title: Transplastomic expression of a modified human papillomavirus L1 protein leading to the assembly of capsomeres in tobacco: a step towards cost-effective second-generation vaccines.
abstract: Certain types of human papillomaviruses (HPV) are causatively associated with cervical carcinoma, the second most common cancer in women worldwide. Due to limitations in the availability of currently used virus-like particle (VLP)-based vaccines against HPV to women of developing countries, where most cases of cervical cancer occur, the development of a cost-effective second-generation vaccine is a necessity. Capsomeres have recently been demonstrated to be highly immunogenic and to have a number of advantages as a potential cost-effective alternative to VLP-based HPV vaccines. We have expressed a mutated HPV-16 L1 (L1_2xCysM) gene that retained the ability to assemble L1 protein to capsomeres in tobacco chloroplasts. The recombinant protein yielded up to 1.5% of total soluble protein. The assembly of capsomeres was examined and verified by cesium chloride density gradient centrifugation and sucrose sedimentation analysis. An antigen capture enzyme-linked immunosorbent assay confirmed the formation of capsomeres by using a conformation-specific monoclonal antibody which recognized the conformational epitopes. Transplastomic tobacco plants exhibited normal growth and morphology, but all such lines showed male sterility in the T₀, T₁ and T₂ generations. Taken together, these results indicate the possibility of producing a low-cost capsomere-based vaccine by plastids.
authors.affiliation: Department of Applied Plant Sciences and Plant Biotechnology (DAPP), University of Natural Resources and Applied Life Sciences (BOKU), Gregor-Mendel-Strasse 33, 1180, Vienna, Austria.
authors.forename: M Tahir
authors.initials: MT
authors.lastname: Waheed
authors.forename: Nadja
authors.initials: N
authors.lastname: Thönes
authors.forename: Martin
authors.initials: M
authors.lastname: Müller
authors.forename: S Waqas
authors.initials: SW
authors.lastname: Hassan
authors.forename: N Mona
authors.initials: NM
authors.lastname: Razavi
authors.forename: Elke
authors.initials: E
authors.lastname: Lössl
authors.forename: Hans-Peter
authors.initials: HP
authors.lastname: Kaul
authors.forename: Andreas G
authors.initials: AG
authors.lastname: Lössl
mesh_terms: D002213:Capsid / Q000276:immunology / Q000378:metabolism*; D036022:Capsid Proteins / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D002736:Chloroplasts / Q000378:metabolism* / Q000821:virology; D005260:Female; D052162:Human papillomavirus 16 / Q000235:genetics / Q000378:metabolism; D006801:Humans; D009154:Mutation; D009856:Oncogene Proteins, Viral / Q000235:genetics / Q000378:metabolism; D030361:Papillomavirus Infections / Q000517:prevention & control; D053918:Papillomavirus Vaccines / Q000191:economics* / Q000235:genetics / Q000276:immunology; D030821:Plants, Genetically Modified / Q000235:genetics* / Q000276:immunology; D014026:Nicotiana / Q000235:genetics / Q000378:metabolism* / Q000821:virology; D019076:Transgenes; D058425:Vaccines, Virus-Like Particle / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D014771:Virion / Q000378:metabolism; D019065:Virus Assembly
chemical_list: D036022:Capsid Proteins; D009856:Oncogene Proteins, Viral; D053918:Papillomavirus Vaccines; D058425:Vaccines, Virus-Like Particle; C063317:L1 protein, Human papillomavirus type 16