Abstract

Mammalian cell-derived West Nile virus preferentially infects cells expressing the C-type lectin CD209L (dendritic cellspecific ICAM-3 grabbing nonintegrin-related protein; liver- and lymph node-specific ICAM-3 grabbing nonintegrin) but not cells expressing CD209 (dendritic cell-specific ICAM-3 grabbing nonintegrin). In contrast, Dengue virus infection is enhanced in cells expressing either attachment factor. The West Nile virus envelope (E) protein contains a single N-linked glycosylation site at residue 154, whereas Dengue virus E contains sites at residues 153 and 67. We introduced a glycosylation site at position 67 into West Nile virus E. Reporter virus particles pseudotyped with this E protein infected cells using either CD209 or CD209L. We also introduced glycosylation sites at several novel positions. All sites allowed CD209L-mediated infection, but only a subset promoted CD209 use. As seen for other viruses, mannose-rich glycans on West Nile virus were required for its interactions with CD209. Surprisingly, however, mannose-rich glycans were not required for CD209L-mediated infection. Complex glycans, particularly N-acetylglucosamine-terminated structures, were able to mediate reporter virus particle interactions with CD209L. We propose that CD209L recognizes glycosylated flaviviruses with broad specificity, whereas CD209 is selective for flaviviruses bearing mannose-rich glycans. The location of the N-linked glycosylation sites on a virion determines the types of glycans incorporated, thus controlling viral tropism for CD209-expressing cells.