Chemotactic activity of products of Elizabethkingia anophelis derived from Aedes albopictus against RAW264 murine macrophage cell line.

Dengue viruses enter dermal macrophages which are derived from other tissues after mosquito bites. We examined chemotactic factors derived from the dengue vector mosquito, Aedes albopictus, toward a RAW264 murine macrophage cell line. We found that Elizabethkingia anophelis that was isolated from mosquitoes exhibited migration-inducing activity toward RAW264 cells. The active substances were extracted using ethyl acetate to induce chemotactic movements. Chemotactic activity was eluted in the several fractions using the reversed-phase chromatography, suggesting that multiple substances were responsible for the activity. We isolated three bacterial colonies from the wild A. albopictus mosquitoes collected in Toyama Park, Tokyo prefecture, Japan. The bacterial 16S rRNA gene sequences were the most similar to those of Lonsdalea quercina. These bacteria also exhibited migration-inducing activity toward RAW264 cells. The migration-inducing activity of mosquito bacteria might be a new aspect of mosquito-mediated viral infections.