ARS | Publication request: DIETARY SELENIUM SUPPLEMENTATION BOOSTS PLASMA PHENOLOXIDASE ACTIVITY AND ANTIVIRAL IMMUNOCOMPETENCE

Submitted to: University of Missouri Life Sciences Week
Publication Type: Abstract Only
Publication Acceptance Date: February 25, 2004
Publication Date: April 18, 2004
Citation: Shelby, K., Popham, H.J. 2004. Dietary selenium supplementation boosts plasma phenoloxidase activity and antiviral immunocompetence [abstract]. University of Missouri Life Sciences Week. Available: http://lifesciencesweek.missouri.edu/uploads/abstract_pdf/shelbyk@1.pdf.

Technical Abstract: Herbivorous insects encounter a range of dietary nutrients, antioxidants, co-factors and plant secondary metabolites which may modulate their resistance to microbial infections. A colony of the lepidopteran pest insect Trichoplusia ni has been maintained at BCIRL for generations on an artificial diet with no added Selenium. These depleted, or low-Se, insects grow and reproduce normally. However, we have found that supplementation of the diet of these Se-depleted larvae with 10 ppm or less Sodium Selenite elevated resistance to per os infection with the baculovirus Autographa californica multiple nucleopolyhedrovirus (AcMNPV). T. ni larvae had a 5-10 fold higher LC50's when fed 5 or 10 ppm Se, respectively. Further, phenoloxidase (L-DOPA oxygen oxidoreductase, E.C. 1.14.18.1) activity in plasma drawn from 5-10 ppm Se supplemented fifth instar larvae visibly increased. This study lends support to the hypothesis that dietary Se may increase the immunocompetence of larval lepidopterans by elevating the expression or activity of plasma phenoloxidase, which in turn acts as an antiviral enzymatic activity direction upon AcMNPV budded virus within the hemocoel of infected insects.