Abstract: Natural infection of plants by virus occurs commonly and often by two or more plant viruses. Those co-infected phenomenon can result in various effects, such as synergism, antagonism or coexistence. The relatively well-known antagonism is cross-protection, also referred to as super-infection exclusion. This type of interaction occurs when a previous infection with one virus prevents or interferes with subsequent infection by a homologous secondary virus. Most reports of antagonism are of different viruses of the same genus or of different strains of the same virus. Earlier studies reviewed the possible mechanisms of cross protection among virus of the same strains are presented as follows:protein-mediated resistance, the basal immune mechanisms of host plants, defensive reactions mediated by RNA silencing. In addition, the function of various viral suppressors of RNA silencing (VSRs) has important roles in the interactions between viruses in mixed infections. It has been suggested that viral VSRs have important roles in tissue invasion patterns in mixed virus infections. However, none of them can fully explain this phenomenon and the mechanism of cross-protection remains unclear. This review outlines the current state of knowledge concerning the molecular mechanisms behind antagonism between plant viruses. Moreover, the review briefly outlines the past and present attempts to utilize antagonistic interactions among viruses to protect crop plants against destructive diseases.

Key words: Plant viruses, Co-infection, Interaction, Cross-protection, Antagonism

CLC Number: 

• Q945.8