Resistance of field-isolated porcine epidemic diarrhea virus to interferon and neutralizing antibody

Abstract

Abstract Porcine epidemic diarrhea virus (PEDV) infects pigs and causes enteric disease characterized by watery diarrhea and dehydration. Despite the extensive vaccination, PEDV strains with variations in the spike gene have been reported in several countries, including Korea, China, and the United States. Variant PEDV belonging to genogroup G2 has higher pathogenicity and morbidity than conventional PEDV belonging to genogroup G1. To understand the pathogenesis of the variant PEDV, we examined the susceptibility of the variant PEDV to interferon and PEDV specific neutralizing antibodies, which are known to important for the control of PEDV infection. We found that variant PEDV (WG strain) showed higher resistance to interferon than conventional PEDV (KPEDV-9 strain). Similarly, KPEDV-9 strain grew well in interferon-deficient Vero cells but did not grow in interferon-releasing porcine alveolar macrophages, whereas WG strain showed similar infectivity in both cells. We also found that WG strain is not blocked by the neutralizing antibodies against KPEDV-9, suggesting the differences in the antigenicity of two strains. To elucidate the possible mechanism of resistance to interferon and neutralizing antibody in variant PEDV, sequencing analysis was performed. We found huge variations in spike and ORF3 proteins. Our results indicate that the recently introduced variant PEDV exhibits higher resistance to the interferon than the existing PEDV and avoids the neutralizing antibody against the existing PEDV. These results also provide understanding of the occurrence of variant PEDV and its pathogenesis.