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

Transgenic Res. 2011 Apr;20(2):271-82. doi: 10.1007/s11248-010-9415-4. Epub 2010 Jun 19.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Capsid / immunology
  • Capsid / metabolism*
  • Capsid Proteins* / biosynthesis
  • Capsid Proteins* / genetics
  • Capsid Proteins* / immunology
  • Capsid Proteins* / metabolism
  • Chloroplasts / metabolism*
  • Chloroplasts / virology
  • Female
  • Human papillomavirus 16 / genetics
  • Human papillomavirus 16 / metabolism
  • Humans
  • Mutation
  • Oncogene Proteins, Viral* / genetics
  • Oncogene Proteins, Viral* / metabolism
  • Papillomavirus Infections / prevention & control
  • Papillomavirus Vaccines / economics*
  • Papillomavirus Vaccines / genetics
  • Papillomavirus Vaccines / immunology
  • Plants, Genetically Modified / genetics*
  • Plants, Genetically Modified / immunology
  • Tobacco / genetics
  • Tobacco / metabolism*
  • Tobacco / virology
  • Transgenes
  • Vaccines, Virus-Like Particle / genetics
  • Vaccines, Virus-Like Particle / immunology
  • Vaccines, Virus-Like Particle / metabolism
  • Virion / metabolism
  • Virus Assembly*


  • Capsid Proteins
  • Oncogene Proteins, Viral
  • Papillomavirus Vaccines
  • Vaccines, Virus-Like Particle
  • L1 protein, Human papillomavirus type 16