An interspecies hybrid RNA virus is significantly more virulent than either parental virus

• Published in: Proceedings of the National Academy of Sciences - PNAS 1996-07, Vol.93 (15), p.7470-7474
• Main Authors: Ding, S.W. (University of Adelaide, Glen Osmond, SA, Australia.), Shi, B.J, Li, W.X, Symons, R.H
• Format: Article
• Language: English
• Subjects: AMARANTHACEAE; Base Sequence; Biochemistry; cucumber mosaic virus; CUCUMOVIRUS; Cucumovirus - genetics; Cucumovirus - pathogenicity; CUCUMOVIRUS DEL MOSAICO DEL PEPINO; CUCUMOVIRUS MOSAIQUE DU CONCOMBRE; DNA Primers; EXPERIMENTACION IN VIVO; EXPERIMENTATION IN VIVO; GENE; GENES; GENOMAS; GENOME; Genome, Viral; Genomes; HIBRIDACION; HIBRIDOS; HYBRIDATION; HYBRIDE; Hybridity; Hybridization, Genetic; INFECCION EXPERIMENTAL; INFECTION EXPERIMENTALE; Infections; Molecular Sequence Data; Mutagenesis, Site-Directed; Nicotiana; NICOTIANA TABACUM; Open Reading Frames; PATOGENICIDAD; Plant Diseases; Plants - virology; Plants, Toxic; Plasmids; Polymerase Chain Reaction; POUVOIR PATHOGENE; PROTEINAS; PROTEINE; Proteins; PROTOPLASTE; PROTOPLASTOS; Protoplasts; REPLICACION; REPLICATION; Ribonucleic acid; RNA; RNA, Viral - genetics; SINTOMAS; SOLANACEAE; Species Specificity; STELLARIA; SYMPTOME; Symptoms; tomato aspermy virus; Transfection; Vegetables; Virulence; VIRUS; VIRUS DE LAS PLANTAS; VIRUS DES VEGETAUX; Viruses
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.93.15.7470

Cucumber mosaic cucumovirus (CMV) infects a very wide range of plant species (1000 species). We recently demonstrated that a previously undescribed gene (2b) encoded by RNA 2 of the tripartite RNA genome of CMV is required for systemic virus spread and disease induction in its hosts. Herein we report that when this CMV gene is replaced by its homologue from tomato aspermy cucumovirus (TAV), the resultant hybrid virus is significantly more virulent, induces earlier onset of systemic symptoms, and accumulates to a higher level in seven host species from three families than either of the parents. Our results indicate that CMV and the TAV 2b protein interact synergistically despite the fact that no synergism occurs in double infections with the two parental viruses. To our knowledge, this is the first example of an interspecific hybrid made from plant or animal RNA viruses that is more efficient in systemic infection of a number of hosts than the naturally occurring parents. As CMV and the hybrid virus accumulated to a similar level in the infected tobacco protoplasts, the observed synergistic responses most likely resulted from an increased efficacy of the hybrid virus in systemic spread in host plants provided by the TAV 2b protein. The relevance of our finding to the application of pathogen-derived resistance is discussed