Porcine circovirus type 2 protective epitope densely carried by chimeric papaya ringspot virus–like particles expressed in Escherichia coli as a cost‐effective vaccine manufacture alternative

Abstract

Porcine circovirus type 2 (PCV2) still represents a major problem to the swine industry worldwide, causing high mortality rates in infected animals. Virus-like particles (VLPs) have gained attention for vaccine development, serving both as scaffolds for epitope expression and immune response enhancers. The commercial subunit vaccines against PCV2 consist of VLPs formed by the self-assembly of PCV2 capsid protein (CP) expressed in the baculovirus vector system. In this work, a PCV2 protective epitope was inserted into three different regions of papaya ringspot virus (PRSV) CP, namely, the N- and C-termini and a predicted antigenic region located near the N-terminus. Wild-type and chimeric CPs were modeled in silico, expressed in Escherichia coli, purified, and visualized by transmission electron microscopy. This is the first report that shows the formation of chimeric VLPs using PRSV as epitope-presentation scaffold. Moreover, it was found that PCV2 epitope localization strongly influences VLP length. Also, the estimated yields of the chimeric VLPs at a small-scale level ranged between 65 and 80 mg/L of culture medium. Finally, the three chimeric VLPs induced high levels of immunoglobulin G against the PCV2 epitope in immunized BALB/c mice, suggesting that these chimeric VLPs can be used for swine immunoprophylaxis against PCV2.

Expression of PCV2d Capsid Protein in Escherichia coli and its Evaluation for Serodiagnosis of Porcine Circovirus Infection

“…Many positive charge arginine-rich N terminus sequences impede efficient expression and optimization of the E. coli expression system's sequence [13]. The full-length sequence 1-234 expresses the pcv2d capsid protein.…”

Development of a Platform for Noncovalent Coupling of Full Antigens to Tobacco Etch Virus-Like Particles by Means of Coiled-Coil Oligomerization Motifs

“…The observation of particles of up to 1 um demonstrated the utility of the method to obtain VLPs. Previous reports demonstrated that the addition of foreign sequences in the amino terminus of potyviral CPs did not hamper VLP formation [ 30 , 31 , 32 ]. It was confirmed that the TEVK protein retains its ability to self-assemble into VLPs in the presence of GFPE-N or GFPE-C. Characteristically, TEVK VLPs showed less surface uniformity, suggesting protuberances due to the possible interaction between CP monomers and the K-coil motifs or, when it corresponds, the heterogeneous binding of GFPE in the surface of VLP ( Figure 6 ).…”

The truncated form of flagellin (tFlic) provides the 2dCap subunit vaccine with better immunogenicity and protective effects in mice

“…Cap can self-assemble to form virus-like particles (VLPs) of 60 subunits (Khayat et al, 2011 ). These VLPs have a structure similarity to that of virions that elicits strong B cell-mediated responses and cytotoxic T lymphocyte-mediated responses, but they lack nucleic acids, which reduce the risk of viral spread; thus, VLPs are a hot topic in vaccine development research (Aguilera et al, 2017 ; Chae, 2016 ; Fachinger et al, 2008 ; Rosano and Ceccarelli, 2014 ; Yin et al, 2010 ). Epidemiological findings from an increasing number of studies revealed that PCV2d (a PCV2b mutant with reportedly higher virulence) has emerged and spread rapidly in Chinese swine herds (Xiao et al, 2015 ).…”