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Insect virus: assays for toxic effects and transformation potential in mammalian cells
P C Hartig1, M A Chapman, G G Hatch
1Northrop Environmental Sciences, Research Triangle Park, North Carolina 27709.
Abstract:
The nuclear polyhedrosis virus of Autographa californica (AcNPV) was evaluated by using in vitro test systems for toxicity and transforming potential in mammalian cells. Mass cell cultures of CV-1 and WI38 cells appeared unaffected by AcNPV at a multiplicity of infection of 5. Human foreskin cells grew more slowly after inoculation but eventually produced healthy monolayers. The sensitivities of the inhibition of reproductive survivability assays were greater and demonstrated slight AcNPV toxicity to CV-1, WI38, and human foreskin cells. Toxicity was not ameliorated when gradient-purified or psoralen-inactivated virus was used, suggesting that the toxic component of the preparation is part of the virion or copurifies with it. AcNPV was not toxic to and did not transform BALB/c 3T3 cells or primary cell cultures derived from Syrian hamster embryo cells (SHE). Unlike the BALB/c 3T3 transformation assay, the SHE assay detected no spontaneous transformants. The SHE transformation assay can employ simian adenovirus 7 as a positive control. SHE are transformed by numerous viruses and so are useful in assessment protocols. This study suggests that in vitro assessment of viral pesticide toxicity should employ the inhibition of reproductive survivability assay and that transformation assessment is best done with the SHE-simian adenovirus 7 procedure.
Insights
Autographa californica (AcNPV) showed slight toxicity to mammalian cells using reproductive survivability assays but did not transform cells. This suggests specific in vitro assays for viral pesticide safety assessments.
Area of Science:
- Virology
- Cell Biology
- Toxicology
Background:
- Nuclear polyhedrosis viruses (NPVs) are used as biological pesticides.
- Assessing the in vitro toxicity and transforming potential of viral pesticides in mammalian cells is crucial for safety evaluations.
Purpose of the Study:
- To evaluate the in vitro toxicity and transforming potential of Autographa californica (AcNPV) in mammalian cell systems.
- To determine the most sensitive and reliable in vitro assays for assessing viral pesticide safety.
Main Methods:
- In vitro toxicity assays using CV-1, WI38, and human foreskin cells.
- Inhibition of reproductive survivability assays.
- Transformation assays using BALB/c 3T3 and Syrian hamster embryo (SHE) cells.
- Use of simian adenovirus 7 as a positive control for SHE transformation.
Main Results:
- AcNPV showed slight toxicity to CV-1, WI38, and human foreskin cells via inhibition of reproductive survivability assays.
- Toxicity was observed even with purified or inactivated AcNPV, indicating the toxic component is virion-associated.
- AcNPV did not induce toxicity or transformation in BALB/c 3T3 or SHE cells.
- The SHE assay detected no spontaneous transformants, but was effective with a positive control.
Conclusions:
- The inhibition of reproductive survivability assay is recommended for in vitro assessment of viral pesticide toxicity.
- The SHE cell transformation assay, with simian adenovirus 7 as a control, is suitable for evaluating the transforming potential of viral agents.