Isolation and bioinformatics analysis of the NADC30_Like CJS01 strain of the porcine reproductive and respiratory syndrome virus.

In this study, lung tissue was collected from nursery piglets suspected of being infected with porcine reproductive and respiratory syndrome virus (PRRSV) in a large­scale pig farm in Sichuan, China. Polymerase chain reaction (PCR) and reverse transcription quantitative­polymerase chain reaction (RT­qPCR) methods were used to ensure that no other pathogens were present. Virus isolation was also carried out where the presence of PRRSV was determined by indirect immunoinfluscent assay (IFA). Compared with the common PRRSV strain, the isolate did not produce evident Cytopathic effect (CPE) in the early stage of isolation. CPE was found in the late stage, and the titer was 104.17 TCID50/0.1 mL. The strain was named CJS01. Bioinformatics analysis showed that it was a NADC30­Like strain. The virus load was determined by measuring the nucleic acid load during the proliferation of the strain on Marc­145 cells. The strain showed good adaptability on cells, and the virus proliferated on cells for 84 hr when the highest nucleic acid load was achieved. By recombinant analysis of ORF3~7 genes and prediction of its epitope, it was found that CJS01 strain might interfere with the immunesystem of the infected animals.