An Anticarsia gemmatalis multiple nucleopolyhedrovirus mutant, vApAg, induces hemocytes apoptosis in vivo and displays reduced infectivity in larvae of Anticarsia gemmatalis (Hübner) (Lepidoptera: Noctuidae)

摘要

An Anticarsia gemmatalis multiple nucleopolyhedrovirus (AgMNPV) mutant, vApAg, inducesapoptosis in a cell culture derived from Anticarsia gemmatalis (UFL-AG-286), reducing viralprogeny. We have investigated apoptosis induction in vivo by vApAg in A. gemmatalis larvaeand its correlation to infectivity reduction. LC50, LD50, LT50 and the mean time to death oflarvae were determined for vApAg and AgMNPV. Apoptosis was accessed for hemocytes ofinfected larvae using light and transmission electron microscopy. All types of hemocytes can beinfected by vApAg. After 12 h post-infection (h p.i.), typical cellular modifications associated tonucleopolyhedrovirus infection were observed. Apoptosis becomes evident after 24 h p.i., andmassive after 72 h p.i. Necrosis of infected cells was also observed. Despite cell death,hemocytes produced budded viruses and polyhedra. Pl and gh1-type hemocytes presentedphagocytic activity. Agarose gel electrophoresis revealed fragmentation of hemocytes DNA atlate times post-infection. The LC50 and LD50 were between five- and six-fold higher for vApAg.The LT50 and the mean time to death were higher for vApAg in a same treatment or for asimilar mortality induced by AgMNPV. These results show correlation of apoptosis and thereduced infectivity of vApAg in A. gemmatalis larvae.