Analysis of Genetic Variation of Two NADC30-like Strains of Porcine Reproductive and Respiratory Syndrome Virus in China

BACKGROUND: NADC30-like strains of porcine reproductive and respiratory syndrome virus first appeared in Chinese swine herds in 2012. OBJECTIVE AND METHOD: To explore the possible genetic diversity of these strains, we sequenced and analyzed the complete genomes of two NADC30-like strains. These isolates shared 95.4% homology with NADC30. RESULT: The two strains displayed a discontinuous deletion of 131 amino acids in NSP2, mutations of amino acids in GP3 and GP5, and a 3-nucleotide deletion in the 3′ untranslated region. Phylogenetic analysis showed that the two isolates formed a new branch and clustered in a subgroup with NADC30 isolates from North America. CONCLUSION: We conclude that the above two NADC30-like strains may have been introduced from North America to China, where they acquired new genetic diversity.