In the study , respiratory problems and blue ear were not observed on all the pigs after challenged with prrsv strain ch - 1a . but the rectal temperatures of the pigs in the negative control groups ( plers1neo - immunized group and mock group ) were higher than the pigs immunized with the dna vaccines Prrsv的感染一般为亚临床表现，在本试验中，攻毒后所有的小猪都没有出现呼吸困难、耳朵发兰等症状，但空白对照猪和空质粒接种猪的体温要高于基因疫苗免疫猪和灭活苗免疫猪，最高可达40石c 。
