Submitted to: International Congress of Virology
Publication Type: Abstract Only
Publication Acceptance Date: 5/23/2005
Publication Date: 7/1/2005
Citation: Natilla, A., Hammond, R., Zhao, Y., Nemchinov, L.G. 2005. Display of vaccine candidate antigens on the surface of cucumber mosaic virus coat protein, expressed through a potato virus x vector. International Congress of Virology. p.163.
Technical Abstract: Background. Plant viruses do not replicate in animals, providing significant safety advantages over the use of animal virus-based vectors for vaccine delivery. Many plant viral coat proteins have the ability to assemble into virus-like particles (VLPs) which can be used as a scaffold to display heterologous peptides, most notably of which are vaccine antigens. Cucumber mosaic virus (CMV) is an icosohedral plant virus whose capsid is composed of 180 copies of the 24 kDa coat protein. We have previously made peptide fusions to the capsid protein (CP) of CMV to express either a 17 amino acid (aa) neutralizing epitope of the Newcastle Disease Virus (NDV) fusion (F) protein or an 8 aa neutralizing epitope of the NDV hemagglutinin-neuraminidase (HN) protein (Zhao and Hammond, 2005). Fusions were made in the internal ßH-ßI loop (motif 5) within the CMV CP. In this study, we have introduced recombinant CMV CP coding sequences into the efficient Potato virus X (PVX)-based vector to achieve a high-level production of these potential anti-NDV vaccine candidates in plants. Methods. Recombinant sequences obtained by PCR, were introduced into PVX vector for transient expression in host plant Nicotiana benthamiana. Plants were inoculated with in vitro synthesized T7 RNA transcripts and tested for protein expression. Results. Plants infected with recombinant PVX produced substantial amounts of CMV CP and developed characteristic PVX symptoms. Chimeric CMV CP reacted with CMV-specific polyclonal antibodies as well as with epitope-specific monoclonal antibodies to NDV. Alternatively, PVX-expressed wild type CMV CP carrying no NDV epitopes reacted only with CMV antibodies. Recombinant CMV VLPs were purified from PVX-infected leaves using a standard purification method developed for wild-type CMV virions (Lot et al., 1972). Preliminary data indicated that CMV CP expressed from PVX is capable of assembling stable virus-like particles (VLP) presenting immunoreactive NDV epitopes and contain CP RNA. Conclusions. Transient high-level production of CMV cVLPs and immunoreactivity of NDV epitopes displayed on its surface demonstrate that CMV CP can be successfully expressed through heterologous plant virus vector, retain its capacity to assemble into VLPs, and act as a carrier molecule for the presentation of foreign epitopes.