Department of Animal Science and Technology, Shandong Agricultural University, 61 Daizong Road, Tai'an 271018, PR China.
Agricultural College of Liaocheng University, 1 Hunan Road, Liaocheng 252059, PR China.
Poult Sci. 2018 Mar 1;97(3):803-811. doi: 10.3382/ps/pex338.
An outbreak of hydropericardium syndrome has been ongoing in East China since 2015. To decipher the disease etiology, 26 full-length sequences of the adenovirus hexon gene were cloned and sequenced. Phylogenetic trees and sequence alignments revealed that all 26 strains belonged to subgroup C serotype 4 and shared some consistent molecular characteristics that showed only 9 mutations without amino acid (AA) deletions. Eight sites were located in L1 and one in L2. To determine whether the complete hexon gene was under positive selection pressure, site-by-site analysis was performed to identify specific codons that underwent evolutionary selection. Analysis identified 7 positively selected codons in L1 (AA 164, 168, 195, and 243) and L2 (AA 379, 402, and 408). The other 2 sites (AA 140 and 680) were located in P1 and P2, respectively. The results reveal that hexon loops L1 and L2 are hypervariable regions. Moreover, elucidation of viral distribution indicated that the liver is a major target organ, and FAdV-4 is a pantropic virus. In summary, FAdV-4 has been identified as an epidemic strain, and viral evolution is ongoing; thus, continuous surveillance of this virus will contribute to the control of future epidemics.
自 2015 年以来，华东地区一直爆发包涵体肝炎综合征。为了解剖疾病病因，克隆并测序了 26 株腺病毒六邻体基因的全长序列。系统进化树和序列比对显示，所有 26 株病毒均属于血清型 4 亚群 C，具有一些一致的分子特征，仅 9 个突变无氨基酸缺失。8 个位点位于 L1 区，1 个位于 L2 区。为确定完整的六邻体基因是否受到正选择压力，对各位点进行了逐个分析，以确定经历进化选择的特定密码子。分析鉴定了 L1（AA164、168、195 和 243）和 L2（AA379、402 和 408）区的 7 个正选择密码子。另外 2 个位点（AA140 和 680）分别位于 P1 和 P2 区。结果表明，六邻体环 L1 和 L2 是高变区。此外，病毒分布的阐明表明肝脏是主要靶器官，且 FAdV-4 是一种泛嗜性病毒。总之，FAdV-4 已被鉴定为流行株，病毒进化仍在继续；因此，对该病毒的持续监测有助于控制未来的流行。
