Faten A. Okda

Document Type

Dissertation - Open Access

Award Date

2017

Degree Name

Doctor of Philosophy (PhD)

Department / School

Veterinary and Biomedical Sciences

First Advisor

Eric A. Nelson

Keywords

coronavirus, diagnostic, emerging viruses, influenza d, livestock, surveillances

Abstract

Accurate and rapid diagnostic tests are essential for the management and control of emerging infectious diseases. Therefore, the overall goals of studies presented in this dissertation were to provide improved diagnostic and surveillance capabilities for several emerging viral diseases impacting the livestock industry and to provide insight into appropriate control strategies. Recent, severe outbreaks of porcine epidemic diarrhea virus (PEDV) in Asia and North America highlighted the need for well-validated diagnostic tests for identification of PEDV infected animals and evaluation of their immune status. PEDV was first detected in the U.S. in May 2013 and another swine coronavirus, porcine deltacoronavirus (PDCoV) was identified in the U.S. in February 2014. Both pathogens spread rapidly across the U.S., severely impacting the swine industry. As part of this project, well-validated serological assays for the detection of antibodies against PEDV and PDCoV were developed. Monoclonal antibodies (mAbs) against selected PEDV and PDCoV structural proteins were also developed and applied to serological and antigen detection assays. Newly developed fluorescence-based virus neutralization assays also provide valuable tools for assessment of vaccine candidates or protective immunity. The PEDV spike (S) glycoprotein plays a key role in virus entry into target cells and mediates the functions of receptor binding and fusion during entry. Therefore, immunodominant neutralizing epitopes of PEDV were identified using a panel of S-specific mAbs. Epitope mapping by peptide ELISA revealed that seven mAbs recognized linear neutralizing epitopes located in the N-terminus of the S2 glycoprotein subunit. Two mAbs recognized a neutralizing epitope located in the C-terminus of S2, while only one neutralizing mAb reacted against a region of the S1 glycoprotein subunit. These results indicate that the S2 glycoprotein subunit contains major antigenic determinants and, perhaps, the immunodominant neutralizing epitopes of PEDV. Influenza D virus is a recently described virus that affects cattle and limited serological testing capability is currently available. Therefore, new ELISA-based serological assays based on expressed protein antigens representing conserved regions of the nucleoprotein and hemagglutinin-esterase proteins were developed. Results of these assays correlate well with hemagglutination inhibition (HI) and virus neutralization assays, providing new tools for ongoing sero-surveillance and control efforts.

Library of Congress Subject Headings

Veterinary virology.
Coronaviruses.
Sendai virus.

Description

Includes bibliographical references

Format

application/pdf

Number of Pages

225

Publisher

South Dakota State University

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Rights Statement

In Copyright