Department of Virology and Immunology, Texas Biomedical Research Institute, San Antonio, TX, USA.
University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.
Virol J. 2018 Aug 31;15(1):135. doi: 10.1186/s12985-018-1045-0.
Currently, no FDA-approved vaccines or treatments are available for Ebola virus disease (EVD), and therapy remains largely supportive. Ebola virus (EBOV) has broad tissue tropism and can infect a variety of cells including epithelial cells. Epithelial cells differ from most other cell types by their polarized phenotype and barrier function. In polarized cells, the apical and basolateral membrane domains are demarcated by tight junctions, and specialized sorting machinery, which results in a difference in composition between the two membrane domains. These specialized sorting functions can have important consequences for viral infections. Differential localization of a viral receptor can restrict virus entry to a particular membrane while polarized sorting can lead to a vectorial virus release. The present study investigated the impact of cell polarity on EBOV infection.
Characteristics of EBOV infection in polarized cells were evaluated in the polarized Caco-2 model grown on semipermeable transwells. Transepithelial resistance (TEER), which is a function of tight junctions, was used to assess epithelial cell polarization. EBOV infection was assessed with immunofluorescence microscopy and qPCR. Statistical significance was calculated using one-way ANOVA and significance was set at p < 0.05.
Our data indicate that EBOV preferentially infects cells from the basolateral route, and this preference may be influenced by the resistance across the Caco-2 monolayer. Infection occurs without changes in cellular permeability. Further, our data show that basolateral infection bias may be dependent on polarized distribution of heparan sulfate, a known viral attachment factor. Treatment with iota-carrageenan, or heparin lyase, which interrupts viral interaction with cellular heparan sulfate, significantly reduced cell susceptibility to basolateral infection, likely by inhibiting virus attachment.
Our results show cell polarity has an impact on EBOV infection. EBOV preferentially infects polarized cells through the basolateral route. Access to heparan sulfate is an important factor during basolateral infection and blocking interaction of cellular heparan sulfate with virus leads to significant inhibition of basolateral infection in the polarized Caco-2 cell model.
目前，尚无获得 FDA 批准的埃博拉病毒病 (EVD) 疫苗或治疗方法，治疗方法主要仍是支持性的。埃博拉病毒 (EBOV) 具有广泛的组织嗜性，可感染多种细胞，包括上皮细胞。上皮细胞与大多数其他细胞类型不同，具有极化表型和屏障功能。在极化细胞中，顶膜和基底外侧膜域由紧密连接分隔，并且存在专门的分拣机制，这导致两个膜域之间的组成存在差异。这些专门的分拣功能可能对病毒感染产生重要影响。病毒受体的差异定位可以将病毒进入限制在特定的膜上，而极化分拣可以导致病毒的定向释放。本研究调查了细胞极性对 EBOV 感染的影响。
在半透性 Transwell 上培养的极化 Caco-2 模型中评估了 EBOV 在极化细胞中的感染特征。跨上皮电阻 (TEER) 是评估上皮细胞极化的指标，它是紧密连接的功能。通过免疫荧光显微镜和 qPCR 评估 EBOV 感染。使用单向方差分析计算统计学意义，显著性水平设置为 p < 0.05。
我们的数据表明，EBOV 优先从基底外侧途径感染细胞，这种偏好可能受 Caco-2 单层跨膜阻力的影响。感染发生时细胞通透性没有变化。此外，我们的数据表明，基底外侧感染的偏向可能依赖于肝素硫酸酯的极化分布，肝素硫酸酯是一种已知的病毒附着因子。用iota-卡拉胶或肝素酶处理，中断病毒与细胞肝素硫酸酯的相互作用，显著降低了细胞对基底外侧感染的易感性，可能是通过抑制病毒附着来实现的。
我们的结果表明细胞极性对 EBOV 感染有影响。EBOV 通过基底外侧途径优先感染极化细胞。获得肝素硫酸酯是基底外侧感染的一个重要因素，阻断细胞肝素硫酸酯与病毒的相互作用可显著抑制极化 Caco-2 细胞模型中的基底外侧感染。
