1株类NADC30猪繁殖与呼吸综合征病毒重组毒株的分离鉴定及致病性分析OA

[Objective]This study aimed to isolate and identify Porcine reproductive and respiratory syndrome virus(PRRSV)from clinically typical cases,analyze the genetic evolution and pathogenicity of epidemic viruses,and provide a reference for PRRSV prevention and control in Shandong region.[Method]The supernatant from homogenized PRRSV-positive lung tissue was inoculated into African green monkey kidney cells(Marc-145)for virus isolation.The isolated strain was identified by indirect immunofluorescence assay(IFA)and transmission electron microscopy(TEM).The whole-genome sequencing and genetic evolution analysis of the isolated strain were conducted.The pathogenicity of the isolated strain was evaluated in 30-day-old piglets.[Result]Following three blind passages,the supernatant from PRRSV-positive lung tissue was used to inoculate Marc-145 cells.After 48 h of infection,Marc-145 cells exhibited obvious cytopathic effects,including shrinkage,rounding,and aggregation.IFA results revealed distinct clustered fluorescence in cells at 24 h post-infection.Transmission electron microscopy observed viral particles 50-60 nm in diameter within cytoplasmic vesicles,consistent with the structural size of PRRSV.These results confirmed the successful isolation of a PRRSV strain,with a viral titer of 105.65 TCID50/mL,which was designated as CH-SDTA-2501.Whole-genome sequencing revealed the full genome of the virus was 15 001 bp in length.Phylogenetic and recombination analysis revealed that CH-SDTA-2501 strain belonged to the NADC30 branch,and it was a recombinant strain derived from NADC30 and JXA1.Piglets was challenged with CH-SDTA-2501(1×105.0 TCID50)via intranasal and intramuscular infection,respectively.After 3 days post-infection,piglets developed respiratory symptoms including coughing and dyspnea.And the virus was detected in serum.Moreover,gross lesions at 14 days post-inoculation showed pulmonary consolidation and interstitial thickening.Histopathological examination further revealed thickened alveolar septa and epithelial cell hyperplasia.[Conclusion]This study successfully isolated a NADC30-like PRRSV strain,which could induce significant respiratory symptoms in piglets.The findings provided novel insights for PRRSV prevention and control.