Claudins in viral infection: from entry to spread

Abstract

Tight junctions are critically important for many physiological functions, including the maintenance of cell polarity, regulation of paracellular permeability, and involvement in signal transduction pathways to regulate integral cellular processes. Furthermore, tight junctions enable epithelial cells to form physical barriers, which act as an innate immune mechanism that can impede viral infection. Viruses, in turn, have evolved mechanisms to exploit tight junction proteins to gain access to cells or spread through tissues in an infected host. Claudin family proteins are integral components of tight junctions and are thought to play crucial roles in regulating their permeability. Claudins have been implicated in the infection process of several medically important human pathogens, including hepatitis C virus, dengue virus, West Nile virus, and human immunodeficiency virus, among others. In this review, we summarize the role of claudins in viral infections and discuss their potential as novel antiviral targets. A better understanding of claudins during viral infection may provide insight into physiological roles of claudins and uncover novel therapeutic antiviral strategies.

Keywords: Claudins; Tight junction; Viral infection; Viral pathogenesis.

Figure 1

Homology model showing the general structure of CLDN1 as a representative claudin. Claudin signature sequence residues within ECL1 (W-GLW-C-C) are shown in red with side chains. The homology model was generated using the crystal structure of murine CLDN19 [81] as a template in SWISS-MODEL [6]. CLDN19 is closely related to CLDN1 [53]. The structure was rendered in PyMol [88]. ECL1, extracellular loop 1; ECL2, extracellular loop 2.