Institute of Hydrobiology, The Innovation Academy of Seed Design, Chinese Academy of Sciences, Wuhan 430072, China.
College of Modern Agriculture Sciences, University of Chinese Academy of Sciences, Beijing 100049, China.
Viruses. 2022 Apr 27;14(5):908. doi: 10.3390/v14050908.
The ranavirus (ADRV) is a member of the family and belongs to the nucleocytoplasmic large DNA viruses. Based on genomic analysis, an ADRV-encoding protein, ADRV , and its homologs from other iridoviruses were predicted as Rad2 family proteins based on the conserved amino acids, domains, and secondary structures. Expression analysis showed that the transcription of ADRV started at 4 h post infection, and its expression was not inhibited by a DNA-replication inhibitor. Meanwhile, immunofluorescence localization showed that ADRV mainly localized in viral factories and colocalized with the viral nascent DNA, which hinted at a possible role in DNA replication. Furthermore, a mutant ADRV lacking (ADRV-Δ12L) was constructed. In both luciferase assays based on homologous recombination (HR) and double-strand break repair (DSBR) that followed, ADRV-Δ12L induced less luciferase activity than the wild-type ADRV, indicating that HR and DSBR were impaired in ADRV-Δ12L infected cells. In addition, infection with ADRV-Δ12L resulted in smaller plaque sizes and lower viral titers than that with wild-type ADRV, indicating an important role for in efficient virus infection. Therefore, the results suggest that Rad2 homologs encoded by iridovirus have important roles in HR- and DSBR-process of the viral DNA and, thus, affect virus replication and the production of progeny virions.
蛙病毒（ADRV）是虹彩病毒科的一员，属于核质大 DNA 病毒。基于基因组分析，ADRV 编码的一种蛋白 ADRV 和其他虹彩病毒的同源物被预测为 Rad2 家族蛋白，这是基于保守的氨基酸、结构域和二级结构。表达分析表明，ADRV 的转录始于感染后 4 小时，其表达不受 DNA 复制抑制剂的抑制。同时，免疫荧光定位显示 ADRV 主要定位于病毒工厂，与病毒新生 DNA 共定位，这暗示了其在 DNA 复制中的可能作用。此外，构建了缺失 的 ADRV 突变体（ADRV-Δ12L）。在随后的基于同源重组（HR）和双链断裂修复（DSBR）的荧光素酶检测中，ADRV-Δ12L 诱导的荧光素酶活性低于野生型 ADRV，表明 HR 和 DSBR 在 ADRV-Δ12L 感染的细胞中受到损害。此外，与野生型 ADRV 相比，ADRV-Δ12L 的感染导致更小的噬菌斑大小和更低的病毒滴度，表明 在有效的病毒感染中起着重要作用。因此，结果表明虹彩病毒编码的 Rad2 同源物在病毒 DNA 的 HR 和 DSBR 过程中具有重要作用，从而影响病毒复制和产生子代病毒颗粒。
