For example, a protein found in pokeweed, pokeweed antiviral protein . The problem with using PIP as an antiviral agent is that PIP is toxic to most plants when expressed as a transgene. One way around this problem is to place the RIP coding sequence under the control of a virus inducible promoter. The coat protein promoter of ACMV is inactive unless a viral transactivator protein, AC2, is present. Inoculation of dianthin transgenic plants with ACMV causes local expression of AC2 in the first few infected cells, induction of the dianthin gene and localized cell death.
Cell death prevents spread of the virus from the original infected cells to neighboring cells.
Resistance to geminivirus infection by virus-induced expression of dianthin in transgenic plants. Virology 220, 119-227. A geminivirus induces expression of a host DNA synthesis protein in terminally differentiated plant cells. Plant Cell 7, 705-719.