The introduction of oral fluid-based sampling is a relatively new concept in diagnostic medicine which has been rapidly adopted by the swine industry. While the detection of porcine reproductive and respiratory syndrome virus (PRRSV) and influenza A (IAV) in oral fluids has been well documented, research on the detection of most other pathogens requires additional research.
Therefore, the objective of the study described in Chapter 3 was to describe PEDV detection patterns in growing pigs as shown by PEDV rRT-PCR testing of pen oral fluids. While feces have traditionally been the dominant sample for PEDV detection, the research in Chapter 3 describes oral fluids as a practical sample type for PEDV detection in growing pigs. Specifically, PEDV was detected in oral fluids until 69 days post exposure (DPE) which was longer than pen feces (55 DPE) and individual fecal swabs (41 DPE). PEDV Cq values in oral fluids were comparable to PEDV Cq values in pen feces; however, PEDV Cq values in oral fluids and pen feces were significantly higher than individual fecal swabs.
Chapter 3 described PEDV antibody kinetics, as shown by ELISA detection of IgA and IgG in individual pig serum and pen oral fluid samples and provided estimates of the cutoffs and performance of the PEDV whole virus IgA and IgG ELISAs. PEDV antibody responses (IgG and IgA) were detected in both serum and oral fluid by 10 - 14 days post exposure. The oral fluid PEDV IgA responses were particularly noteworthy with the maximum oral fluid IgA response reported at 96 DPE.
The investigators evaluated anamnestic antibody responses of gilts previously exposed to PEDV through vaccination using serum, colostrum, and milk samples in Chapter 4. Using 5 different vaccination protocols (unvaccinated controls and one and/or 2 doses of either Vaccine A or Vaccine B), the investigators found that two doses of vaccine did not booster immune responses any more than one dose of vaccine did. This was not unexpected since these gilts had been exposed to PEDV 8 months early. Nevertheless, the results in Chapter 4 demonstrate that vaccination can booster immune responses in previously exposed gilts
