Isolation of porcine reproductive and respiratory syndrome (PRRS) virus from Heko-Heko disease of pigs.

Porcine reproductive and respiratory syndrome (PRRS) virus was isolated at high frequency from the sera and lungs of pigs affected with Heko-Heko disease. In addition, a considerable amount of Mycoplasma hyorhinis (Mhr) was also isolated from the lungs. Inoculation of gnotobiote pigs with the first isolate of PRRS virus resulted in the reproduction of proliferative and interstitial pneumonia. The virus was recovered from the inoculated pigs for long periods. Superinfection with PRRS virus and Mhr appeared to produce more serious pneumonia than inoculation with PRRS virus alone. In this study, the presence of PRRS virus was confirmed in Japan, and the PRRS virus was considered as being the most important pathogen for Heko-Heko disease.