In vitro association between the helper component-proteinase of zucchini yellow mosaic virus and cuticle proteins of Myzus persicae.

Potyviruses, as typical non-persistently transmitted viruses, are carried within the stylets of aphids. Cuticle proteins (CuPs), which are a major component of the insect cuticle, were examined for in vitro binding to the potyviral helper component-proteinase (HC-Pro). Proteins in 8 M urea extracts from Myzus persicae were separated by SDS-PAGE, electroblotted onto membranes and identified as CuPs by using specific antibodies to M. persicae CuP. Blotted M. persicae protein extracts were overlaid with two HC-Pros, differing by the presence of K or E in the KLSC domain. The HC-Pro with KLSC, known to assist transmission, was found to bind M. persicae proteins, whereas the HC-Pro with ELSC, being deficient in assisting transmission, did not. To identify CuPs that react with HC-Pro, protein extracts were separated by two-dimensional gel electrophoresis. Nine proteins reacting with HC-Pro were sequenced by mass spectrometry. Sequences of peptides in four proteins, of molecular masses between 22 and 31 kDa, were identified as CuPs according to comparison with sequences in GenBank. The putative CuPs from M. persicae that bind HC-Pro are potentially of interest in locating receptors for virions bound to HC-Pro in aphids' stylets.