Submitted to: Journal of Virology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 7/7/2006
Publication Date: 9/1/2006
Citation: Delhon, G., Tulman, E., Afonso, C.L., Lu, Z., Becnel, J.J., Moser, B.A., Kutish, G.F., Rock, D.L. 2006. Genome of invertebrate iridescent virus 3 (mosquito iridescent virus). Journal of Virology. 80(17):8439-8449. Interpretive Summary: A naturally occurring mosquito iridescent virus (MIV) that kills mosquitoes has been isolated by ARS scientists. This new virus is designated as "Regular Mosquito Iridescent Virus" (RMIV) with strains isolated from a number of important mosquito species. This report presents the complete genomic sequence of RMIV with an analysis of its relationship to other iridescent viruses. This fundamental information contributes to our basic understanding of these mosquito pathogenic viruses and will enable a more complete evaluation to understanding how they might be exploited to control mosquitoes that vector deadly diseases of man and animals.
Technical Abstract: 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 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 3 (IIV-3), also known as mosquito iridescent virus, currently the sole member of the genus Chloriridovirus. Approximately 20% of the 191 Kbp IIV-3 genome was repetitive DNA, with DNA repeats localized in 16 apparently non-coding regions. Of the 126 predicted IIV-3 genes, 27 shared homologues in all currently sequenced IVs, suggesting a genetic core for the family Iridoviridae. Fifty-two IIV-3 genes, including those encoding for 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, suggesting these genes 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 poxviral MutT-like proteins. The absence of genes present in other IVs, including IIV-6, lack of colinearity with any sequenced IV, 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.