AI Insight
Researchers discovered that atlastin-2 (ATL2), a cellular protein that organizes endoplasmic reticulum membranes, is essential for flavivirus replication. The study shows that ATL2's membrane tethering function—but not its membrane fusion capability—is critical for organizing viral replication organelles (vROs) where flaviviruses like dengue and Zika replicate inside host cells. When ATL2 was depleted or inhibited using synthetic peptides, viral replication decreased significantly and immune responses increased, suggesting this protein could be a therapeutic target.
Why it matters
This finding identifies a potential new approach for treating flavivirus infections, which affect approximately 400 million people annually worldwide. By targeting ATL2's membrane tethering activity with synthetic peptides, it may be possible to develop broad-spectrum antiviral therapies against multiple flaviviruses without directly targeting the virus itself, potentially reducing drug resistance.
Understand the Science
by Jonathan Einterz Owen, Cheyanne Lynn Bemis, Qingyi Wang, Ambarish C. Varadan, Jacob W. Vander Velden, Laura Andačić, Olus Uyar, Mansi Gupta, Christopher D. Scharer, Laurent Chatel-Chaix, Pietro Scaturro, Mehul S. Suthar, Christopher J. Neufeldt
Flaviviruses (genus Orthoflavivirus) are arthropod-borne viruses which cause approximately 400 million annual global infections in humans. Flavivirus infection requires cellular machinery to facilitate replication and spread. All known flaviviruses replicate in association with the host endoplasmic reticulum (ER), where genome replication is confined within virus-induced ER invaginations called viral replication organelles (vROs). Despite the central role of these structures during flavivirus infection, the mechanisms underlying vRO biogenesis remain undefined—particularly the membrane rearrangements required for their formation. In this work, we report a conserved role for a cellular ER remodeling protein, atlastin-2 (ATL2), in the organization of vROs within infected cells. Using confocal and electron microscopy, we show that ATL2 depletion leads to a reduction in vRO spatial distribution in flavivirus-infected cells. Changes in vRO distribution corresponded with a decrease in virus production and robust induction of innate immune responses. We also demonstrate that ATL2 accumulates in areas of vRO formation during flavivirus infection. Critically, mutational analysis showed that a tethering-competent but fusion-defective ATL2 mutant was sufficient to rescue DENV and ZIKV replication in ATL2-knockout cells. Finally, targeting of ATL2 activity using synthetic peptides significantly reduced DENV replication in both immortalized and human primary cells, suggesting a possible avenue for targeting host ER functions to limit flavivirus replication. Taken together, these results show that membrane tethering plays a critical and conserved role in flavivirus infection, functioning to organize membranes for vRO biogenesis and limit cellular immune activation. Importantly, we provide evidence that ATL2-mediated membrane organization can be targeted to inhibit viral replication.
Source: Atlastin-2-mediated endoplasmic reticulum membrane tethering is critical for flavivirus replication