title: Expression of HPV-11 L1 protein in transgenic Arabidopsis thaliana and Nicotiana tabacum.
abstract: BACKGROUND
  We have investigated the possibility and feasibility of producing the HPV-11 L1 major capsid protein in transgenic Arabidopsis thaliana ecotype Columbia and Nicotiana tabacum cv. Xanthi as potential sources for an inexpensive subunit vaccine.
  
  
  RESULTS
  Transformation of plants was only achieved with the HPV-11 L1 gene with the C-terminal nuclear localization signal (NLS-) encoding region removed, and not with the full-length gene. The HPV-11 L1 NLS- gene was stably integrated and inherited through several generations of transgenic plants. Plant-derived HPV-11 L1 protein was capable of assembling into virus-like particles (VLPs), although resulting particles displayed a pleomorphic phenotype. Neutralising monoclonal antibodies binding both surface-linear and conformation-specific epitopes bound the A. thaliana-derived particles and - to a lesser degree - the N. tabacum-derived particles, suggesting that plant-derived and insect cell-derived VLPs displayed similar antigenic properties. Yields of up to 12 microg/g of HPV-11 L1 NLS- protein were harvested from transgenic A. thaliana plants, and 2 microg/g from N. tabacum plants - a significant increase over previous efforts. Immunization of New Zealand white rabbits with approximately 50 microg of plant-derived HPV-11 L1 NLS- protein induced an antibody response that predominantly recognized insect cell-produced HPV-11 L1 NLS- and not NLS+ VLPs. Evaluation of the same sera concluded that none of them were able to neutralise pseudovirion in vitro.
  
  
  CONCLUSIONS
  We expressed the wild-type HPV-11 L1 NLS- gene in two different plant species and increased yields of HPV-11 L1 protein by between 500 and 1000-fold compared to previous reports. Inoculation of rabbits with extracts from both plant types resulted in a weak immune response, and antisera neither reacted with native HPV-11 L1 VLPs, nor did they neutralise HPV-11 pseudovirion infectivity. This has important and potentially negative implications for the production of HPV-11 vaccines in plants.
authors.affiliation: Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, PO Observatory 7925, Cape Town, South Africa. thomas.kohl@jefferson.edu
authors.forename: Thomas O
authors.initials: TO
authors.lastname: Kohl
authors.forename: Inga I
authors.initials: II
authors.lastname: Hitzeroth
authors.forename: Neil D
authors.initials: ND
authors.lastname: Christensen
authors.forename: Edward P
authors.initials: EP
authors.lastname: Rybicki
mesh_terms: D000818:Animals; D000914:Antibodies, Viral; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D036022:Capsid Proteins / Q000096:biosynthesis* / Q000276:immunology / Q000302:isolation & purification; D015870:Gene Expression; D052140:Human papillomavirus 11 / Q000235:genetics; D006801:Humans; D009500:Neutralization Tests; D009856:Oncogene Proteins, Viral / Q000096:biosynthesis* / Q000276:immunology / Q000302:isolation & purification; D030361:Papillomavirus Infections / Q000276:immunology / Q000517:prevention & control; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism*; D015202:Protein Engineering / Q000379:methods; D011817:Rabbits; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000276:immunology / Q000302:isolation & purification; D014026:Nicotiana / Q000235:genetics / Q000378:metabolism*; D014614:Vaccines, Synthetic / Q000235:genetics / Q000276:immunology; D014765:Viral Vaccines / Q000138:chemical synthesis / Q000235:genetics; D019065:Virus Assembly
chemical_list: D000914:Antibodies, Viral; D036022:Capsid Proteins; C094776:L1 protein, Human papillomavirus type 11; D009856:Oncogene Proteins, Viral; D011994:Recombinant Proteins; D014614:Vaccines, Synthetic; D014765:Viral Vaccines