Biochemical comparison of virion proteins from five nuclear polyhedrosis viruses infecting plusiine larvae (Lepidoptera: Noctuidae)

High resolution two-dimensional gel electrophoresis of structural proteins of baculoviruses of Autographa californica and Porthetria (lymantria) dispar

The structural polypeptides of baculoviruses of Autographa californica (AcMNPV) and Porthetria dispar (PdMNPV) were analyzed by two-dimensional (2-D) gel electrophoresis. Purified proteins were solubilized in urea-NP40 mix and separated by isoelectric focusing in the first dimension; electrophoresis in the presence of sodium dodecyl sulfate (SDS) separated proteins by molecular weight in the second dimension. Eighty-one acidic polypeptides ranging in molecular weight from 13,500 to 86,000 Da were resolved in AcMNPV enveloped virions. The predominant polypeptide had a molecular weight of 41,500 and was considered to be the major capsid protein. Nucleocapsids from AcMNPV were resolved into 64 polypeptides. At least 11 of the polypeptides, including most of the high molecular weight proteins, that were not resolved in nucleocapsids were considered to be envelope proteins. For PdMNPV enveloped virions, there were 95 acidic polypeptides ranging in molecular weight from 13,500 to 85,500. The predominant polypeptide had a molecular weight of 46,500 Da. Polyhedral proteins (polyhedrin) isolated from protease-inactivated polyhedra and separable into a single major polypeptide (approx. 31,000) on one-dimensional SDS-polyacrylamide gel electrophoresis were resolved into six polypeptides for both viruses. All six polyhedrin polypeptides had the same molecular weight, but their isoelectric points ranged from pH 5.3 to 5.9 for AcMNPV and from pH 5.7 to 6.2 for PdMNPV. These six polypeptides were also detected when protease-inactivated or noninactivated whole polyhedra were analyzed directly by 2-D electrophoresis. It is assumed that not all the observed baculovirus polypeptides were unique species. Some proteins, especially the polyhedrin polypeptides, appeared to be related and had altered mobilities as a consequence of post-translational modifications.

Physical maps of SfMNPV baculovirus DNA and its genomic variants

Spodoptera frugiperda MNPV was plaque-purified, and the viral DNA from the plaque-purified isolates was analyzed with restriction endonuclease enzymes. Seven distinct variants were identified when the DNA of the isolates were analyzed by EcoRI and HindIII. The DNAs of the SfMNPV predominant type (prototype) and the variants were mapped with BamHI, BglII, BstEII, EcoRI, HindIII, KpnI, and PstI by multiple enzyme digestion and blot hybridization. The cleavage sites generated by the seven restriction enzymes were ordered, and the sites were assigned map coordinates using a least-squares procedure. Since Autographa californica MNPV-E2 EcoRI fragment I, which contains the polyhedrin gene, hybridized with SfMNPV EcoRI fragment P, the physical map of SfMNPV was oriented with EcoRI P on the left, with site 1 being the EcoRI site between fragments F and P. The calculated genome size was 121.76 kilobase pairs or 80.36 X 10(6) Da. The DNA from each variant was compared to the DNA of the prototype for insertions, deletions, and new restriction sites. Physical maps were generated for each of the variants. The differences between the variant and the prototype were confined to four regions in the SfMNPV genome representing less than 16% of the prototype genome.

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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Structural Polypeptides of the Granulosis Virus of Plodia interpunctella

Techniques were developed for the isolation and purification of three structural components of Plodia interpunctella granulosis virus: granulin, enveloped nucleocapsids, and nucleocapsids. The polypeptide composition and distribution of protein in each viral component were determined by sodium dodecyl sulfate discontinuous and gradient polyacrylamide slab gel electrophoresis. Enveloped nucleocapsids consisted of 15 structural proteins ranging in molecular weight from 12,600 to 97,300. Five of these proteins, having approximate molecular weights of 17,800, 39,700, 42,400, 48,200, and 97,300, were identified as envelope proteins by surface radioiodination of the enveloped nucleocapsids. Present in purified nucleocapsids were eight polypeptides. The predominant proteins in this structural component had molecular weights of 12,500 and 31,000. Whereas no evidence of polypeptide glycosylation was obtained, six of the viral proteins were observed to be phosphorylated.