Molecular Epidemiology and Characterization of Porcine Epidemic Diarrhea Virus in Korea

다국어 초록 (Multilingual Abstract)

Porcine Epidemic Diarrhea Virus (PEDV) is an economically important pathogen of swine. Its global impact on the swine industry has caused financial losses amounting to millions of dollars in revenue. Because of this, production of several strains of PEDV as live attenuated vaccine candidates has been a major goal of several pharmaceutical and research institutes. While an attenuated vaccine provides an effective means to induce humoral, as well as cell-mediated immune responses against PEDV, several factors have to be considered in selecting the most appropriate vaccine candidate for mass production. One of the most critical factors to consider when selecting attenuated strains as vaccine candidate is its close genetic similarity with the circulating strains. In Korea, the predominant strains that circulated between 2004 and 2006 showed close similarity with the Korean strain (Spk1) based on the N-terminal sequence of the spike protein. In contrast, most of the present vaccine candidates are derived from the European isolates CV777 and Br1/87 strains. The local strains of PEDV diverge dramatically from these strains. Because the spike protein is an important structural component in PEDV infection, the significant difference in the morphological and antigenic properties between the current vaccine strains used and the circulating strains may compromise the efficacy of the vaccine. Thus, a thorough investigation on the prevalent strain of PEDV is required prior to implementing the distribution of live vaccine to swine. Furthermore, identifying the prevalent strain is essential for selecting the appropriate live vaccine candidate for distribution.
While PEDV has been rampant in Europe and Asia, only a small number of studies have been done to characterize the virus, particularly the S protein. This is an important factor since many of the recombinant and sub-unit vaccine candidates depend on the efficacy of vaccines to induce antibody production in that has neutralizing activity against PEDV, particularly the S protein. A thorough investigation of this important surface glycoprotein is essential in understanding the mechanism of viral infection and eventually, formulating strategies in preventing them.

목차 (Table of Contents)

• Chapter I. General Introduction 1
• I. Porcine Epidemic Diarrhea Virus 2
• A. Emergence of Porcine Epidemic Diarrhea 2
• B. Clinical and Pathological Symptoms of PED 3
• C. Geographical Distribution of PEDV 6
• D. Taxonomic Classification and Genomic Organization of PEDV 8
• E. PEDV Replication Cycle 10
• F. Current Vaccines being developed against PEDV 14
• II. References15
• Chapter II. Molecular Surveillance of PEDV in Korea from
• 2004 to 2005 21
• I. Introduction 22
• II. Materials and Methods 27
• III. Results 35
• IV. Discussion 42
• V. References 45
• Chapter III. Detection of a novel antigenic determinant of PEDV using a phage-peptide library system 49
• I. Introduction 50
• II. Materials and Methods 51
• III. Results 56
• IV. Discussion 65
• V. References 69
• Chapter IV. Development of a Focus Formation Assay
• Method for Detection and Titration of PEDV 75
• I. Introduction 76
• II. Materials and Methods 78
• III. Results 86
• IV. Discussion 92
• V. References 95
• Chapter V. Molecular Characterization of the PEDV Spike Protein 101
• I. Introduction 102
• II. Materials and Methods 104
• III. Results 107
• IV. Discussion 114
• V. References 118