Return to Bursary Topic -- Biological Control- Introduction
- Taxonomy
- Morphology
- Genome Structure
- Replication
- Gene Expression
- Pathogenesis
The family Iridoviridae contains a diverse array of large icosahedral viruses that replicate in the cytoplasm of infected cells. The word Iridoviridae is derived from Iris who was the Greek goddess of the rainbow. This is due to the "rainbow like" iridescence observed in heavily infected insects and pelleted samples of invertebrate iridoviruses.
Larvae of the New Zealand, grass grub Costelytra zealandica displaying blue colouration of the hindgut due to iridovirus infection. The other common NZ pasture pest, porina (or Wiseana cervinata), also can be infected with virus and can give similiar colourations.
Pellet of purified iridescent virus in the bottom a centrifuge tube
This iridescence was used to detect the first iridovirus when Claude Rivers, in March of 1954, discovered crane fly larvae (Tipula spp) glowing with patches of blue colouration. Iridoviruses have since been isolated from both invertebrate and non-mammalian vertebrate hosts (like fish and frogs). A common feature of most of these hosts is the aquatic or moist environment in which they are found. Iridoviruses have received attention because of the problems they pose to aquacultural practices and because of their potential use in the biological control of insect pests. At the Microbiology Department, University of Otago, a group of scientists are exporing the possible use of these viruses to control porina and grass grub. At this stage they are trying to understand the biology of this virus and the rest of this website is concerned with work currently underway using a cell tissue culture system.
Virus crystal packing of virus particles within an infected insect. This packing gives rise to the blue iridescent colour.
Tissue culture cell showing cytoplasmic localisation of assembling Wiseana iridescent virus ( from porina) N= nucleus, VC = viroplasmic centre
© WWK 1998 (Webby, Watson & Kalmakoff)
University of Otago, Dunedin, New Zealand