Instituto de Investigaciones Biotecnológicas, Conicet, Universidad Nacional de San Martín, Argentina.
Instituto de Investigaciones Biotecnológicas, Conicet, Universidad Nacional de San Martín, Argentina
J Virol. 2019 Jan 17;93(3). doi: 10.1128/JVI.01776-18. Print 2019 Feb 1.
After initiation of an infective cycle, spread of virus infection can occur in two fundamentally different ways: (i) viral particles can be released into the external environment and diffuse through the extracellular space until they interact with a new host cell, and (ii) virions can remain associated with infected cells, promoting the direct passage between infected and uninfected cells that is referred to as direct cell-to-cell transmission. Although evidence of cell-associated transmission has accumulated for many different viruses, the ability of members of the genus Pestivirus to use this mode of transmission has not been reported. In the present study, we used a novel recombinant virus expressing the envelope glycoprotein E2 fused to mCherry fluorescent protein to monitor the spreading of bovine viral diarrhea virus (BVDV) (the type member of the pestiviruses) infection. To demonstrate direct cell-to-cell transmission of BVDV, we developed a cell coculture system that allowed us to prove direct transmission from infected to uninfected cells in the presence of neutralizing antibodies. This mode of transmission requires cell-cell contacts and clathrin-mediated receptor-dependent endocytosis. Notably, it overcomes antibody blocking of the BVDV receptor CD46, indicating that cell-to-cell transmission of the virus involves the engagement of coreceptors on the target cell. BVDV causes one of the most economically important viral infections for the cattle industry. The virus is able to cross the placenta and infect the fetus, leading to the birth of persistently infected animals, which are reservoirs for the spread of BVDV. The occurrence of persistent infection has hampered the efficacy of vaccination because it requires eliciting levels of protection close to sterilizing immunity to prevent fetal infections. While vaccination prevents disease, BVDV can be detected if animals with neutralizing antibodies are challenged with the virus. Virus cell-to-cell transmission allows the virus to overcome barriers to free virus dissemination, such as antibodies or epithelial barriers. Here we show that BVDV exploits cell-cell contacts to propagate infection in a process that is resistant to antibody neutralization. Our results provide new insights into the mechanisms underlying the pathogenesis of BVDV infection and can aid in the design of effective control strategies.
在感染周期开始后，病毒感染的传播可以通过两种完全不同的方式发生：（i）病毒颗粒可以释放到外部环境中，并通过细胞外空间扩散，直到它们与新的宿主细胞相互作用，和（ii）病毒粒子可以与感染细胞保持关联，促进感染细胞和未感染细胞之间的直接传递，这种传递方式称为直接细胞间传播。尽管已经积累了许多不同病毒的细胞相关传播证据，但尚未报道属 Pestivirus 成员利用这种传播方式的能力。在本研究中，我们使用了一种表达与 mCherry 荧光蛋白融合的包膜糖蛋白 E2 的新型重组病毒来监测牛病毒性腹泻病毒（BVDV）（Pestivirus 的典型成员）感染的传播。为了证明 BVDV 的直接细胞间传播，我们开发了一种细胞共培养系统，该系统允许我们在存在中和抗体的情况下证明从感染细胞到未感染细胞的直接传播。这种传递方式需要细胞-细胞接触和网格蛋白介导的受体依赖性内吞作用。值得注意的是，它克服了 BVDV 受体 CD46 的抗体阻断，表明病毒的细胞间传播涉及靶细胞上的共受体的参与。BVDV 导致了对畜牧业最重要的病毒感染之一。该病毒能够穿过胎盘并感染胎儿，导致持续性感染动物的诞生，这些动物是 BVDV 传播的储主。持续性感染的发生阻碍了疫苗的功效，因为它需要诱导接近使感染完全清除的免疫保护水平来防止胎儿感染。虽然疫苗可以预防疾病，但如果具有中和抗体的动物受到病毒的挑战，仍可以检测到 BVDV。病毒的细胞间传播允许病毒克服游离病毒传播的障碍，例如抗体或上皮屏障。在这里，我们表明 BVDV 利用细胞-细胞接触在一种对抗体中和具有抗性的过程中传播感染。我们的结果为 BVDV 感染发病机制的机制提供了新的见解，并有助于设计有效的控制策略。
