Although a number of aphid proteins that bind luteovirids have been identified, the molecular details of virus movement in aphids are not well understood. Due to the paucity of molecular tools for the study of aphids, most virus-binding proteins have been identified using proteomics approaches. In Sitobion avenae, four 2-D gel spots were differentially expressed between parthenogenetically-reproducing F1 clones that differed in their vectoring capacity for two isolates of the species Barley yellow dwarf virus (BYDV)-PAV [19] . Two proteins from head tissues of S. avenae were identified as potential receptors for BYDV-MAV based on virus overlay and 2-D immunoblot assays [5] . Other studies progressed beyond 2-D gel spot patterns to use mass spectrometry (MS) to investigate the identity of aphid proteins associated with virus transmission [9, 10, 20] in effort to link the protein function to vector biology. Membrane-associated actin, rack-1, and GAPDH-3 were identified to interact with a wild-type isolate of Beet western yellows virus (BWYV). Actin and GAPDH-3, but not rack-1, also interacted with two BWYV RTP mutants displaying a reduction in aphid transmission ability [20] indicating either (a) their assay for virus binding does not reflect the in vivo functions of these interactions in aphids, or (b), that these RTP mutants still retain the interaction interface for binding with these aphid proteins. Cyclophilin and a luciferase homologue were identified from the greenbug aphid Schizaphis graminum as binding to CYDV-RPV. These proteins were also differentially expressed among different S. graminum F2 genotypes with different CYDV-RPV vectoring capacity [9, 10] . Intriguingly, all studies investigating proteomic differences of aphid F1 [19] or F2 progeny genotypes [9, 10, 19] reported the differences between vectors and non-vectors were not related to gross changes in protein expression levels. Instead, vectoring capacity was associated with a small shift in the isoelectric point of only a small number of proteins, indicating that the control of luteovirid transmission in multiple aphid species was via the expression of allelic variants of proteins that either differentially bind to the virion or participate in the various steps of the virus transmission pathways.