Siemann David N, Strange Daniel P, Maharaj Payal N, Shi Pei-Yong, Verma Saguna
Department of Tropical Medicine, Medical Microbiology and Pharmacology, John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu, Hawaii, USA.
Department of Biochemistry and Molecular Biology, Department of Pharmacology and Toxicology, and Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, Texas, USA.
J Virol. 2017 Oct 27;91(22). doi: 10.1128/JVI.00623-17. Print 2017 Nov 15.
Confirmed reports of Zika virus (ZIKV) in human seminal fluid for months after the clearance of viremia suggest the ability of ZIKV to establish persistent infection in the seminiferous tubules, an immune-privileged site in the testis protected by the blood-testis barrier, also called the Sertoli cell (SC) barrier (SCB). However, cellular targets of ZIKV in human testis and mechanisms by which the virus enters seminiferous tubules remain unclear. We demonstrate that primary human SCs were highly susceptible to ZIKV compared to the closely related dengue virus and induced the expression of alpha interferon (IFN-α), key cytokines, and cell adhesion molecules (vascular cell adhesion molecule 1 [VCAM-1] and intracellular adhesion molecule 1 [ICAM-1]). Furthermore, using an SCB model, we show that ZIKV was released on the adluminal side of the SCB model with a higher efficiency than in the blood-brain barrier model. ZIKV-infected SCs exhibited enhanced adhesion of leukocytes that correlated with decreases in SCB integrity. ZIKV infection did not affect the expression of tight and adherens junction proteins such as ZO-1, claudin, and JAM-A; however, exposure of SCs to inflammatory mediators derived from ZIKV-infected macrophages led to the degradation of the ZO-1 protein, which correlated with increased SCB permeability. Taken together, our data suggest that infection of SCs may be one of the crucial steps by which ZIKV gains access to the site of spermatozoon development and identify SCs as a therapeutic target to clear testicular infections. The SCB model opens up opportunities to assess interactions of SCs with other testicular cells and to test the ability of anti-ZIKV drugs to cross the barrier. Recent outbreaks of ZIKV, a neglected mosquito-borne flavivirus, have identified sexual transmission as a new route of disease spread, which has not been reported for other flaviviruses. To be able to sexually transmit for months after the clearance of viremia, ZIKV must establish infection in the seminiferous tubules, the site of spermatozoon development. However, little is known about the cell types that support ZIKV infection in the human testis. Currently, there are no models to study mechanisms of virus persistence in the seminiferous tubules. We provide evidence that ZIKV infection of human Sertoli cells, which are an important component of the seminiferous tubules, is robust and induces a strong antiviral response. The use of an Sertoli cell barrier to describe how ZIKV or inflammatory mediators derived from ZIKV-infected macrophages compromise barrier integrity will enable studies to explore the interactions of other testicular cells with Sertoli cells and to test novel antivirals for clearing testicular ZIKV infection.
在病毒血症清除数月后，人类精液中出现寨卡病毒（ZIKV）的确诊报告，这表明ZIKV能够在生精小管中建立持续感染，生精小管是睾丸中一个受血睾屏障（也称为支持细胞屏障，SCB）保护的免疫特权部位。然而，ZIKV在人类睾丸中的细胞靶点以及该病毒进入生精小管的机制仍不清楚。我们证明，与密切相关的登革病毒相比，原代人类支持细胞对ZIKV高度敏感，并诱导α干扰素（IFN-α）、关键细胞因子和细胞黏附分子（血管细胞黏附分子1 [VCAM-1]和细胞间黏附分子1 [ICAM-1]）的表达。此外，使用支持细胞屏障模型，我们发现ZIKV在支持细胞屏障模型管腔侧的释放效率高于血脑屏障模型。感染ZIKV的支持细胞表现出白细胞黏附增强，这与支持细胞屏障完整性降低相关。ZIKV感染不影响紧密连接和黏附连接蛋白如ZO-1、闭合蛋白和连接黏附分子A（JAM-A）的表达；然而，将支持细胞暴露于ZIKV感染的巨噬细胞产生的炎症介质会导致ZO-1蛋白降解，这与支持细胞屏障通透性增加相关。综上所述，我们的数据表明，支持细胞感染可能是ZIKV进入精子发生部位的关键步骤之一，并将支持细胞确定为清除睾丸感染的治疗靶点。支持细胞屏障模型为评估支持细胞与其他睾丸细胞的相互作用以及测试抗ZIKV药物穿越屏障的能力提供了机会。寨卡病毒是一种被忽视的蚊媒黄病毒，最近的疫情已将性传播确定为一种新的疾病传播途径，其他黄病毒尚未有此报道。为了能够在病毒血症清除数月后进行性传播，ZIKV必须在精子发生部位生精小管中建立感染。然而，对于支持人类睾丸中ZIKV感染的细胞类型知之甚少。目前，尚无研究病毒在生精小管中持续存在机制的模型。我们提供的证据表明，人类支持细胞（生精小管的重要组成部分）感染ZIKV的情况很严重，并诱导强烈的抗病毒反应。使用支持细胞屏障来描述ZIKV或ZIKV感染的巨噬细胞产生的炎症介质如何损害屏障完整性，将使研究能够探索其他睾丸细胞与支持细胞的相互作用，并测试用于清除睾丸ZIKV感染的新型抗病毒药物。
