Generation of a cold-adapted PRRSV with a nucleotide substitution in the ORF5 and numerous mutations in the hypervariable region of NSP2

A cold-adapted porcine reproductive and respiratory syndrome virus (CA-VR2332) was generated from the modified live virus strain VR2332. CA-VR2332 showed impaired growth when cultured at 37°C with numerous mutations (^S731^F, ^E819^D, ^G975^E, and ^D1014^N) in the hypervariable region of the NSP2, in which the mutation ^S731^F might play a vital role in viral replication at 30°C. Conserved amino acid sequences of the GP5 protein suggests that CA-VR2332 is a promising candidate for producing an effective vaccine against PRRSV infection. Further studies on replication and immunogenicity in vivo are required to evaluate the properties of CA-VR2332.