Porcine Reproductive and Respiratory Syndrome Virus Engineered by Serine Substitution on the 44th Amino Acid of GP5 Resulted in a Potential Vaccine Candidate with the Ability to Produce High Levels of Neutralizing Antibody

Abstract

N-linked glycans covering GP5 neutralizing epitopes of porcine reproductive and respiratory syndrome virus (PRRSV) have been proposed to act as a sheath blocking the production of neutralizing antibodies. Herein, we genetically engineered PRRSV with serine (S) substitution on the 44th asparagine (N) on the GP5 ectodomain of PRRSV-2 lineage-1. To evaluate the recombinant PRRSV, in vivo experiments were performed in piglets. The recombinant virus group showed no viremia until 42 days post-inoculation (dpi), and the rectal temperature and average daily weight gain were in the normal range at the same time point as the negative control group. On the 42 dpi, both groups were challenged with the wild-type virus. The recombinant PRRSV group showed lower rectal temperature, viremia, and the lung lesions than that of the negative control group for 19 days post-challenge (dpc). Additionally, the recombinant virus induced 4.50 ± 3.00 (log2) and 8.25 ± 0.96 (log2) of neutralizing antibody before and after challenge, respectively. Taken together, this study confirmed that N44S substitution can create an infectious PRRSV that strongly induces neutralizing antibodies. In addition, the vCSL1-GP5-N44S mutant that we produced was confirmed to have potential as a vaccine candidate, showing good safety and protective effects in pigs.

Mass Spectrometry-Based Proteomic Analysis of Potential Host Proteins Interacting with GP5 in PRRSV-Infected PAMs

“…Of these, structural protein GP5 serves as a major virulence determinant. It is the preferred protein for developing new vaccines due to its important immune domains such as neutralizing epitope, antigenic determinants, and glycosylation sites [ 15 , 16 , 17 , 18 , 19 , 20 ]. Moreover, GP5 plays a vital role not only in PRRSV infection, cell binding, and immune evasion, but also in cell apoptosis [ 21 , 22 , 23 , 24 , 25 ].…”

Development of a Ferritin Protein Nanoparticle Vaccine with PRRSV GP5 Protein

“…Numerous studies have demonstrated that the neutralizing antibodies induced by these two epitopes can effectively reduce the lethality of PRRSV infection in pigs and are, therefore, important targets for the development of subunit vaccines [17][18][19]. Although GP5 is considered to be an ideal target for the design of novel vaccines, some experimental vaccines based on the expression of the native GP5 protein, such as subunit vaccines, viral vector vaccines, DNA vaccines, and so on, often fail to induce higher neutralizing antibodies [18,[20][21][22][23][24][25]. Additionally, there is also a nonneutralizing decoy epitope (aa 27-31) located upstream of the neutralizing epitope GP5B (aa [37][38][39][40][41][42][43][44][45], which may hinder the recognition of the GP5B epitope and the subsequent development of neutralizing antibodies [15].…”

One-Step Assembly of a PRRSV Infectious cDNA Clone and a Convenient CRISPR/Cas9-Based Gene-Editing Technology for Manipulation of PRRSV Genome

“…Presently, many live-attenuated vaccine candidates are generated by altering the virulence genes in the PRRSV genome through the reverse genetics systems [ 19 ]. Additionally, an immunogenically enhancing vaccine candidate that possesses a stronger ability to induce neutralizing antibody has been developed by mutating the glycosylation sites in GP5 [ 20 , 21 , 22 ]. Moreover, four regions in the PRRSV genome, including the interval between ORF1b and ORF2, the spacer between ORF4 and ORF5a, the position post-ORF7, and the highly variable region within nsp2, have been applied for carrying exogenous genes using a reverse genetics system, which provides the potential for the development of polyvalent vaccines based on PRRSV [ 23 , 24 , 25 , 26 ].…”