In search of ways that will make HPV vaccine production cheaper, scientists from Spain and France developed transgenic tobacco lines expressing the HPV protein L1. L1 is a major structural protein in the viral capsid (protein shell) that aggregates to form non-infectious virus-like particles (VLP). Since it can induce both humoral and cellular responses, VLPs are prime candidates in the production of HPV vaccines.

The viral gene coding for L1 was specifically expressed in the chloroplasts. Chloroplast transformation offers several advantages such as transgene containment, absence of gene silencing and high recombinant protein yield. High L1 expression, equivalent to 24 percent of the total soluble protein, was achieved in mature GM plants. Immunization experiments have shown that the recombinant protein and the resulting VLPs are highly immunogenic.

The article published by the Plant Biotechnology Journal is available at http://www.blackwell-synergy.com/doi/abs/10.1111/j.1467-7652.2008.00338.x