Sequence and organization of the Trichoplusia ni ascovirus 2c (Ascoviridae) genome

The complete Trichoplusia ni ascovirus 2c (TnAV-2c) genome sequence was determined. The circular genome contains 174,059 bp with 165 open reading frames (ORFs) of greater than 180 bp and two major homologous regions (hrs). The genome is quite A + T rich at 64.6%. Fifty-four ORFs had homologues in other insect viruses, such as ascoviruses, iridoviruses, baculoviruses and entomopoxviruses; 30 ORFs showed low identities with those from different parasitic protozoa and 12 ORFs were unique to TnAV-2c. TnAV-2c has 15 ORFs that could be grouped into six gene families. Three major conserved repeating sequences were identified and were interspersed in two regions. BLAST analyses revealed that there were 16 enzymes involved in gene transcription, DNA replication, and nucleotide metabolism. TnAV-2c has 12 and 25 ORFs sharing high identities with ascovirus and iridovirus homologues, respectively. The codon usage bias appears to be more similar to Spodoptera frugiperda ascovirus 1a than to iridoviruses.