一株NSP2蛋白连续缺失48个氨基酸的高致病性猪繁殖与呼吸综合征病毒株的分离及其主要生物学特征的研究

Isolation and identification of a variant HP-PRRSV with deletion 48 amino acid in NSP2

为研究猪繁殖与呼吸综合征病毒(PRRSV)遗传变异特点,本研究在PRRSV流行病学调查中分离到一株PRRSV,该分离株在高致病性PRRSV(HP-PRRSV)NSP2区1 aa+29 aa缺失的基础上,突变为49 aa+29 aa的缺失株,将其命名为Henan-A14(NCBI序列号:KJ819936)。此外,该分离株在MARC-145细胞中的复制能力减弱,即其细胞嗜性有所改变。血清中和试验结果显示5份HP-PRRSV疫苗抗血清均不能中和该分离株,推测其抗原发生了较大变异。为鉴定该缺失是否影响病毒的复制,本研究以HP-PRRSV p Hu N4-F112株的感染性克隆为骨架,拯救出一株在NSP2区相应位置连续缺失48 aa的重组病毒,而该重组病毒在MARC-145细胞中的复制及血清中和试验结果表明,NSP2基因区48 aa缺失既不影响PRRSV的复制效率,也不影响病毒对HP-PRRSV制备的阳性血清中和效率。本研究的结果证明Henan-A14分离株在MARC-145细胞中复制能力的降低,以及病毒抗原中和表位与NSP2中相关的氨基酸缺失无直接关系。该分离株的鉴定为进一步研究HP-PRRSV的变异具有重要的参考价值。

To investigate the genetic diversity of porcine reproductive and respiratory syndrome virus （PRRSV）, a PRRSV （designated Henan-A14） was isolated and sequencing analyzed, which had a additional 48 amino acid （aa） deletion adding to 49 aa ＋29 aa mutations in NSP2 based on the 1 aa＋29 aa deletion for characterization of the highly pathogenic PRRSV （HP-PRRSV）. In addition, the isolate was poorly replicated in MARC-145 cells, exhibiting a different cell tropism. Furthermore, the virus isolate was unable to be neutralized with the antiserum derived from pigs immunized with HP-PRRSV vaccine （HuN4-F112 strain）, indicating that the crucial antigens for inducing neutralization antibody had mutated in the isolate. However, the replication of the chimeric virus, derived from HP-PRRSV vaccine strain of HuN4-F112 strain with the 48 aa deletion, had no significant different in MARC-145 cells comparing with its parental virus. The identification of the new mutation virus provided a reference for further study on the mutations of NSP2 and PRRSV.