Our previous study identified that the RepA protein encoded by the oat dwarf virus (ODV) was responsible for inducing a strong hypersensitive response (HR) during the virus infection in non-host tobacco plants. However, little was known about the molecular mechanism of the RepA-elicited HR. Here, a RING-finger protein, which is described as NbRFP1 and is mainly located in the cytoplasm and nucleus inNicotiana benthamianacells, was confirmed to interact with RepA. In addition, the accumulation level ofNbRFP1inN. benthamianaleaves was enhanced by either ODV infection or by only RepA expression. The knockdown ofNbRFP1by a TRV-mediated virus-induced gene silencing markedly delayed the ODV or RepA-elicited HR. By contrast, the overexpression ofNbRFP1inN. benthamianaconferred enhanced resistance to ODV infection and promoted RepA-induced HR. Further mutation analysis showed that a RING-finger domain located in NbRFP1 plays important roles in modulating RepA-induced HR, as well as in mediating the interaction between NbRFP1 and RepA.