West Nile virus (WNV) is a blood-borne pathogen that can cause serious systemic and neurological disease in human and animals. In order for this to occur, the virus must cross multiple polarized cell layers after mosquito borne transmission. Resistance to movement of macromolecules and pathogens across epithelia and endothelia is mediated in large part by tight junctions.
A number of recent in vitro and in vivo studies have focused on how WNV crosses polarized cell layers but the collective findings do not agree with respect to the underlying mechanism. This paper suggests that that WNV infection results in targeted endocytosis of a specific subset of tight junction membrane proteins followed by microtubule-dependent transport to and degradation in lysosomes.
West Nile Virus Infection Causes Endocytosis of a Specific Subset of Tight Junction Membrane Proteins. (2012) PLoS ONE 7(5): e37886. doi:10.1371/journal.pone.0037886
West Nile virus (WNV) is a blood-borne pathogen that causes systemic infections and serious neurological disease in human and animals. The most common route of infection is mosquito bites and therefore, the virus must cross a number of polarized cell layers to gain access to organ tissue and the central nervous system. Resistance to trans-cellular movement of macromolecules between epithelial and endothelial cells is mediated by tight junction complexes. While a number of recent studies have documented that WNV infection negatively impacts the barrier function of tight junctions, the intracellular mechanism by which this occurs is poorly understood. In the present study, we report that endocytosis of a subset of tight junction membrane proteins including claudin-1 and JAM-1 occurs in WNV infected epithelial and endothelial cells. This process, which ultimately results in lysosomal degradation of the proteins, is dependent on the GTPase dynamin and microtubule-based transport. Finally, infection of polarized cells with the related flavivirus, Dengue virus-2, did not result in significant loss of tight junction membrane proteins. These results suggest that neurotropic flaviviruses such as WNV modulate the host cell environment differently than hemorrhagic flaviviruses and thus may have implications for understanding the molecular basis for neuroinvasion.