African swine fever (ASF), caused by the ASF virus (ASFV), is a hemorrhagic and fatal viral disease that affects Eurasian wild boars and domestic pigs, posing a substantial threat to the global pig breeding industry. ASFV, a double-stranded DNA virus, possesses a large genome containing up to 160 open reading frames, most of which exhibit unknown functions. The B125R gene of ASFV, located at the 105595–105972 bp site in the ASFV-SY18 genome, remains unexplored. In this study, we discovered that deletion did not affect recombinant virus rescue, nor did it hinder viral replication during the intermediate growth phase. Although the virulence of the recombinant strain harboring this deletion was attenuated, intramuscular inoculation of the recombinant virus in pigs at doses of 10 or 10 TCID resulted in mortality. Moreover, sequencing analysis of six recombinant strains obtained from three independent experiments consistently revealed an adenine insertion at the 47367–47375 bp site in the A104R gene due to the B125R deletion, leading to premature termination of this gene. Intriguingly, this insertion did not influence the transcription of the A104R gene between the recombinant and parental strains. Consequently, we postulate that the deletion of the B125R gene in ASFV-SY18 or other genotype II strains may marginally attenuate virulence in domestic pigs.

中文翻译：

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非洲猪瘟病毒 SY18 株中 B125R 基因的缺失导致 A104R 移码突变，略微减弱对家猪的毒力

非洲猪瘟（ASF）是由非洲猪瘟病毒（ASFV）引起的一种出血性、致命性病毒性疾病，影响欧亚野猪和家猪，对全球生猪养殖业构成重大威胁。 ASFV 是一种双链 DNA 病毒，拥有庞大的基因组，包含多达 160 个开放阅读框，其中大部分表现出未知的功能。 ASFV 的 B125R 基因位于 ASFV-SY18 基因组中的 105595-105972 bp 位点，仍未被探索。在这项研究中，我们发现缺失并不影响重组病毒的拯救，也不会阻碍病毒在中间生长期的复制。尽管含有该缺失的重组病毒株的毒力减弱，但以10或10 TCID的剂量将重组病毒肌肉注射到猪体内会导致死亡。此外，对三个独立实验获得的六种重组菌株的测序分析一致表明，由于 B125R 缺失，A104R 基因的 47367-47375 bp 位点出现腺嘌呤插入，导致该基因过早终止。有趣的是，这种插入并不影响重组菌株和亲本菌株之间 A104R 基因的转录。因此，我们假设 ASFV-SY18 或其他基因型 II 毒株中 B125R 基因的缺失可能会略微减弱在家猪中的毒力。