Virus-induced disease: altering host physiology one interaction at a time.

Virus infections are the cause of numerous plant disease syndromes that are generally characterized by the induction of disease symptoms such as developmental abnormalities, chlorosis, and necrosis. How viruses induce these disease symptoms represents a long-standing question in plant pathology. Recent studies indicate that symptoms are derived from specific interactions between virus and host components. Many of these interactions have been found to contribute to the successful completion of the virus life-cycle, although the role of other interactions in the infection process is not yet known. However, all share the potential to disrupt host physiology. From this information we are beginning to decipher the progression of events that lead from specific virus-host interactions to the establishment of disease symptoms. This review highlights our progress in understanding the mechanisms through which virus-host interactions affect host physiology. The emerging picture is one of complexity involving the individual effects of multiple virus-host interactions.