The helper component-proteinase of cowpea aphid-borne mosaic virus

Cowpea aphid-borne mosaic potyvirus causes severe yield losses in cowpea, an important legume crop in semi-arid regions of Africa. We have elucidated the genomic sequence of the virus and subsequently focused our attention on the so-called helper component-proteinase (HC-Pro), a virus-encoded multifunctional protein with roles in different steps of the virus life cycle. Our study has shed more insight into some of the molecular properties of this protein. We have shown that HC-Pro is able to shut down host defense responses, and this puts HC-Pro at the core of the success of CABMV as a pathogen. The phenomenon also seems to benefit other viruses as they accumulate to higher levels and elicit enhanced symptoms in the presence of HC-Pro. On the other hand, we have found that the host does manifest an ability to counter the deleterious effects of HC-Pro. A full understanding of the molecular basis of this contest would enable the design of effective new strategies to protect plants from virus infections.