Comparative analysis of the genome and host range characteristics of two insect iridoviruses: Chilo iridescent virus and a cricket iridovirus isolate

Abstract

The iridovirus isolate termed cricket iridovirus (CrIV) was isolated in 1996 from Gryllus campestris L. and Acheta domesticus L. (both Orthoptera, Gryllidae). CrIV DNA shows distinct DNA restriction patterns different from those known for Insect iridescent virus type 6 (IIV-6). This observation led to the assumption that CrIV might be a new species within the family Iridoviridae. CrIV can be transmitted perorally to orthopteran species, resulting in specific, fatal diseases. These species include Gryllus bimaculatus L. and the African migratory locust Locusta migratoria migratorioides (Orthoptera, Acrididae). Analysis of genomic and host range properties of this isolate was carried out in comparison to those known for IIV-6. Host range studies of CrIV and IIV-6 revealed no differences in the peroral susceptibility in all insect species and developmental stages tested to date. Different gene loci of the IIV-6 genome were analyzed, including the major capsid protein (274L), thymidylate synthase (225R), an exonuclease (012L), DNA polymerase (037L), ATPase (075L), DNA ligase (205R) and the open reading frame 339L, which is homologous to the immediate-early protein ICP-46 of frog virus 3. The average identity of the selected viral genes and their gene products was found to be 95n98 and 95n18 % at the nucleotide and amino acid level, respectively. These data led to the conclusion that CrIV and IIV-6 are not different species within the Iridoviridae family and that CrIV must be considered to be a variant and/or a novel strain of IIV-6.

Natural invertebrate hosts of iridoviruses (Iridoviridae)

“…Despite records of IIV infections from agriculturally and medically important species of insects, these viruses are considered to have little potential as agents of biological control due to the often low prevalence of patent disease and the broad host range displayed in laboratory tests (Ohba 1975, Henderson et al 2001, Jakob et al 2002. This has led to a lack of interest in the study of these viruses and a resulting paucity of information concerning their biology and survival in invertebrate populations.…”

Complete Genome Sequence of Lymphocystis Disease Virus Isolated from China

“…Some of the viral proteins that might be involved in virus-host interaction were also identified from LCDV-C ORFs by significant amino acid sequence homology, such as tumor necrosis factor receptor (ORF016L), ␤-hydroxysteroid dehydrogenase (ORF003R), membrane-bound metallopeptidase (ORF033R), histone-like transcription factor (ORF054R), ATPase (ORF080L, ORF209R, and ORF237L), transmembrane receptor (ORF058L), and caspases (ORF002L) ( Table 2). Just as for other sequenced iridoviruses (13,14,16,17,18,33), the majority of these enzymes for LCDV-C represent homologues of cellular enzymes involved in virus replication and transcription and are shared by all iridoviruses (Table 3). Since iridoviruses form a viromatrix in cytoplasm and since theirreplication,transcription,andnucleotidemetabolismmain- (42), they must establish their own replication and transcription machinery (18).…”

Diseases in insects produced for food and feed

“…Several other viruses have been found in crickets, for example Jakob et al (2002) isolated a cricket iridovirus (CrIV) from both Gryllus campestris and A. domesticus. This iridovirus CrIV could infect both A. domesticus and other orthopterans (G. campestris, G. bimaculatus and L. migratoria) and can even be fatal (Kleespies et al, 1999).…”