Invertebrate Iridescent Viruses

Williams, Trevor

doi:10.1007/978-1-4615-5341-0_2

Cited by 36 publications

(44 citation statements)

References 173 publications

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“…In contrast to previous reports, IIV-3 repeated sequences were extensive (20% of the genome), resembling IIV-9 and IIV-16, in which 25% and 39% of the genomes, respectively, are made up of repetitive DNA (10,58,89). Although late transcription has been detected from IIV-9 repeated DNA regions, the role of IV DNA repeats is unknown (59).…”

Section: Resultscontrasting

confidence: 47%

“…IIV-3 is characterized by its restricted host range (mosquitoes [Diptera]) and relatively large particle size (180 nm) (17,90). In contrast, IIVs of the Iridovirus genus have been isolated from diverse hosts of the orders Diptera, Lepidoptera, Hemiptera, and Coleoptera and are approximately 120 nm in diameter (89). Iridovirus species include IIV-1, the first reported IV; IIV-6, the type species of the genus; and several tentative species which remain to be fully characterized (25,89,94).…”

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confidence: 99%

“…In contrast, IIVs of the Iridovirus genus have been isolated from diverse hosts of the orders Diptera, Lepidoptera, Hemiptera, and Coleoptera and are approximately 120 nm in diameter (89). Iridovirus species include IIV-1, the first reported IV; IIV-6, the type species of the genus; and several tentative species which remain to be fully characterized (25,89,94). Notably, IIV-6 can also infect mosquitoes but causes only sublethal (covert) infections and reduced fitness in Aedes aegypti relative to noninfected conspecifics (55).…”

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confidence: 99%

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Genome of Invertebrate Iridescent Virus Type 3 (Mosquito Iridescent Virus)

Delhon

Tulman

Afonso

et al. 2006

J Virol

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Iridoviruses (IVs) are classified into five genera: Iridovirus and Chloriridovirus, whose members infect invertebrates, and Ranavirus, Lymphocystivirus, and Megalocytivirus, whose members infect vertebrates. Until now, Chloriridovirus was the only IV genus for which a representative and complete genomic sequence was not available. Here, we report the genome sequence and comparative analysis of a field isolate of Invertebrate iridescent virus type 3 (IIV-3), also known as mosquito iridescent virus, currently the sole member of the genus Chloriridovirus. Approximately 20% of the 190-kbp IIV-3 genome was repetitive DNA, with DNA repeats localized in 15 apparently noncoding regions. Of the 126 predicted IIV-3 genes, 27 had homologues in all currently sequenced IVs, suggesting a genetic core for the family Iridoviridae. Fifty-two IIV-3 genes, including those encoding DNA topoisomerase II, NAD-dependent DNA ligase, SF1 helicase, IAP, and BRO protein, are present in IIV-6 (Chilo iridescent virus, prototype species of the genus Iridovirus) but not in vertebrate IVs, likely reflecting distinct evolutionary histories for vertebrate and invertebrate IVs and potentially indicative of genes that function in aspects of virus-invertebrate host interactions. Thirty-three IIV-3 genes lack homologues in other IVs. Most of these encode proteins of unknown function but also encode IIV3-053L, a protein with similarity to DNA-dependent RNA polymerase subunit 7; IIV3-044L, a putative serine/threonine protein kinase; and IIV3-080R, a protein with similarity to poxvirus MutT-like proteins. The absence of genes present in other IVs, including IIV-6; the lack of obvious colinearity with any sequenced IV; the low levels of amino acid identity of predicted proteins to IV homologues; and phylogenetic analyses of conserved proteins indicate that IIV-3 is distantly related to other IV genera.

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Section: Resultscontrasting

confidence: 47%

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confidence: 99%

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confidence: 99%

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Genome of Invertebrate Iridescent Virus Type 3 (Mosquito Iridescent Virus)

Delhon

Tulman

Afonso

et al. 2006

J Virol

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“…This is in line with previous observations on the low peroral infectivity of these viruses (Williams, 1998). This indicates that acquisition of infection by feeding on contaminated foliage, the principal route of infection for most insect DNA viruses, is probably negligible for transmission of IIV in S. frugiperda.…”

Section: Experiments 5: Transmission By Cannibalism In the Fieldsupporting

confidence: 80%

Costs of cannibalism in the presence of an iridovirus pathogen ofSpodoptera frugiperda

Williams

Hernández

2006

Ecological Entomology

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Abstract. 1. The costs of cannibalism were examined in larvae of Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae) in the presence of conspecifics infected by a lethal invertebrate iridescent virus (IIV). The hypothesis of a positive correlation between insect density and the likelihood of disease transmission by cannibalism was examined in laboratory microcosms and a field experiment.2. Transmission was negligible following peroral infection of early instars with purified virus suspensions or following coprophagy of virus-contaminated faeces excreted by infected insects. In contrast, 92% of the insects that predated infected conspecifics acquired the infection and died prior to adult emergence in the laboratory. Diseased larvae were more likely to be victims of cannibalism than healthy larvae.3. The prevalence of cannibalism was density dependent in laboratory microcosms with a low density (10 healthy insects þ one infected insect) or high density (30 healthy insects þ one infected insect) of insects, and field experiments performed on maize plants infested with one or four healthy insects þ one infected insect.4. Cannibalism in the presence of virus-infected conspecifics was highly costly to S. frugiperda; in all cases, insect survival was reduced by between & 50% (laboratory) and & 30% (field) in the presence of the pathogen. Contrary to expectations, the prevalence of disease was not sensitive to density because cannibalism resulted in self-thinning. As infected individuals are consumed and disappear from the population, the prevalence of disease will be determined by the timescale over which transmission can be achieved, and the rate at which individuals that have acquired an infection become themselves infectious to conspecific predators.

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“…These viruses have been isolated from insects including Lepidoptera, Coleoptera, Orthoptera, and Diptera and terrestrial isopods (Crustacea) and are generally associated with hosts that dwell in damp or aquatic habitats (Williams, 1998).…”

Section: Introductionmentioning

confidence: 99%

Parasitoid-mediated transmission of an iridescent virus

López

Rojas

Vandame

et al. 2002

Journal of Invertebrate Pathology

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We examined the interaction between an invertebrate iridescent virus (IIV) isolated from Spodoptera frugiperda (J.E. Smith) and the solitary ichneumonid endoparasitoid Eiphosoma vitticolle Cresson. In choice tests, parasitoids examined and stung significantly more virus infected than healthy larvae, apparently due to a lack of defense reaction in virus infected hosts. Parasitoid-mediated virus transmission was observed in 100% of the female parasitoids that stung a virus infected host in the laboratory. Each female parasitoid transmitted the virus to an average (AESE) of 3:7 AE 0:3 larvae immediately after stinging an infected larva. Caged field experiments supported this result; virus transmission to healthy larvae only occurred in cages containing infected hosts (as inoculum) and parasitoids (as vectors). The virus was highly detrimental to parasitoid development because of premature host death and lethal infection of the developing endoparasitoid. Female parasitoids that emerged from virus infected hosts did not transmit the virus to healthy hosts. We suggest that the polyphagous habits of many noctuid parasitoids combined with the catholic host range of most IIVs may represent a mechanism for the transmission of IIVs between different host species in the field.

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Invertebrate Iridescent Viruses

Cited by 36 publications

References 173 publications

Genome of Invertebrate Iridescent Virus Type 3 (Mosquito Iridescent Virus)

Genome of Invertebrate Iridescent Virus Type 3 (Mosquito Iridescent Virus)

Costs of cannibalism in the presence of an iridovirus pathogen ofSpodoptera frugiperda

Parasitoid-mediated transmission of an iridescent virus

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