College of Life Science, Shandong Agricultural University, Taian, Shandong, China.
Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Shandong Agricultural University, Taian, Shandong, China.
Transbound Emerg Dis. 2021 Mar;68(2):267-275. doi: 10.1111/tbed.13708. Epub 2020 Jul 11.
Duck hepatitis A virus (DHAV) causes a highly contagious and acute disease in ducklings younger than 3 weeks of age and spreads rapidly by horizontal transmission to all susceptible ducklings in the flock. To date, there is no evidence of vertical transmission of DHAV-1. In a previous study, we identified a novel DHAV type 1 (DHAV-1) isolate that could infect adult ducks and induce laying drop. In this study, 30 non-embryonated duck eggs and 60 17-day-old embryos were collected from three breeding duck flocks with egg drop syndrome caused by DHAV-1 in China, and 30 17-day-old embryos were randomly selected from the 60 embryos and allowed to hatch. DHAV-1 RNA was detected by RT-PCR in 10 of 30 non-embryonated eggs, 9 of 30 17-day-old embryos, 5 of 7 dead embryos and 5 of 23 newly hatched ducklings. Overall, 29 of 90 (32.2%) eggs and embryos were positive for DHAV-1. Three DHAV-1 strains were isolated from the dead duck embryos of the three breeding duck flocks, respectively. Pathogenicity studies showed that the three DHAV-1 isolates had median embryo lethal doses but were highly pathogenic to healthy ducklings. Compared with the DHAV reference strains, there were two specific amino acid mutation sites (F and S ) in VP1 of the three isolates. To the best of our knowledge, this is the first report that DHAV-1 is isolated from duck embryos. The findings provide evidence of possible vertical transmission of DHAV-1 from breeding ducks to ducklings.
鸭甲型肝炎病毒 (DHAV) 可引起 3 周龄以下雏鸭高度传染性和急性疾病，并通过水平传播迅速传播至群体中所有易感雏鸭。迄今为止，尚无 DHAV-1 垂直传播的证据。在之前的研究中，我们鉴定了一种新型的 DHAV 1 型 (DHAV-1) 分离株，它可以感染成年鸭并引起产蛋量下降。在这项研究中，我们从中国三个因 DHAV-1 引起产蛋下降综合征的种鸭群中收集了 30 枚未受精鸭蛋和 60 枚 17 日龄胚胎，从 60 枚胚胎中随机选择了 30 枚 17 日龄胚胎进行孵化。通过 RT-PCR 在 30 枚未受精鸭蛋中的 10 枚、30 枚 17 日龄胚胎中的 9 枚、7 枚死胚中的 5 枚和 23 只新孵化的雏鸭中的 5 枚中检测到 DHAV-1 RNA。总体而言，90 个（32.2%）卵和胚胎中 DHAV-1 阳性。从三个种鸭群的死鸭胚胎中分别分离到三个 DHAV-1 株。致病性研究表明，这三个 DHAV-1 分离株具有中等胚胎致死剂量，但对健康雏鸭高度致病。与 DHAV 参考株相比，这三个分离株的 VP1 中有两个特定的氨基酸突变位点（F 和 S）。据我们所知，这是首次报道 DHAV-1 从鸭胚中分离出来。这些发现为 DHAV-1 从种鸭垂直传播到雏鸭提供了证据。
