Measurement of neutralizing antibodies against porcine epidemic diarrhea virus in sow serum, colostrum, and milk samples and piglet serum samples after feedback

Abstract

The introduction of porcine epidemic diarrhea virus (PEDV) into the naive US swine population in April 2013 resulted in significant mortality. The high mortality rates observed indicated the need to boost herd immunity to PEDV. To optimize feedback protocols or other future control measures used to increase immunity, a fluorescent focus neutralization (FFN) assay was developed and used to determine the titers of neutralizing antibodies in sow serum, milk, and colostrum samples and in piglet serum samples. Sow serum samples from two farm sites within different production systems (A, B) were tested. At least 24 sows per site were screened for neutralizing antibodies at 0, 3, 6, 7, and 24 weeks post feedback (PF). These functional antibodies were detected in sow serum samples at both sites 3, 6, 7, and 24 weeks PF and in milk and colostrum samples by 7 weeks PF. At 6 weeks PF, neutralizing antibodies were detected in 27 of 30 Site A piglets (90%), compared to 15 of 29 Site B piglets (52%). Piglets at both sites had detectable neutralizing antibodies, and sentinel pigs were successfully introduced into both systems without re-infection with PEDV by 24 weeks PF.