Do ancient viral genes derived from endogenous viral elements induce significant fitness costs in mosquitoes?

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K19119
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 39:Agricultural and environmental biology and related fields
• Research Institution: Ehime University
• Principal Investigator: Suzuki Yasutsugu 愛媛大学, 沿岸環境科学研究センター, 特定准教授 (00896087)
• Co-Investigator(Kenkyū-buntansha): 堀江 真行 大阪公立大学, 大学院獣医学研究科, 教授 (20725981)
• Project Period (FY): 2021-07-09 – 2024-03-31
• Keywords: 内在性ウイルス配列 / 媒介蚊

Outline of Final Research Achievements

Aedes mosquitoes are known to transmit numerous human pathogenic viruses, yet there are scant reports of viruses inducing severe pathology in Aedes mosquitoes themselves. This study hypothesized that ancient viruses may have possessed high pathogenicity for vector mosquitoes and employed various bioinformatics tools to explore endogenous viral elements (EVEs). In the end, we chose and performed tBLASTn searches on multiple Aedes aegypti genomes, identified EVEs with extended open reading frames (ORFs), and identified several novel EVEs. These genes were then artificially synthesized and overexpressed in Aedes aegypti cell lines and individuals with no obvious cytopathic effects or reduction in mosquito survival. Although we were not able to find pathogenic gene in the mosquitoes, our findings suggest the presence of novel EVEs with ORFs and highlight the evolved tolerance of Aedes mosquitoes to viral infections.

Free Research Field

ウイルス学、衛生昆虫学

Academic Significance and Societal Importance of the Research Achievements

多くのヒト病原性ウイルスを媒介するシマカは、自身がウイルスに感染しても重篤な病態を示さないため、蚊に病態を誘導するウイルスの同定は、その制御につながる。我々は、その探索元として、古代のウイルスに着目し、シマカのゲノムに残る内在性ウイルス配列（EVE）を様々な生命情報学ツールで探索を実施した。その結果、新たな古代ウイルス由来と考えられる遺伝子を同定し、人工合成を行った。これらの遺伝子をシマカの細胞株と個体内で発現させたが、細胞傷害や寿命の減退は見られなかった。本研究はEVE探索の適切なツール選択の重要性とシマカのウイルスに対する高い寛容性を示唆し、ウイルスと蚊の共進化の理解を深めた。