Isolation and Nsp2 gene sequence analysis of the PRRSV TM isolate

The TM isolate of porcine reproductive and respiratory syndrome virus(PRRSV) was isolated from a affected pig in Guangdong province.RT-PCR and sequence analysis showed that the virus belonged to the North American strain.However,the Nsp2 protein of the virus had a total of 30 amino acids deletion in aa481 and aa532 to aa560,compared with the North American standard strain VR-2332.In addition,the TM isolate had another unique 21 amino acids deletion at aa22 to aa42 within its Nsp2-coding region comparing with other PRRSV variant isolated in China recent years.Animal regression experiment showed that the virus could cause significantly clinical symptoms and viremia in piglets.Thus,the TM isolate represents a newly emerged PRRSV variant.