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Severe acute respiratory syndrome (SARS) S protein production in plants: development of recombinant vaccine

Pogrebnyak, N., Golovkin, M., Andrianov, V., Spitsin, S., Smirnov, Y., Egolf, R., Koprowski, H.
Proceedings of the National Academy of Sciences of the United States of America 2005 v.102 no.25 pp. 9062-9067
Nicotiana tabacum, tobacco, Solanum lycopersicum var. lycopersicum, tomatoes, transgenic plants, gene expression, transgenes, recombinant antigens, viral antigens, Coronavirus, viral diseases of animals and humans, recombinant vaccines, immune response, oral administration, antibody formation, immunoglobulin A, immunoglobulin G, mice
In view of a recent spread of severe acute respiratory syndrome (SARS), there is a high demand for production of a vaccine to prevent this disease. Recent studies indicate that SARS-coronavirus (CoV) spike protein (S protein) and its truncated fragments are considered the best candidates for generation of the recombinant vaccine. Toward the development of a safe, effective, and inexpensive vaccine candidate, we have expressed the N-terminal fragment of SARS-CoV S protein (S1) in tomato and low-nicotine tobacco plants. Incorporation of the S1 fragment into plant genomes as well as its transcription was confirmed by PCR and RT-PCR analyses. High levels of expression of recombinant S1 protein were observed in several transgenic lines by Western blot analysis using specific antibodies. Plant-derived antigen was evaluated to induce the systemic and mucosal immune responses in mice. Mice showed significantly increased levels of SARS-CoV-specific IgA after oral ingestion of tomato fruits expressing S1 protein. Sera of mice parenterally primed with tobacco-derived S1 protein revealed the presence of SARS-CoV-specific IgG as detected by Western blot and ELISA analysis.