Plant-Produced Antigen Displaying Virus-Like Particles Evokes Potent Antibody Responses against West Nile Virus in Mice

Abstract

In this study, we developed a hepatitis B core antigen (HBcAg)-based virus-like particle (VLP) that displays the West Nile virus (WNV) Envelope protein domain III (wDIII) as a vaccine candidate for WNV. The HBcAg-wDIII fusion protein was quickly produced in Nicotiana benthamiana plants and reached a high expression level of approximately 1.2 mg of fusion protein per gram of leaf fresh weight within six days post gene infiltration. Electron microscopy and gradient centrifugation analysis indicated that the introduction of wDIII did not interfere with VLP formation and HBcAg-wDIII successfully assembled into VLPs. HBcAg-wDIII VLPs can be easily purified in large quantities from Nicotiana benthamiana leaves to >95% homogeneity. Further analysis revealed that the wDIII was displayed properly and demonstrated specific binding to an anti-wDIII monoclonal antibody that recognizes a conformational epitope of wDIII. Notably, HBcAg-wDIII VLPs were shown to be highly immunogenic and elicited potent humoral responses in mice with antigen-specific IgG titers equivalent to that of protective wDIII antigens in previous studies. Thus, our wDIII-based VLP vaccine offers an attractive option for developing effective, safe, and low-cost vaccines against WNV.

A Plant-Produced Virus-Like Particle Displaying Envelope Protein Domain III Elicits an Immune Response Against West Nile Virus in Mice

“…These findings illustrate that a significantly lower dose of immunogen is required to elicit a potent immune response when the antigen is displayed on the surface of a particle, compared with the dose when it is used as an immunogen on its own. Interestingly, similar antibody titres to the soluble WNV-EDIII were observed in studies reported from a different laboratory where mice were immunised with 25 µg of either plant-produced soluble WNV-EDIII (He et al, 2014;Lai et al, 2018), or WNV-EDIII displayed on the surface of HBcAg (He et al, 2021). Their immunisation dose was five times more than what was used in our study, however, we observed similar or superior antibody binding titres with our lower dose of soluble WNV-EDIII and AP205:EDIII VLPs, respectively.…”

“…In a recent study by He et al HBcAg-WNV-EDIII VLPs were produced in N. benthamiana at a yield of 1.2 g/kg FLW (He et al, 2021 ). In this study, we report a yield of ~10 mg/kg FLW and from previous experiments, we have obtained a yield of purified AP205:EDIII VLPs of ~36 mg/kg FLW.…”

Plant-Derived Recombinant Vaccines against Zoonotic Viruses

“…Only the results of sucrose gradient centrifugation suggested the assembly of prM-E VLPs [51]. They also fused wEDIII to HBcAg, and produced chimeric VLPs, which elicited strong B and T-cell responses against WNV in mice [204].…”

Producing Vaccines against Enveloped Viruses in Plants: Making the Impossible, Difficult

“…This review describes work involving production in plants of domain III of the E protein of WNV (wEDIII), which was shown to be immunogenic [ 121 ] and probably even protective in mice [ 122 ], and hints at the production of the entire E protein as well as WNV VLPs produced in plants from expression of a prM-E construct, though this does not appear to have been published. There are, however, examples of wEDIII fused to HBcAg, which yields immunogenic core-like particles that stimulate an immune response against WNV in mice [ 123 ]. Using a similar strategy, domain III of the E protein of Zika virus (ZIKV, zEDIII) was displayed on the surface of HBcAg particles, and these were found to be highly immunogenic in mice [ 124 ].…”