The activity of phenoloxidase in haemolymph plasma is not a predictor of Lymantria dispar resistance to its baculovirus
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PLOS ONE. 12(8): e0183940. 16 p.
Host innate immunity is one of the factors that determines the resistance of insects to their entomopathogens. In the research reported here we studied whether or not phenoloxidase (PO), a key enzyme in the melanogenesis component of humoral immunity of insects, plays a role in the protection of Lymantria dispar larvae from infection by L. dispar multiple nucleopolyhedrovirus. We studied two types of viral infection: overt and covert. The following lines of investigation were tested: i) the intravital individual estimation of baseline PO activity in haemolymph plasma followed by virus challenging; ii) the specific inhibition of PO activity in vivo by peroral treatment of infected larvae with phenylthiourea (PTU), a competitive inhibitor of PO; iii) the evaluation of PO activity in the haemolymph plasma after larval starvation. Starvation is a stress that activates the covert infection to an overt form. All of these experiments did not show a relationship between PO activity in haemolymph plasma of L. dispar larvae and larval susceptibility to baculovirus. Moreover, starvation-induced activation of covert viral infection to an overt form occurred in 70 percent of virus-carrying larvae against the background of a dramatic increase of PO activity in haemolymph plasma in the insects studied. Our conclusion is that in L. dispar larvae PO activity is not a predictor of host resistance to baculovirus.
Kasianov, Nikita S.; Belousova, Irina A.; Pavlushin, Sergey V.; Dubovskiy, Ivan M.; Podgwaite, John D.; Martemyanov, Vyacheslav V.; Bakhvalov, Stanislav A.; Ling, Erjun. 2017. The activity of phenoloxidase in haemolymph plasma is not a predictor of Lymantria dispar resistance to its baculovirus. PLOS ONE. 12(8): e0183940. 16 p. https://doi.org/10.137/journal.pone.0183940.