Transcellular transport of West Nile virus-like particles across human endothelial cells depends on residues 156 and 159 of envelope protein.
BACKGROUND
West Nile virus (WNV) causes viremia after invasion to the hosts by mosquito bite. Endothelial cells could play an important role in WNV spread from the blood stream into the central nervous system and peripheral tissues. Here, we analyzed the capacity of virus-like particles (VLPs) of the highly virulent NY99 6-LP strain (6-LP VLPs) and the low virulence Eg101 strain (Eg VLPs) to cross cultured human endothelial cells.


RESULTS
6-LP VLPs were transported from the apical to basolateral side of endothelial cells, whereas Eg VLPs were hardly transported. The localization of tight junction marker ZO-1 and the integrity of tight junctions were not impaired during the transport of 6-LP VLPs. The transport of 6-LP VLPs was inhibited by treatment with filipin, which prevents the formation of cholesterol-dependent membrane rafts, suggesting the involvement of raft-associated membrane transport. To determine the amino acid residues responsible for the transport of VLPs, we produced mutant VLPs, in which residues of E protein were exchanged between the 6-LP and Eg strains. Double amino acid substitution of the residues 156 and 159 greatly impaired the transport of VLPs.


CONCLUSIONS
Our results suggest that a transcellular pathway is associated with 6-LP VLPs transport. We also showed that the combination of the residues 156 and 159 plays an important role in the transport of VLPs across endothelial cells.
Department of Molecular Pathobiology, Hokkaido University Research Center for Zoonosis Control, Kita 20, Nishi 10, Kita-ku, Sapporo 001-0020, Japan. r-hasebe@vetmed.hokudai.ac.jp
Rie
R
Hasebe
Tadaki
T
Suzuki
Yoshinori
Y
Makino
Manabu
M
Igarashi
Satoko
S
Yamanouchi
Akihiko
A
Maeda
Motohiro
M
Horiuchi
Hirofumi
H
Sawa
Takashi
T
Kimura
D019943:Amino Acid Substitution; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000821:virology*; D006801:Humans; D020125:Mutation, Missense; D014759:Viral Envelope Proteins / Q000235:genetics / Q000502:physiology*; D022701:Virosomes / Q000378:metabolism; D037521:Virulence Factors / Q000235:genetics / Q000502:physiology*; D014902:West Nile virus / Q000472:pathogenicity*
D014759:Viral Envelope Proteins; D022701:Virosomes; D037521:Virulence Factors