Evaluation and Comparison of the Pathogenicity and Host Immune Responses Induced by a G2b Taiwan Porcine Epidemic Diarrhea Virus (Strain Pintung 52) and Its Highly Cell-Culture Passaged Strain in Conventional 5-Week-Old Pigs.

Yen-Chen Chang,Chi-Fei Kao,Ivan-Chen Cheng,Victor Pang,Chia-Yu Chang,Hui-Wen Chang,Ju-Yi Peng,Pei-Shiue Tsai,Chian-Ren Jeng,Hue-Ying Chiou

doi:10.3390/v9050121

Yen-Chen Chang, Chi-Fei Kao + Show 8 more

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https://doi.org/10.3390/v9050121

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Abstract

A genogroup 2b (G2b) porcine epidemic diarrhea virus (PEDV) Taiwan Pintung 52 (PEDVPT) strain was isolated in 2014. The pathogenicity and host antibody responses elicited by low-passage (passage 5; PEDVPT-P5) and high-passage (passage 96; PEDVPT-P96) PEDVPT strains were compared in post-weaning PEDV-seronegative pigs by oral inoculation. PEDVPT-P5-inoculation induced typical diarrhea during 1–9 days post inoculation with fecal viral shedding persisting for 26 days. Compared to PEDVPT-P5, PEDVPT-P96 inoculation induced none-to-mild diarrhea and lower, delayed fecal viral shedding. Although PEDVPT-P96 elicited slightly lower neutralizing antibodies and PEDV-specific immunoglobulin G (IgG) and immunoglobulin A (IgA) titers, a reduction in pathogenicity and viral shedding of the subsequent challenge with PEDVPT-P5 were noted in both PEDVPT-P5- and PEDVPT-P96-inoculated pigs. Alignment and comparison of full-length sequences of PEDVPT-P5 and PEDVPT-P96 revealed 23 nucleotide changes and resultant 19 amino acid substitutions in non-structure proteins 2, 3, 4, 9, 14, 15, spike, open reading frame 3 (ORF3), and membrane proteins with no detectable deletion or insertion. The present study confirmed the pathogenicity of the PEDVPT isolate in conventional post-weaning pigs. Moreover, data regarding viral attenuation and potency of induced antibodies against PEDVPT-P5 identified PEDVPT-P96 as a potential live-attenuated vaccine candidate.

Highlights

Porcine epidemic diarrhea (PED) is caused by the PED virus (PEDV), which belongs to the Alphacoronavirus genus of the family Coronaviridae
No CPE and positive porcine epidemic diarrhea virus (PEDV) antigen signals were detected in Vero cells not inoculated with media containing PEDV Pingtung 52 (PEDVPT) (Figure 1D)
We have demonstrated that this genogroup 2b (G2b) PEDVPT-P5 strain can induce typical watery diarrhea in 5-week-old pigs but milder symptoms and a shorter viral shedding period in 9-week-old pigs

Summary

Introduction

Porcine epidemic diarrhea (PED) is caused by the PED virus (PEDV), which belongs to the Alphacoronavirus genus of the family Coronaviridae. RNA genome of approximately 28 kb in size, which encodes four structural proteins, namely, spike (S), Viruses 2017, 9, 121; doi:10.3390/v9050121 www.mdpi.com/journal/viruses. Viruses 2017, 9, 121 envelope (E), membrane (M), and nucleocapsid (N) proteins as well as three non-structural proteins (NSP), namely, replicases 1a and 1b and open reading frame 3 (ORF3). During the 1980s and 1990s, PED caused severe economic losses in the swine industry in Europe and Asia, but it later turned into a sporadic disease [1]. The disease has rapidly spread to Asia and, subsequently, to North America, and has resulted in the death of millions of pigs, and has severely affected the swine industry [3,4]

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