Adenovirus Fiber can Distribute Itself to the Cell Surface without Membrane Damage

Abstract

Fiber is an adenovirus (Ad) capsid protein that binds to coxsackievirus and Ad receptor. It is secreted by Ad-infected cells in the early infection stage, and it increases the permeability of the epithelial cells. Accordingly, fiber may facilitate the apical escape of Ad particles from the basolateral side in Ad-infected cells. However, its behavior in the Ad-infected cells remains unclear. Therefore, we investigated the behavior of fiber in the Ad-infected cells by fluorescence microscope analysis. Results showed that a higher proportion of fiber molecules were present in the apical side compared with that in the basolateral side, and electrical resistance, which represents cell–cell adhesion, remained unaffected in the Ad-infected cells. Furthermore, the association between fiber secretion and membrane damage was analyzed using annexin V and propidium iodide staining. We observed that fiber was distributed to the membrane surface without membrane damage. In addition, fiber distribution occurred in Ad-infected cells as well as in fiber-expressing cells. Therefore, fiber can distribute itself to the cell surface, and it plays a novel role in Ad infection. Further investigation of fiber distribution would be useful to completely elucidate Ad infection mechanism and develop antiviral strategies for Ad.