Chimaeric plant virus stimulates influenza virus-specific CD8+ T-cell responses

Plant-produced potato virus X chimeric particles displaying an influenza virus-derived peptide activate specific CD8+ T cells in mice

 Chiara Lico, Camillo Mancini, Paola Italiani, Camilla Betti, Diana Boraschi, Eugenio Benvenuto, Selene Baschieri

 Vaccine (2009) 27: 5069 – 5076

 The authors used plant Potexvirus Potato virus X (PVX) to display the Db-restricted nonapeptide ASNENMETM of the nucleoprotein (NP) from influenza A virus (strain A/PR/8/34) to activate specific CD8+ T cells in mice. They paid great attention to the design of the NP-peptide to ensure optimum plant virus stability and antigen processing. The modified NP-peptide was fused to the N-terminal of the coat protein (CP) from PVX creating the pVXSma-NP construct that was subsequently inoculated into tobacco leaves. The resulting chimeric virus particles (NP-CVP) were stable and pure with a yield of approximately 1.1 mg NP-CVP / g fresh leaf tissue. Endotoxin tests were also performed to exclude their contribution to the immunoregulatory effects of the CVPs. Mice were inoculated with two different doses of NP-CVP (50 µg or 167 µg) with or without incomplete Freund’s adjuvant (IFA). The IFN-γ ELISPOT assays indicated that NP-CVPs activated the ASNENMETM-specific CD8+ response, especially the highest concentration of the NP-CVP without the adjuvant. Results also indicated that the CP of PVX contained T helper epitopes that contributed to the CD8+ T cell response. Thus, PVX is not only an epitope carrier but an adjuvant as well. This study illustrates the potential of implementing plant viruses displaying foreign epitopes to elicit T cell responses in vaccine development.

Contributed by Dr Elizabeth (Liezl) Mortimer

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2 Responses to “Chimaeric plant virus stimulates influenza virus-specific CD8+ T-cell responses”

  1. Dorian McILROY Says:

    Anybody tried pseudotyping an enveloped plant virus with HA and NA to get neutralizing antibodies? TSWV comes to mind, since the envelope glycoproteins aren’t needed for systemic plant infection.

    DMc

  2. Ed Rybicki Says:

    Dorian: I agree, this would be a seriously cool idea…BUT there is no real need; it is quite possible that plant-expressed HA proteins (or other envelope glycoproteins, for that matter) are expressed at higher level in even transgenic plants than plant virus envelope glycoproteins may be – and in the case of influenza HA proteins at any rate, not only associate as trimers, but in fact bud out of the cell membrane as small virus-like vesicles, which are more immunogenic than free protein AND protective in animal models. See M. A. D’Aoust, P. O. Lavoie, M. M. Couture, S. Trepanier, J. M. Guay, M. Dargis, S. Mongrand, N. Landry, B. J. Ward, and L. P. Vezina. Influenza virus-like particles produced by transient expression in Nicotiana benthamiana induce a protective immune response against a lethal viral challenge in mice. Plant Biotechnol.J. 6 (9):930-940, 2008.

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