title: Transgenic plant production of Cyanovirin-N, an HIV microbicide.
abstract: Cyanovirin-N (CV-N) is a microbicide candidate that inactivates a wide range of HIV strains by binding to gp120. Production of CV-N, or any protein microbicide, needs to be at extremely high levels and low cost to have an impact on global health. Thus, it is unlikely that fermentor-based systems will be suitable, including recombinant E. coli, where CV-N aggregates and dimers have consistently been found. Transgenic plants may provide a suitable expression system for protein microbicides, as production can be easily and economically scaled up. Here, Nicotiana tabacum was transformed with a gene encoding CV-N to explore proof of concept for the production of CV-N in transgenic plants. Plant-derived rCV-N was recoverable at levels of 130 ng/mg of fresh leaf tissue, or at least 0.85% of total soluble plant protein. Western blot analysis demonstrated that virtually all of the rCV-N was expressed in the desired monomeric form. Functionality was demonstrated by specific binding to gp120 and protection of T-cells from in vitro HIV infection. Hydroponic culturing of transgenic plants demonstrated CV-N rhizosecretion at levels of 0.64 mug/ml hydroponic media after 24 days. Therefore, we suggest that transgenic plants have the potential to provide strategies for large-scale protein microbicide production.
authors.affiliation: Centre for Infection, Department of Cellular and Molecular Medicine, St. George's University of London, London, UK. a.sexton@sgul.ac.uk
authors.forename: Amy
authors.initials: A
authors.lastname: Sexton
authors.forename: Pascal M
authors.initials: PM
authors.lastname: Drake
authors.forename: Naheed
authors.initials: N
authors.lastname: Mahmood
authors.forename: Sarah J
authors.initials: SJ
authors.lastname: Harman
authors.forename: Robin J
authors.initials: RJ
authors.lastname: Shattock
authors.forename: Julian K-C
authors.initials: JK
authors.lastname: Ma
mesh_terms: D019380:Anti-HIV Agents / Q000378:metabolism*; D001426:Bacterial Proteins / Q000096:biosynthesis* / Q000737:chemistry / Q000235:genetics; D002352:Carrier Proteins / Q000096:biosynthesis* / Q000737:chemistry / Q000235:genetics; D015870:Gene Expression; D015699:HIV Envelope Protein gp120 / Q000378:metabolism; D018515:Plant Leaves / Q000378:metabolism; D030821:Plants, Genetically Modified; D011485:Protein Binding; D014026:Nicotiana / Q000235:genetics* / Q000378:metabolism*
chemical_list: D019380:Anti-HIV Agents; D001426:Bacterial Proteins; D002352:Carrier Proteins; D015699:HIV Envelope Protein gp120; C107733:cyanovirin N