Unique Requirement for ESCRT Factors in Flavivirus Particle Formation on the Endoplasmic Reticulum

• Main Authors: Keisuke Tabata, Masaru Arimoto, Masashi Arakawa, Atsuki Nara, Kazunobu Saito, Hiroko Omori, Arisa Arai, Tomohiro Ishikawa, Eiji Konishi, Ryosuke Suzuki, Yoshiharu Matsuura, Eiji Morita
• Format: Article
• Language: English
• Published: Elsevier 2016-08-01
• Series: Cell Reports
• Subjects: flavivirus; ESCRT; TSG101; CHMP2; CHMP4
• Online Access: http://www.sciencedirect.com/science/article/pii/S2211124716310129

Flavivirus infection induces endoplasmic reticulum (ER) membrane rearrangements to generate a compartment for replication of the viral genome and assembly of viral particles. Using quantitative mass spectrometry, we identified several ESCRT (endosomal sorting complex required for transport) proteins that are recruited to sites of virus replication on the ER. Systematic small interfering RNA (siRNA) screening revealed that release of both dengue virus and Japanese encephalitis virus was dramatically decreased by single depletion of TSG101 or co-depletion of specific combinations of ESCRT-III proteins, resulting in ≥1,000-fold titer reductions. By contrast, release was unaffected by depletion of some core ESCRTs, including VPS4. Reintroduction of ESCRT proteins to siRNA-depleted cells revealed interactions among ESCRT proteins that are crucial for flavivirus budding. Electron-microscopy studies revealed that the CHMP2 and CHMP4 proteins function directly in membrane deformation at the ER. Thus, a unique and specific subset of ESCRT contributes to ER membrane biogenesis during flavivirus infection.