title: West Nile virus envelope protein glycosylation is required for efficient viral transmission by Culex vectors.
abstract: Many, but not all, strains of West Nile virus (WNV) contain a single N-linked glycosylation site on their envelope (E) proteins. Previous studies have shown that E-glycosylated strains are more neuroinvasive in mice than non-glycosylated strains. E protein glycosylation also appears to play a role in attachment and entry of WNV into host cells in vitro; however, studies examining how E protein glycosylation affects the interactions of WNV with its mosquito vectors in vivo have not yet been performed. We mutated the E protein glycosylation site from NYS to IYS in a previously described full-length clone of the NY99 genotype of WNV (WT), resulting in a virus that lacked the glycan at aa154. WNV-N154I replicated less efficiently than WNV-WT in Culex mosquito tissues, although the extent of the decrease was greater in Cx. pipiens than in Cx. tarsalis. Following peroral infection, mosquitoes infected with WNV-N154I were less likely to transmit virus than those infected with WNV-WT. Interestingly, all but one of the mosquitoes infected with WNV-N154I transmitted a revertant virus, suggesting that there is strong selective pressure toward E protein glycosylation. Together these data suggest that loss of the glycan at aa154 on the WNV E protein can severely restrict viral spread in the mosquito vector.
authors.affiliation: Arbovirus Laboratories, Wadsworth Center, New York State Department of Health, 5668 State Farm Road, Slingerlands, NY 12159, USA. rmoudy@wadsworth.org
authors.forename: Robin M
authors.initials: RM
authors.lastname: Moudy
authors.forename: Bo
authors.initials: B
authors.lastname: Zhang
authors.forename: Pei-Yong
authors.initials: PY
authors.lastname: Shi
authors.forename: Laura D
authors.initials: LD
authors.lastname: Kramer
mesh_terms: D000818:Animals; D002460:Cell Line; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D006224:Cricetinae; D003465:Culex / Q000821:virology*; D005260:Female; D006031:Glycosylation; D007303:Insect Vectors / Q000821:virology*; D014709:Vero Cells; D014759:Viral Envelope Proteins / Q000737:chemistry* / Q000378:metabolism*; D014779:Virus Replication; D014901:West Nile Fever / Q000635:transmission* / Q000821:virology; D014902:West Nile virus / Q000472:pathogenicity / Q000502:physiology*
chemical_list: D014759:Viral Envelope Proteins