Aphid-borne viruses · Blocking the transmission of aphid-borne plant viruses

Blocking the transmission of aphid-borne plant viruses

The concept developed in this project has the end goal of developing a novel disease control strategy: blocking the transmission of non-circulative aphid-borne plant viruses. The basic idea is that virus binding to vectors can be disrupted by molecules that compete for receptors on the stylet of aphid vectors, i.e. the retention site of such viruses within vectors. These molecules (antibodies or peptides) would essentially compete with the viruses for receptors; if those are masked the viruses are not capable of binding to vectors, effectively disrupting transmission and limiting disease spread. Therefore, experiments were performed to test this hypothesis using widespread aphid vector species and economically important plant viruses. A large set of experiments was performed to initially improve the experimental conditions and specific details of these assays, so that the central concept proposed here could be tested adequately. Those included optimization of virus and protein concentrations used during tests, components of artificial diets, as well as buffers used. Experiments performed to test if virus antibodies could block transmission failed to generate positive results, even if the concentration of virus (CMV, cucumovirus) was order of magnitude lower than that of its respective antibodies. Initial experiments in which blocking of potyviruses and caulimoviruses with other proteins and viruses were also not successful. However, all results obtained so far strongly indicate that a non-structural protein encoded by one virus (P2, CaMV), negatively affects the transmission of another virus (CMV) by aphid vectors. A series of experiments were performed to address this finding, and all in vitro assays support this observation. This is a very exciting result. It strongly suggests that P2-CaMV and CMV, which are very different viruses, compete for the same receptor or specific site on the cuticular surface of the stylets of aphid vectors. In addition, it indicates that it may be possible to disrupt the transmission of both viruses using molecular determinants of transmission required by either one. To conclusively demonstrate that P2-CaMV disrupts the aphid transmission of CMV, we are now collaborating with a colleague in Madrid, Spain, who can monitor specific aphid feeding behaviors, so that we can test this hypothesis using plants rather than artificial diets, as has been done so far. Those results are pending. If these final results demonstrate that blocking is feasible, these findings could serve as the basis for the development of new plant disease control strategies. Plant diseases caused by insect-transmitted pathogens are of great importance to agriculture worldwide. In fact, epidemics of such diseases have led to famine in African countries and severe economic losses in Europe, North America and elsewhere. Despite their obvious importance, these diseases are primarily studied by focusing on the pathogen or vector alone, rather than on the interactions between pathogen and vector required for disease spread in the field. Consequently, control strategies usually focus on pesticide applications to reduce vector populations; these approaches are costly, unsustainable and have negative environmental impacts. Therefore, the management of vector-borne plant pathogens would greatly benefit from the successful development of this concept.

Data: CORDIS, © European Union