Serum and mammary secretion antibody responses in porcine epidemic diarrhea-immune gilts following porcine epidemic diarrhea vaccination

Abstract

Objective: In the sow herd, maintaining levels of immunity sufficient to protect neonatal pigs is an important aspect in porcine epidemic diarrhea virus (PEDV) control. This study compared anamnestic responses to two commercially available PEDV vaccines. Materials and methods: PEDV antibody-positive gilts (n = 36) in a commercial production system were each randomly (www.random.org) assigned to one of five vaccination protocols: no vaccine (controls); PEDV vaccine A (2 weeks pre-farrow); PEDV vaccine A (5 and 2 weeks pre-farrow); PEDV vaccine B (2 weeks pre-farrow); and PEDV vaccine B (5 and 2 weeks pre-farrow). Serum, colostrum, and milk samples collected over the course of the study were tested for PEDV IgG, IgA, and neutralizing antibody (NAb). Results: Analysis of the data from 32 animals completing the study found that vaccine induced a clear anamnestic response, ie, vaccinates had higher antibody concentrations than controls for most tests and specimens, but no difference was detected between one versus two doses of vaccine, and few differences in response were detected for vaccine A versus B. A positive but weak correlation was detected between IgG in serum and IgA in colostrum (P = .012; r = .44). Implications: Under the conditions of this study, PEDV-vaccinated gilts have higher IgG, IgA, and NAb responses than nonvaccinated controls in all diagnostic specimens tested. In breeding herds, direct measurement of PEDV IgA or NAb in colostrum and milk will provide a more accurate measurement of lactogenic immunity than serological testing.