Pastey Manoj K, McCurdy Lewis H, Graham Barney S
Department of Veterinary Biomedical Sciences, Oregon State University, Corvallis, OR 97330, USA.
Department of Infectious Diseases, Wake Forest University School of Medicine, Charlotte, NC 28204, USA.
Microorganisms. 2025 Jul 7;13(7):1599. doi: 10.3390/microorganisms13071599.
(RSV) is a major human respiratory pathogen, particularly affecting infants, the elderly, and immunocompromised individuals. RSV exists in both spherical and filamentous forms, with the filamentous morphology associated with enhanced infectivity and cell-to-cell spread. Here, we demonstrate that RhoA, a small GTPase involved in cytoskeletal regulation, is essential for filamentous RSV morphogenesis through its role in organizing lipid raft microdomains. Rhosin, a selective RhoA inhibitor developed through structure-guided screening, disrupts GEF-RhoA interactions to block RhoA activation. The pharmacological inhibition of RhoA with Rhosin significantly reduced filamentous virion formation, disrupted RSV fusion (F) protein colocalization with lipid rafts, and diminished cell-to-cell fusion, without affecting overall viral replication. Scanning electron microscopy revealed that Rhosin-treated infected HEp-2 cells exhibited fewer and shorter filamentous projections compared to the extensive filament formation seen in untreated cells. β-galactosidase-based fusion assays confirmed that reduced filamentation corresponded with decreased cell-to-cell fusion. The biophysical separation of RSV spherical and filamentous particles by sucrose gradient velocity sedimentation, coupled with fluorescence and transmission electron microscopy, showed that Rhosin treatment shifted virion morphology toward spherical forms. This suggests that RhoA activity is critical for filamentous virion assembly, which may enhance viral spread. Immunofluorescence microscopy using lipid raft-selective dyes (DiIC) and fusion protein-specific antibodies revealed the strong co-localization of RSV proteins with lipid rafts. Importantly, the pharmacological inhibition of RhoA with Rhosin disrupted F protein partitioning into raft domains, underscoring the requirement for intact lipid rafts in assembly. These findings highlight a novel role for host RhoA signaling in regulating viral assembly through raft microdomain organization, offering a potential target for host-directed antiviral intervention aimed at altering RSV structural phenotypes and limiting pathogenesis.
呼吸道合胞病毒(RSV)是一种主要的人类呼吸道病原体,尤其影响婴儿、老年人和免疫功能低下的个体。RSV以球形和丝状两种形式存在,丝状形态与增强的感染力和细胞间传播相关。在此,我们证明,参与细胞骨架调节的小GTP酶RhoA通过其在组织脂筏微结构域中的作用,对丝状RSV形态发生至关重要。通过结构导向筛选开发的选择性RhoA抑制剂Rhosin,可破坏鸟苷酸交换因子-RhoA相互作用以阻断RhoA激活。用Rhosin对RhoA进行药理学抑制可显著减少丝状病毒粒子的形成,破坏RSV融合(F)蛋白与脂筏的共定位,并减少细胞间融合,而不影响病毒的整体复制。扫描电子显微镜显示,与未处理细胞中广泛的丝状形成相比,用Rhosin处理的受感染HEp-2细胞表现出更少、更短的丝状突起。基于β-半乳糖苷酶的融合试验证实,丝状化减少与细胞间融合减少相对应。通过蔗糖梯度速度沉降对RSV球形和丝状颗粒进行生物物理分离,结合荧光和透射电子显微镜观察,结果表明Rhosin处理使病毒粒子形态向球形转变。这表明RhoA活性对于丝状病毒粒子组装至关重要,这可能会增强病毒传播。使用脂筏选择性染料(DiIC)和融合蛋白特异性抗体的免疫荧光显微镜显示,RSV蛋白与脂筏强烈共定位。重要的是,用Rhosin对RhoA进行药理学抑制破坏了F蛋白在筏结构域中的分配,强调了组装过程中完整脂筏的必要性。这些发现突出了宿主RhoA信号在通过筏微结构域组织调节病毒组装中的新作用,为旨在改变RSV结构表型和限制发病机制的宿主导向抗病毒干预提供了一个潜在靶点。