Fig. 1From: A persistent epidemic of porcine epidemic diarrhoea virus infection by serological survey of commercial pig farms in northern VietnamReactivity of pig sera from three provinces to PED whole viral antigen in indirect ELISA.The asterisk indicates the significant difference based on one-way ANOVA test. (*, Pā<ā0.001; NS, not significant). The dotted line indicates the cut-off value (0.320) of the ELISABack to article page