Abstract
Porcine epidemic diarrhea (PED) is a diarrheal disease of swine caused by porcine epidemic diarrhea virus (PEDV). It is characterized by acute watery diarrhea, dehydration and vomiting in swine of all ages and is especially fatal for neonatal and postweaning piglets. The spike protein of PEDV plays an important role in mediating virus attachment and fusion to target cells, and recent studies also reported that the neutralizing epitopes of the spike protein were mainly located in the S1 subunit, which makes it a candidate for vaccine development and clinical diagnosis. In this study, we successfully constructed an immune phage display single-domain antibody library with a library size of 3.4 × 106. A single-domain antibody, named S7, specific for the spike protein of PEDV was identified from the phage display single-domain antibody library. S7 could be expressed in a soluble form in E. coli, bound to the spike protein of PEDV in ELISA and stained the PEDV virus in Vero cells, but it showed no neutralization activity on PEDV. These results indicated the potent application of the S7 antibody as an imaging probe or as a candidate for the development of a diagnostic assay.
Highlights
Porcine epidemic diarrhea (PED) is a diarrheal disease of swine caused by the porcine epidemic diarrhea virus (PEDV)
Expression and purification of PEDV spike protein The truncated spike gene of PEDV was PCR amplified with a pair of specific primers
A single specific gene fragment with a molecular weight of approximately 1000 bp was obtained from the amplification as shown in Fig. 1a, and the sequencing result showed that the gene fragment corresponded to the 1330–2310 bp of the PEDV spike protein gene (444–770 amino acids, data not shown)
Summary
Porcine epidemic diarrhea (PED) is a diarrheal disease of swine caused by the porcine epidemic diarrhea virus (PEDV). It is characterized by acute watery diarrhea, dehydration and vomiting in swine of all ages and is especially fatal for neonatal and postweaning piglets. Several outbreaks have been reported in Asian countries, such as South Korea, China and Japan, and they have been characterized by relatively high mortality rates ranging from 50 to 95%, causing severe damage to the swine industry (Lee 2015; Song et al 2015b). In the late autumn of 2010, a large-scale outbreak of diarrhea characterized by severe watery diarrhea, dehydration with high morbidity and mortality emerged in a swine farm in southern China, and it has affected an estimated millions of piglets and greatly threatened the global swine industry. The accumulated evidence suggests that the causative agent of the disease was PEDV with a possible variation (Li et al 2012; Song et al 2015a; Tian et al 2013)
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