Evaluation of responses to both oral and parenteral immunization modalities for porcine epidemic diarrhea virus in production units

The immune responses (serum anti-porcine epidemic diarrhea virus [PEDV] immunoglobulin G [IgG] and milk antiviral neutralizing antibodies) induced by various combinations of two PEDV immunization modalities (vaccine and oral immunization) were examined in unrelated swine production units in different locations. Anti-PEDV antibodies were undetectable in serum and milk of the control group (non-vaccinated and non-infected). Sows in the unit that received only the PED vaccine (iPED+; Harrisvaccines, Inc, Ames, Iowa) (two doses) remained naive for the wild-type virus and did not develop milk anti-PEDV neutralizing immunoglobulin titers as high as those in the other three production units; which had received oral immunization. Milk anti-PEDV antibody titers in the orally immunized sows appeared to be of longer duration than serum antiviral IgG concentrations. This indicates that oral immunization may be the more efficacious PEDV immunization modality, especially with regard to the production of milk antiviral antibody levels.