Transgenic apple expressing an antigenic protein of the human respiratory syncytial virus

A gene coding for the human respiratory syncytial virus (RSV)-F protein, driven by the constitutively expressed CaMV 35S promoter, was introduced into leaf tissues of apple, Malus×domestica Borkh. cv. Royal Gala, via Agrobacterium-mediated transformation. Two putative transgenic lines were identified, and the presence of the RSV-F gene was confirmed by polymerase chain reaction (PCR). A total of 25 plants from these different transgenic events were successfully rooted, acclimatized, and transferred to the greenhouse. Stable integration of the transgene was confirmed and transgene copy number was determined by DNA gel blot analysis. Expression of the npt-II selectable marker and RSV-F was determined using reverse-transcription polymerase chain reaction (RT-PCR). Furthermore, enzyme-linked immunosorbent assay (ELISA) revealed varying levels of protein expression of the RSV-F transgene, ranging from 0 to 20 μg/g tissue. This is a first step in an effort to assess the efficacy of using apple for developing a plant-based vaccine against RSV.