|Ignoffo, Carlo - ARS RETIRED|
Submitted to: In Vitro Cellular And Developmental Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 14, 2002
Publication Date: March 1, 2002
Citation: GRASELA, J.J., MCINTOSH, A.H., IGNOFFO, C.M., GOODMAN, C.L. HOST INSECT CELLS AND THEIR POTENTIAL AS STABILIZATION BARRIERS FOR DNA ANDMNPV AND SNPV AGAINST UV-B SIMULATED SUNLIGHT INACTIVATION. IN VITRO CELLULAR AND DEVELOPMENTAL BIOLOGY. 2002. V. 38. P. 173-177. Interpretive Summary: One of the major barriers to the further development of baculoviruses as effective insect control agents is inactivation of the virus in the field. The objective of this study was to determine the potential of insect cells once infected with a baculovirus to protect the virus from exposure to damaging UV-B irradiation. Of the two insects that were infected with virus, the cabbage looper cells were the least sensitive to UV light exposure and produced a higher amount of virus than similarly exposed corn earworm cells. Two genes that are known to be involved in the repair of DNA damage by UV light in non-insect organisms also were detected in the two insects cells in this study. This information will contribute to a further understanding of the interaction between the virus and its insect host and has important implications for the possible development of UV resistant baculoviruses for insect control.
Technical Abstract: A cell line from Trichoplusia ni (TN-CL1) infected with the Autographa californica MNPV and a cell line from Helicoverpa zea (BCIRL-HZ-AM1) infected with a Helicoverpa zea SNPV clone were subjected to UV-B irradiation at a predetermined level of exposure that would inactivate greater than 95% of the virus inoculum. The working hypothesis was that the homologous insect cells would utilize their inherent DNA repair mechanism(s) to prevent, repair or at least mitigate the damaging effects of UV-B light on viral DNA synthesis. We attempted to determine this indirectly by using infected cells that were subjected to UV-B irradiation at different postinoculation periods under two experimental treatments. Of the two cell lines infected with their respective viruses, TN-CL1 cells were the least sensitive to UV-B light as its production of ECV and OB was higher than virus from infected BCIRL-HZ-AM1 cells across all the tested postinoculation periods. ECV and OB production from both cell lines was lower in the exposed (non-shielded) treatment than in the shielded (exposed) treatment. However, AcMNPV was produced in enough quantity to indicate that TN-CL1 might impart a level of protection to the virus against UV light. This differential response of the two cell lines to UV-B irradiation when in an uninfected state appears to reflect the potential of how well the two cell lines can respond to UV exposure in terms of the production of their viral ECV and OB. PCR was performed on the above mentioned cell lines as well as a Dipteran and two other Lepidopteran cell lines using degenerate primers designed to detect amplified fragments from the RAD54 and phr genes. RAD54 was detected in TN-CL1, BCIRL-HZ-AM1 and three other cell lines, whereas phr was detected in only the TNCL1 cells.