Tobacco mosaic virus infection of transgenic Nicotiana tabacum plants is inhibited by antisense constructs directed at the 5' region of viral RNA.

Antisense (AS) versions of two 51-nucleotide (nt) sequences near the 5' end of tobacco mosaic virus (TMV) RNA have been shown to inhibit in vitro translation of the adjacent gene that encodes both the 126- and 183-kDa proteins. These DNA fragments have been cloned into the binary vector, pMON530, such that either the nopaline synthase (Nos) promoter or cauliflower mosaic virus (CaMV) 35S RNA promoter is used to drive synthesis of the corresponding sense and AS RNAs. Transgenic Nicotiana tabacum cv. Xanthi nn plants containing these constructs were challenged with TMV. Plants expressing the AS orientation of a 51-nt TMV leader sequence, under the control of the CaMV 35S promoter, were found to be resistant to infection when inoculated with up to 100 times the concentration of TMV which produced severe infections in control plants. Systemic accumulation of TMV RNA and progeny virus was diminished 15 to 30-fold in these plants. Accumulation of the viral coat protein was diminished 6 to 7-fold implying a selective inhibition of TMV replication.