Analysis of the Complete Genome Sequence of the Hz-1 Virus Suggests that It Is Related to Members of the Baculoviridae

Abstract

We report the complete sequence of a large rod-shaped DNA virus, called the Hz-1 virus. This virus persistently infects the Heliothis zea cell lines. The Hz-1 virus has a double-stranded circular DNA genome of 228,089 bp encoding 154 open reading frames (ORFs) and also expresses a persistence-associated transcript 1, PAT1. The G؉C content of the Hz-1 virus genome is 41.8%, with a gene density of one gene per 1.47 kb. Sequence analysis revealed that a 9.6-kb region at 43.6 to 47.8 map units harbors five cellular genes encoding proteins with homology to dUTP pyrophosphatase, matrix metalloproteinase, deoxynucleoside kinase, glycine hydroxymethyltransferase, and ribonucleotide reductase large subunit. Other cellular homologs were also detected dispersed in the viral genome. Several baculovirus homologs were detected in the Hz-1 virus genome. These include PxOrf-70, PxOrf-29, AcOrf-81, AcOrf-96, AcOrf-22, VLF-1, RNA polymerase LEF-8 (orf50), and two structural proteins, p74 and p91. The Hz-1 virus p74 homolog shows high structural conservation with a double transmembrane domain at its C terminus. Phylogenetic analysis of the p74 revealed that the Hz-1 virus is evolutionarily distant from the baculoviruses. Another distinctive feature of the Hz-1 virus genome is a gene that is involved in insect development. However, the remainder of the ORFs (81%) encoded proteins that bear no homology to any known proteins. In conclusion, the sequence differences between the Hz-1 virus and the baculoviruses outnumber the similarities and suggest that the Hz-1 virus may form a new family of viruses distantly related to the Baculoviridae.

Giant Marseillevirus highlights the role of amoebae as a melting pot in emergence of chimeric microorganisms

“…So far, only two viruses, Heliothis zea virus 1 and Cotesia plutellae bracovirus, which do not belong to the NCLDV, have been shown to encode histone-like proteins (15,16). The histone-like proteins of Marseillevirus were detected in the viral particle (Table S1), suggesting that these proteins could condense DNA to facilitate viral DNA packaging.…”

Nudivirus Genomics and Phylogeny

“…It was also found within 200 bp of the initiation codon of HzNV-1 ORF81 based on in silica sequence analysis (Cheng et al 2002). Although consensus early and late promoter motif sequences similar to those of baculoviruses were predicted in nudivirus ORFs, convincing experimental data remain unavailable (Cheng et al 2002, Wang et al 2007c). …”

“…HzNV-1 was the first completely sequenced nudivirus (Cheng et al 2002). Its genome is 228,089 bp in size, has a G+C content of 42%, and encodes 154 ORFs (Table 1).…”

Identification of bracovirus particle proteins and analysis of their transcript levels at the stage of virion formation

“…These observations suggest that some of the BV-and nudivirus-particle proteins diverged to an extent that relatedness is no longer detectable. Interestingly, for 50-75 % of putative ORFs of nudiviruses and SGHV no homology to proteins in the databases was found (Cheng et al, 2002;Wang et al, 2007b, c;GarciaMaruniak et al, 2008;Abd-Alla et al, 2008).…”

“…Currently the nudiviruses comprise five viruses: Oryctes rhinoceros nudivirus (OrNV), Gryllus bimaculatus nudivirus (GbNV), Heliothis zea nudiviruses 1 and 2 (HzNV-1 and HzNV-2) and Penaeus monodon nudivirus (PmNV) (Wang & Jehle, 2009). The genomes of OrNV, GbNV and HzNV-1 have been fully sequenced (Wang et al, 2007b, c;Cheng et al, 2002). The genome of HzNV-2 has been sequenced and is reported to have 93.5 % nucleotide sequence identity with HzNV-1 (Wang et al, 2007a) but the sequence is not publicly available.…”