... pigs of the coinfected group had symptoms typical of PHFS, such as high fever, anorexia, and red coloration of the ears and the body. The isolation rates of HP-PRRSV and SS7 were higher and the ... effects on the immune system, and allow sec-ondary infection by SS7, thereby further exacerbating the damage to the immune system. In addition, neurotoxicityis an important feature of PRRSV infection ... infection. Further characterizati on of PHFS of pigs under laboratory and natural conditionswill be necessary to understand the mechanisms under-lying the enhanced susceptibility of HP-PRRSV-infectedpigs...