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Characterization of nuclear polyhedrosis virus DNAs
Journal of Virology
|December 1, 1973
Summary
Nuclear polyhedrosis virus (NPV) DNAs from Trichoplusia ni (SNPV) and Spodoptera frugiperda (MNPV) show similar properties and sizes to granulosis viruses. These NPV DNAs exist as a mix of covalently closed, relaxed circular, and linear forms.
Area of Science:
- Molecular Virology
- Insect Pathology
- Biochemistry
Background:
- Nuclear polyhedrosis viruses (NPVs) are significant pathogens of insects, impacting both natural populations and agricultural pest control.
- Understanding the genomic properties of NPVs is crucial for developing effective biocontrol strategies and for fundamental virological research.
- Previous studies have characterized various insect viruses, but a detailed comparison of NPV DNA properties, including their circularity and size relative to other viruses, is warranted.
Purpose of the Study:
- To characterize and compare the DNA from singly-enveloped nucleocapsids (SNPV) of Trichoplusia ni and multiple embedded nucleocapsids (MNPV) of Spodoptera frugiperda and Rachiplusia ou.
- To determine the molecular weight and structural forms (covalently closed, relaxed circular, linear) of NPV DNAs.
- To compare the size of NPV DNAs with granulosis virus DNAs and T4 bacteriophage DNA, and to analyze base composition relative to host insect DNA.
Main Methods:
- Neutral sucrose sedimentation was employed to estimate the molecular weights of the viral DNAs.
- Hydrodynamic properties of the viral DNAs were analyzed.
- DNA was isolated from purified virus or directly from occluded virus for structural analysis.
Main Results:
- NPV DNAs from T. ni (SNPV) and S. frugiperda/R. ou (MNPV) exhibited similar hydrodynamic properties and molecular weights.
- NPV DNAs were found to be composed of approximately 20-30% double-stranded covalently closed molecules, 60% relaxed circles, and less than 10% linear duplex DNA.
- The molecular weights of NPV DNAs (90-100 x 10^6) were slightly smaller than T4 bacteriophage DNA (108 x 10^6) and granulosis virus DNAs.
Conclusions:
- NPV DNAs share significant similarities in size and structure, irrespective of whether they form single nucleocapsids or bundles.
- The DNA composition and size are comparable to those of granulosis viruses, suggesting conserved genomic features within insect baculoviruses.
- Further investigation into the base composition of NPVs in relation to their insect hosts could reveal insights into host-virus interactions.