Lepidopteran larvae are known to resist baculovirus infection by selective apoptosis or sloughing off of infected cells from the midgut. Once the baculovirus infection breaches the midgut barrier, however, there are few known mechanisms to account for the resistance and clearance of infection observed in some virus/host combinations. We tested the hypothesis that factors in the plasma of the insect could act to limit the spread of baculoviruses within the hemocoel. We have developed an in vitro assay in which Helicoverpa zea single nucleopolyhedrovirus (HzSNPV) particles were pre-incubated with plasma collected from uninfected Heliothis virescens larvae prior to in vitro assay on HzAM-1 cells. The pre-incubation of virus reduced the TCID50/ml by more than 40 fold (7.7± 3.3 x 105 to 1.8±1.3 x 104). The virucidal activity was stable to freezing, but inactivated by incubation at 55°C and by incubation with proteinase K. We will report on the biological and biochemical characterization of this constitutive humoral antiviral mechanism in insects.
Species 1: Lepidoptera Noctuidae Heliothis virescens (tobacco budworm)
Keywords: HzSNPV, immunity
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