Viable chimaeric viruses confirm the biological importance of sequence specific maize streak virus movement protein and coat protein interactions.
BACKGROUND
A variety of interactions between up to three different movement proteins (MPs), the coat protein (CP) and genomic DNA mediate the inter- and intra-cellular movement of geminiviruses in the genus Begomovirus. Although movement of viruses in the genus Mastrevirus is less well characterized, direct interactions between a single MP and the CP of these viruses is also clearly involved in both intra- and intercellular trafficking of virus genomic DNA. However, it is currently unknown how specific these MP-CP interactions are, nor how disruption of these interactions might impact on virus viability.


RESULTS
Using chimaeric genomes of two strains of Maize streak virus (MSV) we adopted a genetic approach to investigate the gross biological effects of interfering with interactions between virus MP and CP homologues derived from genetically distinct MSV isolates. MP and CP genes were reciprocally exchanged, individually and in pairs, between maize (MSV-Kom)- and Setaria sp. (MSV-Set)-adapted isolates sharing 78% genome-wide sequence identity. All chimaeras were infectious in Zea mays c.v. Jubilee and were characterized in terms of symptomatology and infection efficiency. Compared with their parental viruses, all the chimaeras were attenuated in symptom severity, infection efficiency, and the rate at which symptoms appeared. The exchange of individual MP and CP genes resulted in lower infection efficiency and reduced symptom severity in comparison with exchanges of matched MP-CP pairs.


CONCLUSIONS
Specific interactions between the mastrevirus MP and CP genes themselves and/or their expression products are important determinants of infection efficiency, rate of symptom development and symptom severity.
van der Walt
Eric
E
Department of Molecular and Cell Biology, University of Cape Town, Cape Town, South Africa. eric.vanderwalt@kapabiosystems.com
Palmer
Kenneth E
KE
Martin
Darren P
DP
Rybicki
Edward P
EP
D036022:Capsid Proteins / Q000235:genetics / Q000378:metabolism*; D026762:Maize streak virus / Q000235:genetics / Q000472:pathogenicity*; D050296:Microbial Viability; D010935:Plant Diseases / Q000821:virology; D053830:Plant Viral Movement Proteins / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D011995:Recombination, Genetic; D012720:Severity of Illness Index; D003313:Zea mays
D036022:Capsid Proteins; D053830:Plant Viral Movement Proteins