Author
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LYNN, DWIGHT |
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Submitted to: Journal of Invertebrate Pathology
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 5/5/2003 Publication Date: 7/1/2003 Citation: Lynn, D.E. 2003. Comparative susceptibilities of insect cell lines to infection by teh occlusion-body derived phenotype of baculoviruses. Journal of Invertebrate Pathology. Interpretive Summary: Insect viruses hold great promise for use as safe biopesticides for control of agricultural pests. However, a wide diversity of viruses exists with potential against particular pest insects. In the current study, the infectivity of three strains of a virus was assayed on a dozen insect cell lines to determine their relative pathogenicity. The resulting data, which showed that two strains had a greater pathogenicity overall while the third had a higher pathogenicity for cells from certain insect species, can be used by companies interested in developing these agents as biopesticides for help in determining the appropriate virus strain for specific applications. Additional results in this study showed that infectivity was increased on certain cell lines when the virus was treated with a digestive enzyme, trypsin. This information will be of interest to other scientists that are attempting to understand the infection process of these viruses. Technical Abstract: Twelve insect cell lines from six species were tested for susceptibility to baculovirus infection by the occlusion-derived virus (ODV) phenotype by use of a typical endpoint assay procedure. ODV from three nucleopolyhedroviruses (NPVs)(Autographa californica NPV, Anagrapha falcifera NPV, and Anticarsia gemmatalis NPV) were prepared by alkali treatment (sodium carbonate) of occlusion bodies (OBs). The resulting virus titers reveal the relative susceptibility of each cell line to the three viruses. More than a four-log difference was realized for each of theses viruses between the various cell lines. The TN368 line from Trichoplusia ni was only marginally susceptible to ODV from each virus, showing only 3 to 6 infectious units (IU) per million OBs while the gypsy moth line, LdEp, was most susceptible, realizing more than 100,000 IU/million OBs. The other lines tested showed various levels of susceptibility between these two extremes and also varied between the three viruses tested. In additional tests, the ODV were treated with trypsin prior to application to the cells. With most cell lines, this treatment increased the infectivity of each virus by 2 to 10-fold. Exceptions to this trend included the gypsy moth LdEp line, on which the trypsinized AcMNPV and AfMNPV ODV were less infectious than the same virus without trypsin, and the TN-368 line, on which the trypsinized AcMNPV ODV was 5000-times more infectious and the trypsinized AfMNPV ODV was 75,000-times more infectious. The variable results of trypsinized virus on the different lines are probably due to the levels of endogenous protease activity in the various lines, but the mode of action of the trypsin has not been elucidated. |
