Basing on the scientific reports, PCV2 is the necessary cause agents of the porcine respiratory disease complex (PRDC) and the post-weaning multisystemic wasting syndrome (PMWS). Unfortunately, PCV2 infection dispersed all around the Taiwan island. Therefore, it is difficult to obtain the pigs without anti-PCV2 antibody in Taiwan. We will establish the pigs free from PCV2 antibody in this project at first. The selected pathogens, PCV2, PRRSV and Teschovirus, which were isolated from pig herd are inoculated orally to the pigs without anti-PCV2 antibody. It is to know the correlation between the pathogens and pathogenesis in pig farm, and to figure out the control measures of emerging disease in pig farm.