title: Boosted expression of the SARS-CoV nucleocapsid protein in tobacco and its immunogenicity in mice.
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.
authors.affiliation: State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Datun Road, Beijing 100101, China.
authors.forename: Nuoyan
authors.initials: N
authors.lastname: Zheng
authors.forename: Ran
authors.initials: R
authors.lastname: Xia
authors.forename: Cuiping
authors.initials: C
authors.lastname: Yang
authors.forename: Bojiao
authors.initials: B
authors.lastname: Yin
authors.forename: Yin
authors.initials: Y
authors.lastname: Li
authors.forename: Chengguo
authors.initials: C
authors.lastname: Duan
authors.forename: Liming
authors.initials: L
authors.lastname: Liang
authors.forename: Huishan
authors.initials: H
authors.lastname: Guo
authors.forename: Qi
authors.initials: Q
authors.lastname: Xie
mesh_terms: D000276:Adjuvants, Immunologic / Q000008:administration & dosage / Q000494:pharmacology; D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D000086462:Coronavirus Nucleocapsid Proteins; D005260:Female; D005620:Freund's Adjuvant / Q000008:administration & dosage / Q000494:pharmacology; D020868:Gene Silencing; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D007274:Injections, Intraperitoneal; D007371:Interferon-gamma / Q000378:metabolism; D016753:Interleukin-10 / Q000378:metabolism; D007963:Leukocytes, Mononuclear / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D019590:Nucleocapsid Proteins / Q000235:genetics / Q000276:immunology* / Q000302:isolation & purification; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification; D045473:Severe acute respiratory syndrome-related coronavirus / Q000235:genetics / Q000276:immunology*; D013154:Spleen / Q000276:immunology; D014026:Nicotiana / Q000235:genetics / Q000378:metabolism*; D017864:Tombusvirus / Q000235:genetics; D022223:Vaccines, Subunit / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification
chemical_list: D000276:Adjuvants, Immunologic; D000914:Antibodies, Viral; D000086462:Coronavirus Nucleocapsid Proteins; D007074:Immunoglobulin G; D019590:Nucleocapsid Proteins; D011994:Recombinant Proteins; D022223:Vaccines, Subunit; D016753:Interleukin-10; D007371:Interferon-gamma; D005620:Freund's Adjuvant