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Abstract：
China has the largest pig herd in the world which accounts for more than 50% of the global pig population. Over the past three decades, the porcine reproductive and respiratory syndrome virus (PRRSV) has caused significant economic loss to the Chinese swine industry. Currently, the prevalent PRRSV strains in the field are extremely complicated, and the NADC30-like strains, NADC34-like strains, and novel recombinant viruses have become a great concern to PRRS control in China. In this study, a novel NADC30-like PRRSV, named GS2022, was isolated from the lung of a dead pig collected from a farm that experienced a PRRS outbreak. The complete genome of GS2022 shares the highest identity with the NADC30 strain and contains a discontinuous deletion of 131 aa in nsp2. Novel deletion and insertion have been identified in ORF7 and 3\'UTR. Recombination analysis revealed that the GS2022 is a potential recombinant of NADC30-like and JXA1-like strains. Both inter-lineage and intra-lineage recombination events were predicted to be involved in the generation of the GS2022. An infectious cDNA clone of GS2022 was assembled to generate the isogenic GS2022 (rGS2022). The growth kinetics of rGS2022 were almost identical to those of GS2022. The pathogenicity of the GS2022 and rGS2022 was evaluated using a nursery piglet model. In the infection groups, the piglets exhibited mild clinical symptoms, including short periods of fever and respiratory diseases. Both gross lesions and histopathological lesions were observed in the lungs and lymph nodes of the infected piglets. Therefore, we reported a novel recombinant NADC30-like PRRSV strain with moderate pathogenicity in piglets. These results provide new information on the genomic characteristics and pathogenicity of the NADC30-like PRRSV in China.
摘要：
中国拥有世界上最大的猪群，占全球生猪种群的50％以上。在过去的三十年里，猪繁殖与呼吸综合征病毒（PRRSV）给中国养猪业造成了巨大的经济损失。目前,该领域流行的PRRSV毒株非常复杂，和类似NADC30的菌株，NADC34样菌株，和新型重组病毒已成为中国PRRS控制的重要问题。在这项研究中,一种新颖的类似NADC30的PRRSV，名为GS2022，是从从经历PRRS爆发的农场收集的死猪的肺中分离出来的。GS2022的完整基因组与NADC30菌株具有最高的同一性，并且在nsp2中包含131个aa的不连续缺失。已在ORF7和3'UTR中鉴定了新的缺失和插入。重组分析表明，GS2022是NADC30样和JXA1样菌株的潜在重组体。预测谱系间和谱系内重组事件都参与GS2022的生成。组装GS2022的感染性cDNA克隆以产生等基因GS2022(rGS2022)。rGS2022的生长动力学与GS2022几乎相同。使用保育仔猪模型评估GS2022和rGS2022的致病性。在感染组中，仔猪表现出轻微的临床症状，包括短时间的发烧和呼吸道疾病。在感染仔猪的肺和淋巴结中均观察到了大体病变和组织病理学病变。因此,我们报道了一种在仔猪中具有中等致病性的新型重组NADC30样PRRSV株。这些结果为NADC30样PRRSV在中国的基因组特征和致病性提供了新的信息。
