ASSOCIATION OF POTYVIRUS HELPER COMPONENT PROTEIN WITH VIRIONS AND THE CUTICLE LINING THE MAXILLARY FOOD CANAL AND FOREGUT OF AN APHID VECTOR

Transmission electron microscopy and immunogold labeling were used to study the role of the helper component protein (HC) that is required f or the transmission of potyviruses by aphids. Purified tobacco etch vi rus (TEV) and tobacco vein mottling virus (TVMV) were fed to the aphid vector, Myzus persicae. either with or without purified HC. In sectio ns of aphids that fed on a mixture of purified virions and HC, filamen tous viruslike particles (VLP) embedded in a matrix material were asso ciated with the epicuticle, predominantly in the maxillary food canal but also in the precibarium and cibarium of the foregut. No VLP were f ound at any of these sites in aphids that fed on purified virions with out HC. Immunogold labeling demonstrated that the VLP are TEV or TVMV virions and that HC is associated with virions and with the epicuticle lining the food canal and foregut. These results support the hypothes is that HC is directly involved in binding or attachment of virions to the cuticle of the maxillary food canal and foregut of aphid vectors.