Degree Type

Dissertation

Date of Award

2017

Degree Name

Doctor of Philosophy

Department

Veterinary Microbiology and Preventive Medicine

Major

Veterinary Microbiology

First Advisor

Jeffrey J. Zimmerman

Abstract

The objectives of this research were to determine the effects of maternally-derived antibodies in protecting piglets against porcine epidemic diarrhea virus (PEDV). In Chapter 3, a passive antibody transfer model was used to evaluate the impact of circulating antibody on the protection of naïve piglets against PEDV. Piglets derived from 6 sows were randomly assigned to receive one of 6 different levels of concentrated serum antibody. In Chapter 4, PEDV-immune and PEDV-negative sows were used to evaluate the impact of lactogenic antibody on the protection of piglets against PEDV. In both studies, piglets were inoculated with PEDV and monitored for 14 days, during which time they remained with their dam. Sow milk, piglet fecal samples, and data on piglet clinical signs, body weight, and body temperature were collected daily. Serum, colostrum, and milk were tested for PEDV antibody by PEDV IgG and IgA ELISAs and by fluorescent focus neutralization (FFN) assay. The analysis showed that both passive antibody and lactogenic antibody contributed to the protection of the neonatal piglets against PEDV infections. Therefore, the optimal protection to piglets will be provided by dams able to deliver sufficient lactogenic immunity, both humoral and cellular, to their offspring.

The feasibility of improving oral fluid IgG and/or IgA antibody testing by clarifying samples using chemical treatment was evaluated in Chapter 5. Three chemical formulations based on chitosan and/or Tween-20® were used to treat aliquots of known status oral fluid samples from PEDV-inoculated pigs. All aliquots were tested by PEDV IgG and IgA ELISAs on day post-treatment (DPT) 0, then kept at 4°C and re-tested on DPT 2, 4, and 6. All formulations went into solution quickly and easily upon addition of oral fluid and the addition of chitosan was shown to effectively clarify oral fluids. Statistical analysis found that neither chitosan nor Tween-20® adversely affected the ELISA results and the treated oral fluid samples were stable over time. Thus, this study found that chitosan could be used to efficiently clarify oral fluid specimens without affecting the results of antibody ELISAs.

DOI

https://doi.org/10.31274/etd-180810-5733

Copyright Owner

Korakrit Poonsuk

Language

en

File Format

application/pdf

File Size

146 pages

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