Weng Wenlian, Wang Hua, Ye Miaomiao, Hu Dongmei, Wu Jiajun, Qu Yajin, Gao Peng, Zhang Yongning, Zhou Lei, Ge Xinna, Guo Xin, Han Jun, Yang Hanchun
State Key Laboratory of Veterinary Public Health and Safety, Key Laboratory of Animal Epidemiology of the Ministry of Agriculture and Rural Affairs, China Agricultural University College of Veterinary Medicine, Beijing, China.
China Animal Disease Control Center, Beijing, China.
J Virol. 2025 Jul 22;99(7):e0058425. doi: 10.1128/jvi.00584-25. Epub 2025 May 30.
As a member of nucleocytoplasmic large DNA viruses, African swine fever virus (ASFV) has been proposed to include an intriguing nuclear stage for DNA replication. In this report, we revisited this early event by using the ASFV type II strain HN09 as a model organism. Our studies began with dissecting the early stages of the ASFV life cycle via analyses by viral growth kinetics, electron microscopy, and quantitative PCR (qPCR). We showed that the single replication cycle lasted about 9 h, with the initial early mRNA transcription taking place around 0.5 h upon virus incubation with host cells, a timing that is much earlier than previously found; the viral DNA replication occurred around 4-5 hours post-infection (hpi), coinciding with the formation of early viral factory (VF), followed by virion morphogenesis at 6-9 hpi. The time-course tracking of viral genomic and newly synthesized DNA via EdU (5-ethynyl-2-deoxyuridine) labeling and DNAscope hybridization combined with 3D reconstruction revealed that the viral DNA remained all the time in the cytoplasm. Further transcriptional studies by RNAscope targeting three early mRNAs (, , and ) and EU labeling of nascent viral RNAs revealed similar results regarding their localization. In line with these observations, disruption of the nucleocytoplasmic shuttling with either small interfering RNA (siRNA) or chemical inhibitor did not affect ASFV replication. In contrast, the replication of porcine pseudorabies virus (PRV) was significantly reduced. Thus, we provide strong evidence to suggest that ASFV DNA replication does not involve a nuclear stage. Our findings provide great insight into the replication biology of ASFV.IMPORTANCEAfrican swine fever virus (ASFV) represents a devastating threat to the global swine industry. This virus has a large genomic size of 170 to 200 kb with a complex virion structure, but how this virus coordinates transcription/replication cascades has remained poorly defined. By using modern techniques, including EdU (5-ethynyl-2-deoxyuridine) and EU labeling, DNAscope and RNAscope, 3D reconstruction, and RNA interference (RNAi), we provide compelling evidence to show that the ASFV life cycle does not involve a nuclear stage, with both viral transcription and DNA replication confined to the cell cytoplasm. Our findings provide important insight into ASFV replication biology and into seeking targets for antiviral drug development.
作为核质大DNA病毒的一员,非洲猪瘟病毒(ASFV)被认为在DNA复制过程中存在一个有趣的核阶段。在本报告中,我们以ASFV II型毒株HN09作为模式生物,重新审视了这一早期事件。我们的研究始于通过病毒生长动力学、电子显微镜和定量PCR(qPCR)分析来剖析ASFV生命周期的早期阶段。我们发现,单个复制周期持续约9小时,病毒与宿主细胞孵育后约0.5小时开始初始早期mRNA转录,这一时间比之前发现的要早得多;病毒DNA复制在感染后4 - 5小时发生,与早期病毒工厂(VF)的形成同时出现,随后在感染后6 - 9小时进行病毒粒子形态发生。通过EdU(5 - 乙炔基 - 2 - 脱氧尿苷)标记和DNAscope杂交结合3D重建对病毒基因组和新合成DNA进行时间进程追踪,结果显示病毒DNA始终保留在细胞质中。通过针对三种早期mRNA(、和)的RNAscope以及新生病毒RNA的EU标记进行的进一步转录研究,在其定位方面也得出了类似结果。与这些观察结果一致,使用小干扰RNA(siRNA)或化学抑制剂破坏核质穿梭并不影响ASFV复制。相比之下,猪伪狂犬病病毒(PRV)的复制则显著减少。因此,我们提供了有力证据表明ASFV DNA复制不涉及核阶段。我们的研究结果为深入了解ASFV的复制生物学提供了重要线索。
重要性
非洲猪瘟病毒(ASFV)对全球养猪业构成了毁灭性威胁。这种病毒基因组庞大,大小为170至两百kb,病毒粒子结构复杂,但该病毒如何协调转录/复制级联反应仍不清楚。通过使用现代技术,包括EdU(5 - 乙炔基 - 2 - 脱氧尿苷)和EU标记、DNAscope和RNAscope、3D重建以及RNA干扰(RNAi),我们提供了令人信服的证据表明,ASFV生命周期不涉及核阶段,病毒转录和DNA复制均局限于细胞质中。我们的研究结果为深入了解ASFV复制生物学以及寻找抗病毒药物开发靶点提供了重要线索。