Submitted to: Molecular Insect Science International Symposium Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 4/7/2006
Publication Date: 5/20/2006
Citation: Popham, H.J. 2006. Antiviral response in Heliothis virescens [abstract]. Molecular Insect Science International Symposium Proceedings. p. 70.
Technical Abstract: Lepidopteran larvae are known to resist baculovirus infection by the selective apoptosis of infected midgut epithelial cells, and by the sloughing off of infected cells from the midgut. Once the infection breaches the midgut epithelial barrier and propagates from infective foci to the hemocoel however, there are few known mechanisms to account for the resistance and clearance of infection observed in some virus/host combinations. Utilizing an in vitro assay, Heliothis virescens larval plasma was found to contain high levels of an antiviral activity against Helicoverpa zea single nucleopolyhedrovirus (HzSNPV) budded virus. The innate factor responsible for the virucidal effect was identified as phenoloxidase. To elucidate the contributions of phenoloxidase to the innate immune response against baculovirus infection, specific inhibitors were employed. In vitro the general inhibitors of melanization (N-acetyl cysteine, ascorbate and glutathione), and specific inhibitors of phenoloxidase (phenylthiourea, and Kojic acid), completely blocked virucidal activity up to the level seen in controls. Addition of the enzyme catalase to plasma did not affect virucidal activity; however addition of superoxide dismutase exhibited a modest inhibitory effect. Inhibitors of nitric oxide synthase activity did not affect virucidal activity. Beyond innate virucidal activity, proteins induced by viral infection were also studied. Using two dimensional difference gel electrophoresis (DIGE, Amersham), protein expression was compared between plasma from uninfected and infected larvae. Preliminary results of this study will be presented.