Maize Streak Virus

Abstract

Maize streak virus (MSV) is the type member of the genus Mastrevirus of the family Geminiviridae and the causal agent of maize streak disease (MSD), the most important viral disease of maize in sub-Saharan Africa. The virus remains largely uncontrolled in most parts of the continent and in epidemic years it contributes to widespread yield losses and famine. Nine major MSV strains have been identified so far, of which only the MSV-A strain produces economically important infections in maize. Apart from maize, however, these various MSV strains infect over 80 other grass species including wheat, barley, and rye. The epidemiological complexity of MSD is in stark contrast with the genomic simplicity of MSV. The MSV genome contains two intergenic regions involved in replication and regulation of gene expression and encodes only four proteins: two proteins, Rep and RepA, involved in genome replication and regulation of host and/or virus gene expression; and two proteins, a movement and a coat protein, involved in systemic spread and encapsidation of viral DNA within characteristic geminate particles. Control of the virus via insecticidal targeting of its leafhopper vector and widespread use of resistant maize varieties derived through genetic engineering and/or breeding approaches will substantially improve African food security.