ANALYSIS - Emerging strains of Porcine Reproductive and Respiratory Syndrome (PRRS) can develop on a regularly basis and every few years a particularly virulent strain will arise and cause waves of disease, reports Sarah Mikesell from the North American PRRS Symposium."We do not know exactly how these happen, but the genetic changes have to involve mutation and recombination, and the consequences are bad," said Michael Murtaugh, professor and scientist at the University of Minnesota.

　　北美猪繁殖与呼吸综合征((PRRS))研讨会莎拉克赛尔(Sarah Mikesell)报告，新兴的猪繁殖与呼吸综合征菌株按照基础的定期规律发展，每几年会浮现一个尤其的病毒菌株，并引起一波波的疾病。明尼苏达大学科学家迈克尔莫塔夫(Michael Murtaugh)教授说“我们不能尽全知道这是如何发生的，但是基因改变包括突变和重组，这样产生的结果是不利的”。