Submitted to: Journal of Invertebrate Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 1, 1997
Publication Date: N/A
Interpretive Summary: One of the important microbials used in the control of major crop pests such as the cotton bollworm, corn earworm, tomato fruitworm and tobacco budworm is a baculovirus that was isolated from the cotton bollworm. It is very important to know what insect cells and growth media are necessary for the optimum production of this baculovirus in the laboratory. This study shows that of three clonal lines from the cotton bollworm, one of them produced significantly higher concentrations of virus than the others. It was also demonstrated that the best growth medium was one that was supplemented with fetal bovine serum. A modified quantitative method was developed to measure the concentration of baculovirus produced. The information obtained in this study will be helpful in optimizing the production and quantitation of this baculovirus in the laboratory for use as a biological control agent.
Technical Abstract: Helicoverpa zea clonal cell lines AM1-A7, AM1-A11, and AM1-B3 derived from the parental cell line BCIRL-Hz-AM1 were compared in serum-free and in serum containing growth media for their ability to produce the Helicoverpa zea nuclear polyhedrosis virus (HzSNPV) as well as for their plaque-forming capability. Extracellular virus (ECV) from HzSNPV can be quantitated by the end-point dilution method (TCID50) and the plaque assay method (PAM) utilizing monolayers of cells. In the present investigation a modified PAM was employed using an agarose overlay with a lower gelling temperature than is commonly used in the PAM for insect cell lines. The results of the present study show that the highest titer of 5.5 x 10**6 PFU/ml was produced by AM1-B3 in TC199-MK assayed on AM1-A11 in Excell**TM400. Furthermore the AM1-A 11 clonal line in serum -free medium proved to be the best plaque-forming cell line for quantitating ECV. In general the clonal lines in the serum containing medium TC199-MK produced equivalent or highe titers than in the serum-free medium Excell**TM400. The results of this study will be helpful in selecting the best clonal cell line for HzSNPV production and for quantitating ECV by PAM.