title: Increased yield of heterologous viral glycoprotein in the seeds of homozygous transgenic tobacco plants cultivated underground.
abstract: The use of transgenic plants in the production of recombinant proteins for human therapy, including subunit vaccines, is being investigated to evaluate the efficacy and safety of these emerging biopharmaceutical products. We have previously shown that synthesis of recombinant glycoprotein B (gB) of human cytomegalovirus can be targeted to seeds of transgenic tobacco when directed by the rice glutelin 3 promoter, with gB retaining critical features of immunological reactivity (E.S. Tackaberry et al. 1999. Vaccine, 17: 3020-3029). Here, we report development of second generation transgenic plant lines (T1) homozygous for the transgene. Twenty progeny plants from two lines (A23T(1)-2 and A24T(1)-3) were grown underground in an environmentally contained mine shaft. Based on yields of gB in their seeds, the A23T(1)-2 line was then selected for scale-up in the same facility. Analyses of mature seeds by ELISA showedthat gB specific activity in A23T(1)-2 seeds was over 30-fold greater than the best T0 plants from the same transformation series, representing 1.07% total seed protein. These data demonstrate stable inheritance, an absence of transgene inactivation, and enhanced levels of gB expression in a homozygous second generation plant line. They also provide evidence for the suitability of using this environmentally secure facility to grow transgenic plants producing therapeutic biopharmaceuticals.
authors.affiliation: Centre for Biologics Research, Biologics and Genetic Therapies Directorate, Health Canada, Ottawa, ON K1A 0L2, Canada. eilleen_tackaberry@hc.sc.gc.ca
authors.forename: Eilleen S
authors.initials: ES
authors.lastname: Tackaberry
authors.forename: Fiona
authors.initials: F
authors.lastname: Prior
authors.forename: Margaret
authors.initials: M
authors.lastname: Bell
authors.forename: Monika
authors.initials: M
authors.lastname: Tocchi
authors.forename: Suzanne
authors.initials: S
authors.lastname: Porter
authors.forename: Jelica
authors.initials: J
authors.lastname: Mehic
authors.forename: Peter R
authors.initials: PR
authors.lastname: Ganz
authors.forename: Ravinder
authors.initials: R
authors.lastname: Sardana
authors.forename: Illimar
authors.initials: I
authors.lastname: Altosaar
authors.forename: Anil
authors.initials: A
authors.lastname: Dudani
mesh_terms: D003433:Crosses, Genetic; D004797:Enzyme-Linked Immunosorbent Assay; D005983:Glutens / Q000235:genetics; D030821:Plants, Genetically Modified / Q000502:physiology*; D012639:Seeds / Q000737:chemistry*; D014026:Nicotiana / Q000235:genetics* / Q000502:physiology*; D014759:Viral Envelope Proteins / Q000096:biosynthesis*
chemical_list: D014759:Viral Envelope Proteins; C040495:glycoprotein B, Simplexvirus; D005983:Glutens