Negative regulation of the RTBV promoter by designed zinc finger proteins.

The symptoms of rice tungro disease are caused by infection by a DNA-containing virus, rice tungro bacilliform virus (RTBV). To reduce expression of the RTBV promoter, and to ultimately reduce virus replication, we tested three synthetic zinc finger protein transcription factors (ZF-TFs), each comprised of six finger domains, designed to bind to sequences between -58 and +50 of the promoter. Two of these ZF-TFs reduced expression from the promoter in transient assays and in transgenic Arabidopsis thaliana plants. One of the ZF-TFs had significant effects on plant regeneration, apparently as a consequence of binding to multiple sites in the A. thaliana genome. Expression from the RTBV promoter was reduced by approximately 45% in transient assays and was reduced by up to 80% in transgenic plants. Co-expression of two different ZF-TFs did not further reduce expression of the promoter. These experiments suggest that ZF-TFs may be used to reduce replication of RTBV and thereby offer a potential method for control of an important crop disease.