Emergence and Reemergence of Porcine Reproductive and Respiratory Syndrome Virus (PRRSV).

PRRSV has obsessed world pig industry for decades though the commercial vaccines and stamping-out policy have been widely used in many countries. So far, PRRSV is still prevalent in North America and most Asian countries and leads to huge economic losses. PRRSV is notorious for its quick rate of mutation and recombination that may lead to the change of virulence. A good example is the emergence of highly pathogenic PRRSV (HP-PRRSV) in 2006 that led to huge amount of economic losses in Chinese pig industry.