as we know, this is the first report on DHAV-3 outside Asia, particularly in Egypt. Accordingly, the vaccination strategy against DHAV should be quickly updated to avoid further dissemination of the virus. The epidemiology, pathogenicity, and evolution of DHAV-3 should be carefully monitored in Egypt.
鸭甲型肝炎病毒（DHAV-1、DHAV-2 和 DHAV-3）是鸭病毒性肝炎（DVH）的主要病原体，该病是一种雏鸭疾病，可导致大量发病、死亡和经济损失。埃及作为一个养鸭大国，尽管对禽类进行了常规疫苗接种，但最近仍多次遭受 DVH 的侵袭。在 2016 年春季至 2018 年夏季期间，对埃及 Sharkia 省的 54 个雏鸭群使用基于 DHAV-3D 靶向引物的逆转录 PCR（RT-PCR）进行了检测。其中，27.8%（15/54）为阳性。对阳性样本使用 RT-PCR 和鸭肝炎 A 病毒（DHAV）-3 VP1 基引物进行复测后，33.3%（5/15）含有 DHAV-3 RNA。为了在分子水平上进行进一步分析，使用先前使用的相同引物对 VP1 和 3D 基因进行了测序。系统进化树证实，研究序列属于 DHAV-3。然而，它们按照地理位置相关的分布方式显示为一个单独的聚类。它们与埃及基于 DHAV-1 的疫苗也完全没有关系。这进一步通过与该疫苗的低核苷酸和氨基酸同一性得到证实。此外，VP1 和 3D 基因具有相同的系统进化拓扑结构。研究的 VP1 序列有三个独特的氨基酸取代（L59、V208 仅在一个菌株中，C219）。据我们所知，这是 DHAV-3 在亚洲以外，特别是在埃及的首次报告。因此，应迅速更新针对 DHAV 的疫苗接种策略，以避免病毒进一步传播。应在埃及密切监测 DHAV-3 的流行病学、致病性和进化。
