Defective or effective? Mutualistic interactions between virus genotypes

• Published in: Proceedings of the Royal Society. B, Biological sciences Vol. 270; no. 1530; pp. 2249 - 2255
• Main Authors: Lopez-Ferber, M, Simon, O, Williams, T, Caballero, P
• Format: Journal Article
• Language: English
• Published: England The Royal Society 07.11.2003; Royal Society, The
• Subjects: Animals; Bioassay; Defective Genotypes; Defective Viruses - genetics; Disease transmission; DNA Restriction Enzymes; Electrophoresis, Agar Gel; Genotype; Genotypes; Infections; Insect genetics; Insect larvae; Lepidoptera; Life Sciences; Mutualistic Interactions; Nucleopolyhedrovirus; Nucleopolyhedrovirus - genetics; Nucleopolyhedrovirus - pathogenicity; Parasite hosts; Pathogenicity; Polymerase Chain Reaction; Selection, Genetic; Spodoptera - virology; Symbiosis; Virions; Viruses; mutualistic interactions; pathogenicity; defective genotypes; nucleopolyhedrovirus; Lepidoptera
• ISSN: 0962-8452; 1471-2954
• DOI: 10.1098/rspb.2003.2498

Defective viruses lack genes essential for survival but they can co-infect with complete virus genotypes and use gene products from the complete genotype for their replication and transmission. As such, they are detrimental to the fitness of complete genotypes. Here, we describe a mutualistic interaction between genotypes of an insect baculovirus (nucleopolyhedrovirus of Spodoptera frugiperda (Lepidoptera)) that increases the pathogenicity of the viral population. Mixtures of a complete genotype able to be transmitted orally and a deletion mutant unable to be transmitted orally resulted in a phenotype of increased pathogenicity. Because the infectiousness of mixed genotype infections was greater than that of single genotype infections, we predict that the transmissibility of mixed genotype occlusion bodies will be greater than that of any of their single genotype components. Such interactions will be subject to frequency-dependent selection and will influence the impact of these viruses on insect population dynamics and their efficacy as biological insecticides.