Recombinant Potato virus Y (PVY) strains (PVY^N:O, PVY^NTN) have replaced the long dominant ordinary strain (PVY^O) in the US potato crop. Transmission bias by aphid vectors is contributing; aphids preferentially transmit the recombinant strains when acquired sequentially with the ordinary strain. To understand the mechanisms behind this, we separated purified virus and active helper component proteins (HC), mixed them in homologous and heterologous combinations, and then fed them to aphids. HCs showed strain-specific properties. Mixtures of PVY^O HC with either recombinant virus, PVY^N:O or PVY^NTN, resulted in efficient transmission. PVY^N:O HC also facilitated the transmission of PVY^O and PVY^NTN, albeit at reduced efficiency. PVY^NTN HC failed to facilitate transmission of either PVY^O or PVY^N:O. To better understand transmission bias towards specific HCs, mixtures of two purified viruses were combined with a single HC and fed to aphids. In these experiments both viruses were transmitted at higher efficiencies than in the single virus treatments when mixed with PVY^O HC or PVY^N:O HC. Treatment combinations mixed with PVY^NTN HC resulted in zero transmission. In this case, non-specificity could be due to factors of virus or HC concentration affecting virus binding and release efficiency. Ongoing research is evaluating transmission using serial dilutions of purified virus mixed with similar amounts of HCs.