Xu Sijia, Liu Jing, Xing Jiabao, Gao Han, Zhu Dihua, Xu Zhiying, Zhong Jianhao, Li Yue, Gao Xiaopeng, Kuang Qiyuan, Zhang Guihong, Wang Heng, Sun Yankuo
Key Laboratory of Zoonosis Prevention and Control of Guangdong Province, College of Veterinary Medicine, South China Agricultural University, Guangzhou, China.
National Engineering Research Center for Breeding Swine Industry, South China Agricultural University, Guangzhou, China.
Transbound Emerg Dis. 2023 Nov 16;2023:3869145. doi: 10.1155/2023/3869145. eCollection 2023.
NADC34-like porcine reproductive and respiratory virus (PRRSV) has had a significant impact on the pig industry, particularly in China. However, the evolutionary characteristics and pathogenicity of NADC34-like PRRSV strains within intensive farming systems are not well understood, particularly regarding the biological characteristic variation of successive outbreaks on a farm. In this study, we conducted continuous surveillance in an intensive farm that experienced a PRRSV outbreak. Two PRRSV strains, GDHZ109/2020 and GDYS162/2022, were isolated and fully sequenced from the same swine farm in Guangdong Province in 2020 and 2022, respectively. Evolutionary analysis based on the ORF5 gene revealed that both strains clustered with NADC34-like strains and shared 96.5% homology. Analysis of the full-length genome and NSP2 gene classified the strains into lineage 1.8, represented by the NADC30 strain. Recombination analysis suggested complex recombination patterns for both strains, involving NADC30-like, NADC34-like, and JXA1-like strains. Although many recombinant regions were nearly identical, there were differences observed in the NSP5-NSP7 region. Pathogenicity experiments conducted on piglets demonstrated that GDHZ109/2020 exhibited higher pathogenicity compared to GDYS162/2022. Piglets in the GDHZ109/2020 infected group had more severe clinical signs and higher mortality. Moreover, analysis of respiratory microbial diversity indicated a significant increase in the abundance of potentially pathogenic microbiota, such as and contributing to the respiratory tract of PRRSV-infected piglets, suggesting secondary infections due to differences in immune defense. These findings highlight the importance of NADC34-like recombinant strains' evolution during the farm's epidemic period, which may have contributed to changes in pathogenicity. This study improves our understanding of the current prevalence of PRRSV and provides novel insights into the prevention and control of PRRSV.
类NADC34猪繁殖与呼吸综合征病毒（PRRSV）对养猪业产生了重大影响，尤其是在中国。然而，集约化养殖系统中类NADC34 PRRSV毒株的进化特征和致病性尚未得到充分了解，特别是关于农场连续疫情的生物学特性变化。在本研究中，我们对一个发生PRRSV疫情的集约化农场进行了持续监测。分别于2020年和2022年从广东省的同一个猪场分离出两株PRRSV毒株GDHZ109/2020和GDYS162/2022，并进行了全基因组测序。基于开放阅读框5（ORF5）基因的进化分析表明，这两株毒株均与类NADC34毒株聚类，同源性为96.5%。对全长基因组和非结构蛋白2（NSP2）基因的分析将这些毒株归类为以NADC30毒株为代表的1.8谱系。重组分析表明，这两株毒株均具有复杂的重组模式，涉及类NADC30、类NADC34和类JXA1毒株。尽管许多重组区域几乎相同，但在NSP5 - NSP7区域观察到了差异。对仔猪进行的致病性实验表明，与GDYS162/2022相比，GDHZ109/2020表现出更高的致病性。GDHZ109/2020感染组的仔猪临床症状更严重，死亡率更高。此外，对呼吸道微生物多样性的分析表明，潜在致病微生物群的丰度显著增加，如 和 ，这些微生物群存在于PRRSV感染仔猪的呼吸道中，提示免疫防御差异导致继发感染。这些发现突出了类NADC34重组毒株在猪场疫情期间进化的重要性，这可能导致了致病性的变化。本研究提高了我们对当前PRRSV流行情况的认识，并为PRRSV的预防和控制提供了新的见解。
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