title: Persistence of an occlusion-negative recombinant nucleopolyhedrovirus in Trichoplusia ni indicates high multiplicity of cellular infection.
abstract: We use data from the serial passage of co-occluded recombinant Autographa californica nuclear polyhedrosis virus (AcMNPV) to estimate the viral multiplicity of infection of cells within infected insects. Co-occlusion, the incorporation of wild-type and mutant virus genomes in the same occlusion body, has been proposed as a strategy to deliver genetically modified viruses as insecticides in a way that contains their spread in the environment. It may also serve as a means whereby naturally occurring mutant forms of NPVs can be maintained in a stable polymorphism. Here, a recombinant strain of AcMNPV was constructed with a deletion of its polyhedrin gene, rendering it incapable of producing occlusion bodies (i.e., occlusion negative). This was co-occluded with wild-type AcMNPV and used to infect fifth-instar Trichoplusia ni larvae. The fate of both genotypes was monitored over several rounds of insect infection. Levels of the occlusion-negative virus genome declined slowly over successive rounds of infection. We applied these data to a model of NPV population genetics to derive an estimate of 4.3 +/- 0.3 viral genomes per occlusion body-producing cell.
authors.affiliation: Department of Biology, Imperial College of Science, Technology, and Medicine, London SW7 2AZ, United Kingdom.
authors.forename: J C
authors.initials: JC
authors.lastname: Bull
authors.forename: H C
authors.initials: HC
authors.lastname: Godfray
authors.forename: D R
authors.initials: DR
authors.lastname: O'Reilly
mesh_terms: D000818:Animals; D017353:Gene Deletion; D005818:Genetic Engineering / Q000379:methods; D007915:Lepidoptera / Q000821:virology*; D017924:Nucleopolyhedroviruses / Q000187:drug effects / Q000235:genetics / Q000472:pathogenicity* / Q000502:physiology*; D015388:Organelles / Q000235:genetics*; D010572:Pest Control, Biological; D011995:Recombination, Genetic; D014779:Virus Replication