Genomic Sequence of Heliothis virescens Ascovirus 3g Isolated from Spodoptera exigua

Abstract

dHeliothis virescens ascovirus 3a (HvAV-3a), a member of the family Ascoviridae, has the highest diversity among ascovirus species that have been reported in Australia, Indonesia, China, and the United States. To understand the diversity and origin of this important ascovirus, the complete genome of the HvAV Indonesia strain (HvAV-3g), isolated from Spodoptera exigua, was determined to be 199,721 bp, with a G؉C content of 45.9%. Therefore, HvAV-3g has the largest genome among the reported ascovirus genomes to date. There are 194 predicted open reading frames (ORFs) encoding proteins of 50 or more amino acid residues. In comparison to HvAV-3e reported from Australia, HvAV-3g has all the ORFs in HvAV-3e with 6 additional ORFs unique to HvAV-3g, including 1 peptidase C26 gene with the highest identity to Drosophila spp. and 2 gas vesicle protein U (GvpU) genes with identities to Bacillus megaterium. The five unique homologous regions (hrs) and 25 baculovirus repeat ORFs (bro) of HvAV-3g are highly variable.

Genome sequence and organization analysis of Heliothis virescens ascovirus 3f isolated from a Helicoverpa zea larva

“…The HvAV-3f genome size was slightly smaller than the HvAV-3g genome, but it is still currently the second largest ascovirus genome described (Huang et al, 2012b). A genomic map showing the organization of the ORFs longer than 210 nucleotides (nt) in the HvAV3f genome is presented in Fig.…”

“…For example, the genomes of SfAV-1a, TnAV-6a, HvAV3e, HvAV-3g and DpAV-4a showed 7, 3, 23, 25, and 12 bro ORFs, respectively (Asgari et al, 2007;Bigot et al, 2009;Huang et al, 2012b). HvAV-3f contained 29 bro genes that encode from 77 to 517 aa residues (Fig.…”

“…Based on virion morphology, DNA sequence information, host range and tissue tropism, five ascovirus species have been recognized by the International Committee on Taxonomy of Viruses, which are consisting of Spodoptera frugiperda ascovirus 1a (SfAV-1a), Trichoplusia ni ascovirus 2a (TnAV-2a), Heliothis virescens ascovirus 3a (HvAV-3a), and Diadromus pulchellus ascovirus 4a (DpAV-4a) and Trichoplusia ni ascovirus 6a (ex-TnAV-2c) (Bigot et al, 2011). Eighteen isolates or strains belonging to four ascovirus species have been reported in the world (Bigot et al, 2011;Huang et al, 2012a), in which five ascovirus isolates genomes that are SfAV-1a, TnAV-6a (Trichoplusia ni ascovirus 6a, previously named at its discovery TnAV-2c (Wang et al, 2006)), HvAV-3e, HvAV-3g, and DpAV-4a have been sequenced (Wang et al, 2006;Bideshi et al, 2006;Asgari et al, 2007;Bigot et al, 2009;Huang et al, 2012b). All these reported genomes have a double-stranded circular DNA ranging from 100 to 199 kbp in size (Xue and Cheng, 2011;Huang et al, 2012b).…”

“…Eighteen isolates or strains belonging to four ascovirus species have been reported in the world (Bigot et al, 2011;Huang et al, 2012a), in which five ascovirus isolates genomes that are SfAV-1a, TnAV-6a (Trichoplusia ni ascovirus 6a, previously named at its discovery TnAV-2c (Wang et al, 2006)), HvAV-3e, HvAV-3g, and DpAV-4a have been sequenced (Wang et al, 2006;Bideshi et al, 2006;Asgari et al, 2007;Bigot et al, 2009;Huang et al, 2012b). All these reported genomes have a double-stranded circular DNA ranging from 100 to 199 kbp in size (Xue and Cheng, 2011;Huang et al, 2012b). Based on the biological characteristics analysis, the species HvAV-3a is the most diverse and widely distributed from America to Asia and Australia (Hamm et al, 1998;Huang et al, 2012a), in which two isolates HvAV-3e and HvAV-3g genomic sequences were reported from Australia and Indonesia, respectively (Asgari et al, 2007;Huang et al, 2012b), but no HvAV-3a isolate from America is sequenced.…”

“…All these reported genomes have a double-stranded circular DNA ranging from 100 to 199 kbp in size (Xue and Cheng, 2011;Huang et al, 2012b). Based on the biological characteristics analysis, the species HvAV-3a is the most diverse and widely distributed from America to Asia and Australia (Hamm et al, 1998;Huang et al, 2012a), in which two isolates HvAV-3e and HvAV-3g genomic sequences were reported from Australia and Indonesia, respectively (Asgari et al, 2007;Huang et al, 2012b), but no HvAV-3a isolate from America is sequenced. To understand the diversity and, evolution and geographical differentiation of the HvAV-3a isolates, we report the complete genome of HvAV-3f which was a HvAV-3a isolate from USA, and make comparison for HvAV-3f with the other 5 previously published ascovirus genomes.…”