Immunogenicity of a recombinant parapoxvirus expressing the spike protein of Porcine epidemic diarrhea virus

Abstract

The parapoxvirus Orf virus (ORFV), has long been recognized for its immunomodulatory properties in permissive and non-permissive animal species. Here, a new recombinant ORFV expressing the full-length spike (S) protein of Porcine epidemic diarrhea virus (PEDV) was generated and its immunogenicity and protective efficacy were evaluated in pigs. The PEDV S was inserted into the ORFV121 gene locus, an immunomodulatory gene that inhibits activation of the NF-κB signalling pathway and contributes to ORFV virulence in the natural host. The recombinant ORFV-PEDV-S virus efficiently and stably expressed the PEDV S protein in cell culture in vitro. Three intramuscular (IM) immunizations with the recombinant ORFV-PEDV-S in 3-week-old pigs elicited robust serum IgG, IgA and neutralizing antibody responses against PEDV. Additionally, IM immunization with the recombinant ORFV-PEDV-S virus protected pigs from clinical signs of porcine epidemic diarrhoea (PED) and reduced virus shedding in faeces upon challenge infection. These results demonstrate the suitability of ORFV121 gene locus as an insertion site for heterologous gene expression and delivery by ORFV-based viral vectors. Additionally, the results provide evidence of the potential of ORFV as a vaccine delivery vector for enteric viral diseases of swine. This study may have important implications for future development of ORFV-vectored vaccines for swine.

Identification and characterization of linear B cell epitopes on the nucleocapsid protein of porcine epidemic diarrhea virus using monoclonal antibodies

“…An S-protein based ELISA was established and proved better than an N-protein based ELISA (Knuchel et al, 1992). However, the S-protein has great variability (Sun et al, 2008;Hain et al, 2016;Oh et al, 2014). Further, the neutralizing McAb of the protein could not inactivate PEDV strain with other genotype .…”

The S2 glycoprotein subunit of porcine epidemic diarrhea virus contains immunodominant neutralizing epitopes

“…PEDV S-specific mAbs were generated and selected based on the reactivity of the mAbs with full length PEDV S expressed by a recombinant viral vector (ORFV-PEDV-S) (Hain et al, 2016) (Fig. 1).…”

“…Given its critical functions during cell entry, the PEDV S protein is the main target of host neutralizing antibodies against the virus . Indeed, several studies have recently shown that immunization of pigs with full-length or truncated versions of the S protein elicits antibody responses and protection against PEDV (Hain et al, 2016;Makadiya et al, 2016;Oh et al, 2014). Most importantly, at least four neutralizing domains have been identified in the S protein, including: 1) a domain recently mapped to the NTD/S0 region (Li et al, 2017), 2) a domain that is homologous to the collagenase resistant fragment (CO-26K) of TGEV S (Godet et al, 1994), thus being named "collagenase equivalent" (COE) in PEDV (residues 499-638) (Chang et al, 2002), 3) an epitope that has been mapped to the S1D region (residues 636-789) and spans the S1-S2 junction region (Sun et al, 2008), and 4) an epitope mapped to C-terminus of the S protein (residues 1371-1377) (Cruz et al, 2008).…”

Identification of the immunodominant neutralizing regions in the spike glycoprotein of porcine deltacoronavirus

“…In addition, the S protein is postulated to harbor epitopes that induce neutralizing antibodies Zumla et al, 2016). Hain et al (Hain et al, 2016) generated a recombinant Orf virus (ORFV) that expresses the fulllength PEDV S protein. An immunization challenge study in pigs showed that intramuscular inoculation with ORFV-PEDV-S elicited Sspecific IgG, IgA, and a neutralizing antibody response.…”