Chemical Ecology The Chemistry of Biotic Interaction (1995) / Chapter Skim
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Polydnavirus-Facilitated Endoparasite Protection Against Host Immune Defenses
Polydnavirus-Facilitated Endoparasite Protection Against Host Immune Defenses
Pages 67-86
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From page 67... ...
The Chemistry of Eavesdropping, Alarm, and Deceit / 65 47. Stowe, M
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From page 69... ...
After replication and assembly in the nucleus of the calyx cells, the polydnavirus is "secreted" into the wasp oviduct where it accumulates along with the wasp egg and a complex of oviduct secretions. Upon oviposition, the virus is transferred to a permissive host in which the endoparasite egg will develop.
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From page 70... ...
sonorensis polydnavirus induces developmental arrest in H virescens larva (18, 24,
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From page 71... ...
sonorensis polydnavirus are encapsulated and killed. Preincubation with monoclonal antibodies specific for viral envelope proteins neutralized the effects of the virus on H
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From page 72... ...
sonorensis polydnavirus genes mapped and studied to date belong to gene families.
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From page 73... ...
sonorensis polydnavirus genes that are expressed in H virescens are grouped into two gene families: "repeat,' (25)
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Region A encompasses the 5' untranslated leader and the first 16 amino acids of the predicted open reading frame. Region B encompasses a stretch of 27 amino acids immediately preceding the cysteine motif and the primary sequence delineated by the first three cysteine residues of this motif.
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From page 75... ...
OPEN READING FRAMES OF 1:HE CYSTEINE-RICH GENES The cysteine motifs in this polydnavirus gene family are structurally analogous to the cysteine motifs of the cl) -conotoxins.
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From page 76... ...
The hypervariability in amino acids of the cysteine motif of these genes suggests that these proteins may bind to related, yet different, targets. The sequences encoding the cysteine motifs in WHv1.0 and WHv1.6 are 76% identical, counting a 33-bp deletion as a single mutational event; however, the two motifs are 58% identical at the amino acid level (451.
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From page 77... ...
sonorensis polydnavirus envelope proteins and soluble wasp oviduct and venom gland proteins. The viral envelope proteins had different molecular weights compared to
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From page 78... ...
The immunological relatedness of different viral envelope proteins to each other and to wasp venom proteins defines the venom-related gene family. The viral genes encoding the envelope proteins and the genes for the venom secretions are yet to be isolated and studied.
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From page 79... ...
Putative signal peptides at the N terminus of the open reading frames are not predicted for any of the 540-bp repeat gene protein sequences. These repeated elements share no significant homology to the cysteinerich gene family.
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From page 80... ...
sonorensis, experimental data demonstrate that polydnavirus gene expression in the parasitized insect is sufficient for parasite survival. Assuming that the polydnavirus genetic system is in a dynamic state of evolution, one must be curious about the molecular mechanisms by which the surviving wasps are able to retain the essence of the most effective polydnavirus genetics to favor the wasp's survival strategy.
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From page 81... ...
It is recognized that gene families are a major source of genetic variability and that families evolve by gene duplication followed by sequence divergence (104~. Gene duplication may occur during inter- and intramolecular recombination among the several viral genomic segments during viral DNA replication and/or by chromosomal crossing-over during wasp sexual reproduction.
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From page 82... ...
We have applied these models to assess if overdominant selection underlies the hypervariability of the intercysteine amino acid residues of the cysteine motif of the C sonorensis polydnavirus cysteine-rich gene family (451.
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From page 83... ...
The possible involvement of the cysteine-rich gene proteins in targeting parasitized host systems to facilitate parasite survival is currently a testable model for the role of polydnavirus proteins in inducing host immunosuppression and developmental arrest. If successful, our knowledge of these functions may provide additional insights for the biochemistry and cell biology of insect cellular immune processes.
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From page 84... ...
In the host, polydnavirus expression is detected by 2 hr and during endoparasite development. Most of the abundantly expressed viral genes expressed very early after parasitization belong to multigene families.
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From page 85... ...
Endoparasite Protection Against Host Immune Defenses /83 11. Tanaka, T
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From page 86... ...
(1990) Nucleic Acids Res.
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