Abstract
Vaccines produced in plant systems are safe and economical; however, the extensive application of plant-based vaccines is mainly hindered by low expression levels of heterologous proteins in plant systems. Here, we demonstrated that the post-transcriptional gene silencing suppressor p19 protein from tomato bushy stunt virus substantially enhanced the transient expression of recombinant SARS-CoV nucleocapsid (rN) protein in Nicotiana benthamiana. The rN protein in the agrobacteria-infiltrated plant leaf accumulated up to a concentration of 79 microg per g fresh leaf weight at 3 days post infiltration. BALB/c mice were intraperitoneally vaccinated with pre-treated plant extract emulsified in Freund's adjuvant. The rN protein-specific IgG in the mouse sera attained a titer about 1:1,800 following three doses of immunization, which suggested effective B-cell maturation and differentiation in mice. Antibodies of the subclasses IgG1 and IgG2a were abundantly present in the mouse sera. During vaccination of rN protein, the expression of IFN-gamma and IL-10 was evidently up-regulated in splenocytes at different time points, while the expression of IL-2 and IL-4 was not. Up to now, this is the first study that plant-expressed recombinant SARS-CoV N protein can induce strong humoral and cellular responses in mice.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Adjuvants, Immunologic / administration & dosage
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Adjuvants, Immunologic / pharmacology
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Animals
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Antibodies, Viral / blood
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Coronavirus Nucleocapsid Proteins
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Female
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Freund's Adjuvant / administration & dosage
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Freund's Adjuvant / pharmacology
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Gene Silencing
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Humans
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Immunoglobulin G / blood
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Injections, Intraperitoneal
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Interferon-gamma / metabolism
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Interleukin-10 / metabolism
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Leukocytes, Mononuclear / immunology
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Mice
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Mice, Inbred BALB C
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Nicotiana / genetics
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Nicotiana / metabolism*
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Nucleocapsid Proteins / genetics
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Nucleocapsid Proteins / immunology*
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Nucleocapsid Proteins / isolation & purification
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Plants, Genetically Modified / genetics
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Plants, Genetically Modified / metabolism*
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Recombinant Proteins / genetics
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Recombinant Proteins / immunology
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Recombinant Proteins / isolation & purification
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Severe acute respiratory syndrome-related coronavirus / genetics
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Severe acute respiratory syndrome-related coronavirus / immunology*
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Spleen / immunology
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Tombusvirus / genetics
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Vaccines, Subunit / genetics
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Vaccines, Subunit / immunology
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Vaccines, Subunit / isolation & purification
Substances
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Adjuvants, Immunologic
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Antibodies, Viral
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Coronavirus Nucleocapsid Proteins
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Immunoglobulin G
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Nucleocapsid Proteins
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Recombinant Proteins
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Vaccines, Subunit
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Interleukin-10
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Interferon-gamma
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Freund's Adjuvant