Using Sindbis Virus Expression System to Study the Roles of Prophenoloxidase in the Melanization of Mosquito Armigeres subalbatus

• Main Authors: Hsi-Ming Tseng, 曾錫明
• Other Authors: Cheng-Chen Chen
• Format: Others
• Language: zh-TW
• Published: 2000
• Online Access: http://ndltd.ncl.edu.tw/handle/05846579450813799592

碩士 === 國立陽明大學 === 寄生蟲學研究所 === 88 === ABSTRACT By using double subgenomic Sindbis (dsSIN) virus expression system, we previously demonstrated that the melanization of microfilariae (mf) in mosquito Armigeres subalbatus could be almost abolished by transducing the mosquitos with a 600-base antisense sequence targeted to the highly conserved copper-binging region of prophenoloxidase I (pro-PO I), one of the key enzyme in the biosynthesis of melanotic material in insects. In this study, the temporal effects of the inhibition of melanizaton of mf in the transduced mosquitoes was further elucidated. It was found that the degree of melanization of mf was progressively decreased as the time of postinfection of dsSIN viruses was increased in mosquitoes. At 15 days postinfection, 96% of mf recovered from mosquitoes were devoided of deposition of melanotic material on their surface and only a few mf were slightly melanized. Western blot analysis demonstrated that the amount of an anti-prophenoloxidase antibody-crossreative polypeptide (78 KD) was significantly reduced in the hemolymph of mosquitoes transduced with a 600-base antisense sequence of pro-PO. In addition, we found that the melanization of mf in mosquitoes could also be inhibited by transducing mosquitoes with a smaller antisense sequence (147 base) targeted to the highly conserved region of copper binding Site A (CuA) of As-proPOI. However, the egg tanning in mosquitoes transduced with As-proPOIa dsSIN viruses was not significantly affected. These results suggested that As-proPOI is responsible for the melanization of parasites but not egg tanning in Armigeres subalbatus.