Morphological variations in the cytopathology associated with granulosis virus in the fruit-tree leaf roller, Archips argyrospila

The complete sequence of the Adoxophyes orana granulovirus genome

The nucleotide sequence of the Adoxophyes orana granulovirus (AdorGV) DNA genome was determined and analysed. The genome contains 99,657 bp and has an A + T content of 65.5%. The analysis predicted 119 ORFs of 150 nucleotides or larger that showed minimal overlap. Of these putative genes, 104 (87%) were homologous to genes identified previously in other baculoviruses. The mean overall amino acid identity of AdorGV ORFs was highest with CpGV ORFs at 48%. Sixty-three ORFs were conserved among all lepidopteran baculoviruses and are considered to be common baculoviral genes. Several genes reported to have major roles in baculovirus biology were not found in the AdorGV genome. These included chitinase and cathepsin, which are involved in the liquefaction of the host, which explains why AdorGV-infected insects do not degrade in a typical manner. The AdorGV genome encoded two inhibitor of apoptosis (iap) genes iap-3 and iap-5. Among all of the granuloviruses genomes there was a very high level of gene collinearity. The genes shared by AdorGV and CpGV had exactly the same order along the genome with the exception of one gene, iap-3. The AdorGV genome did not contain typical homologous region (hr) sequences. However, it contained nine repetitive regions in the genome.

Characterization of a granulosis virus from the castor semilooper, Achaea janata L

The granulosis virus isolated from Achaea janata is composed of capsules (463 +/- 25 x 280 +/- 22 nm) which contain single virus particles. The virus particles (274 +/- 9 x 95 +/- 4 nm) contain nucleocapsids (297 +/- 7 x 52 +/- 2 nm) within an envelope. The empty capsids measured 265 +/- 9 x 63 +/- 3 nm. SDS-PAGE electrophoresis was carried out and the granulin polypeptide (28.9 +/- 0.5 kDa) was found to contain two other associated polypeptides of molecular weight 58.2 +/- 2.3 and 55.2 +/- 1.3 kDa, respectively. Protein gel electrophoresis of granulin gave degradation products from 27.2 to 15.4 kDa, when protease associated with capsules was not inhibited. The virus particles were found to contain 16 polypeptides with molecular weights ranging from 106.4 +/- 2.1 to 15. 5 +/- 0.8 kDa and 12 of these polypeptides were contained in the nucleocapsids. The major polypeptide of the capsids had molecular weight of 34.9 +/- 0.3 kDa. Restriction profiles of viral DNA with seven enzymes were obtained and the average molecular weight was found to be approximately 92 +/- 7 kb. Southern hybridization of the restriction profiles of the viral DNA with SalI fragment from pUCTnGV (containing granulin gene) was performed and hybridization was found on single discrete fragments with molecular weights ranging from 12.0 to 2.7 kb. The GC content of AjGV DNA was found to be 65 +/- 1% and the genome size as determined from reassociation kinetics was 92 kb.

Polyhedron-like inclusion body formation by a mutant nucleopolyhedrovirus expressing the granulin gene from a granulovirus

The polyhedrin gene in Bombyx mori nucleopolyhedrovirus (BmNPV) was replaced with the granulin gene of Trichoplusia ni granulovirus (TnGV). The substitution was verified by Southern hybridization, and expression of granulin by the mutant virus, BmGran, was demonstrated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and by amino acid sequencing of the predominant protein of BmGran inclusion bodies (IBs). Light and electron microscopy examination of BmGran-infected B. mori and BmN cells revealed large, cuboidal, polyhedron-like IBs in the nucleus and cytoplasm, but granules were not seen. IBs contained small, parallel, electron-dense streaks, which defined the geometric pattern of crystallization. Geometric patterns of nuclear IBs were frequently disrupted by occlusion of polyhedron envelope fragments, resulting in IB instability and fracturing. Virions were not embedded in most of the polyhedron-like IBs, but accumulated with polyhedron envelope fragments. Some virions were coated with matrix protein and were partially wrapped by polyhedron envelope. These results suggested that (1) the amino acid sequence of granulin insufficient for determining IB morphology in TnGV-infected cells, and TnGV may have genes, not present in BmNPV, that control granule formation, and (2) interactions among the virion, the IB envelope, and the matrix protein may be important in virion occlusion and IB morphology and stability.

Temporal events in the invasion of the codling moth, Cydia pomonella, by a granulosis virus: An electron microscope study

The replication cycle of the granulosis virus of Cydia pomonella, the codling moth, was studied at the cellular and tissue level. Membranelike complexes were observed forming within the remnants of the nucleolus in the cytoplasm of infected cells. Differences in cell polarity relative to the sites of virus entry assembly and budding as well as differences in the temporal aspects of replication were observed between midgut, fat body, and epidermal cells. The progressive spread of virus throughout larval tissues was studied at 24, 32, 48, 56, and 72 hr postinfection. The basal lamina seemed to be an effective barrier for the release of budded progeny virus into the hemocoel and large numbers of budded virus were produced.

Granulosis viruses, with emphasis on the GV of the Indian meal moth, Plodia interpunctella

The granulosis viruses and nuclear polyhedrosis viruses are being considered for use as biological insecticides for control of their insect hosts. Many of these insect species, which include some of the most serious pests of agriculture and forests, have become difficult to control because they have developed resistance to chemical insecticides. Several laboratory and field studies have demonstrated that the baculoviruses (GV and NPV) are promising alternatives to chemicals for the control of economically important insects. These viruses are highly virulent, selective, and stable, and the impact on the environment following their application is minimal. A decision concerning the application of baculoviruses to stored grain and field crops must be based upon a prudent consideration of the benefits to be obtained and the potential risks of their use. Such decisions should be made only after consideration of the physical, chemical, and biological properties of these viruses. In addition, methods must be developed for the unequivocal identification of these viruses, and their effects on nontarget species at the cellular and molecular levels must be investigated. This can best be accomplished if a sufficient body of knowledge regarding the molecular properties of these viruses and their infection process is accumulated by an extensive quantitative approach. Much of this knowledge is lacking because, prior to their consideration for use as insecticides, the baculoviruses appeared to have little medical or economic importance. As a result, interest in studying them was limited. It has become obvious that the molecular properties of these viruses must be investigated if full advantage is to be taken of using them as insect control agents, and if present and future problems concerning their use as insecticides are to be handled properly. Fundamental research on the biochemical and biophysical properties of baculoviruses has concentrated mainly on a variety of nuclear polyhedrosis viruses (Harrap, 1972a,b; Harrap et al., 1977; Summers and Smith, 1975a,b; Arif and Brown, 1975). Much of this progress can be attributed to tissue culture-host cell systems available for the NPVs. The in vitro host system(s) has allowed insect virologists to make phenomenal strides in understanding the cellular and molecular events of virus infection, and, in addition, to enter the era of biochemical sophistication in which animal virology is found at present.(ABSTRACT TRUNCATED AT 400 WORDS)

Applied and molecular aspects of insect granulosis viruses

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