Role of Virion and Helper Component in Regulating Aphid Transmission of Tobacco Etch Virus

Abstract

Three isolates of tobacco etch virus (TEV) were either highly, poorly or nontransmissible by aphids (HAT, PAT or NAT, respectively) from infected tobacco plants. Purified virus of these isolates acquired through membranes was transmitted with high, intermediate and low efficiency, respectively, in the presence of helper component (HC). Thus, intrinsic differences in properties of the virions, most likely differences in the coat proteins, appear to be responsible for differences in transmissibility. HC could be extracted from plants infected with each of the 3 isolates, and HC activity was highest from PAT-infected plants, suggesting that absence or deficiency of HC was not responsible for differences in transmissibility. Since aphids given access first to HC and then to infected plants were able to transmit the NAT isolate, and transmitted the PAT isolate with increased frequency, a role for HC in regulating the efficiency of aphid transmission from plants cannot be ruled out.