Helicoverpa zea nudivirus 2 (HzNV-2, Hz-2V, gonad specific virus [GSV], or Heliothis zea nudivirus 2) is an enveloped, rod-shaped, nonoccluded, double stranded DNA (dsDNA) sexually transmitted virus whose natural host is the corn earworm moth.
It was originally identified in a colony of corn earworm moths established and maintained in Stoneville, Mississippi, U.S. and was found to be responsible for the sterility of those infected.
[2] It is highly unlikely that the common effects of HzNV-2 on their hosts, malformed reproductive tissues causing infertility, would have been selected for establishing an ovarian cell line.
Infected moths are referred to as either asymptomatic (AS) or agonadal (AG), due to the virus causing larvae to never form functional gonads.
After mating, the virus productively replicates inside the females, which makes the viral dose increase on successive oviposition days.
[6][8] Female hosts infected through vertical transmission often do not develop several reproductive structures, including their ovaries, bursa copulatrix, accessory glands, and spermatheca.
[1] Viral replication in female gonads result in hypertrophy of the oviducts and proliferation of the cells making up these tissues.
[11] Infected males may grow to have small, unfused testes, no seminal vesicles, vas deferencia, or accessory glands.
[6][8] Accessory glands produce pheromonostatic peptide (PSP), which inhibits the amount of mating pheromones females make.
[12] The tissues needed for the initiation of copulation and the transfer of reproductive fluids during mating function normally.
[2] The lumen of the primary simplex of infected male moths is greatly filled with virus particles that they very likely transmit to healthy females without fertilizing them.
[8] The genome of HzNV-2 is a circular double-stranded DNA molecule of 231,621 bp, making it the largest dsDNA insect virus.
Of the 38 genes with homologues, 6 are involved in DNA replication, 4 in transcription, 5 in nucleic acid metabolism, 3 structural proteins.
[1] The C-terminal region of Hz2V008 has homology with the catalytic domain for integrase and recombinase, which has DNA breaking and rejoining activity.
The best similarity to this gene comes from monodon baculovirus and Gryllus bimaculatus nudivirus (GbNV), suggesting a possible common ancestor.
[1] The C-terminal region of Hz2V038 is similar to a poxvirus D5 protein and it has homology DNA helicase, essential for virus replication.
[1][22] Hz2V051 is most similar to GbNV lef-8, which helps encode one of the main catalytic subunits of the baculovirus RNA polymerase.
[24][25] Hz2V026 is most similar to GbNV pif-2 and Autographa californica multiple nucleopolyhedrovirus (AcMPV), and it may form disulfide bonds and be a structural component of the occlusion-derived virus envelope.
[1][27][28] Hz2V106 shows homology with baculovirus p74 and likely mediates the specific binding of the virus particle to host cells by aiding the formation of disulfide bonds inside its C-terminal transmembrane's membrane anchoring domain.
[1][29][30] Hz2V035 is most similar to Bombyx mori thymidlylate synthase and is likely involved in the synthesis of dTMP precursors from dUTP.
[40] Hz2V007 is very similar to the Bombyx mori carboxylesterase (COE) and, to a lesser degree, Anopheles gambiae juvenile hormone esterase (JHE).
[1] Hz2V023 shows homology to the major facilitator superfamily (MFS), specifically Aedes aegypti adenylate cyclase.
They code for carrier proteins involved in uptaking and effluxing small molecules, particularly sugar and drugs respectively.
[1] GMPK transfers the terminal phosphate group of ATP and GMP in order to make ADP and GDP, a critical step in the biosynthesis of GTP.
[43] MMPs are important in cellular differentiation, morphogenesis, and pericellular proteolysis of the extracellular matrix and other cell surface molecules.
[1] Its function is unknown, but ac81 is considered a baculovirus core gene[45] Hz2V099 is similar to a prokaryotic acetylesterase (Aes),[1] a member of the esterase/lipase family that plays a role in the control of a transcriptional activator.