Authors: M B Crabtree R M Kinney B R Miller
Publish Date: 2004/12/10
Volume: 150, Issue: 4, Pages: 771-786
Abstract
The dengue 2 virus DENV2 NS1 glycoprotein contains two potential sites for Nlinked glycosylation at Asn130 and Asn207 NS1 produced in infected cells is glycosylated at both of these sites We used sitedirected mutagenesis of a DENV2 strain 16681 full length infectious clone to create mutant viruses lacking the Asn130 Asn207 or both of these NS1 glycosylation sites in order to investigate the effects of deglycosylation Ablation of both NS1 glycosylation sites resulted in unstable viruses that acquired numerous additional mutations these viruses were not further characterized Viruses altered at the Asn130 site exhibited growth characteristics similar to the wildtype WT 16681 virus in LLCMK2 cells and reduced growth in C6/36 cells Viruses mutated at the Asn207 site achieved similar titers in LLCMK2 cells compared to WT however the appearance of cytopathic effect was delayed and growth of these viruses in C6/36 cells was also reduced compared to WT virus The plaque size of mutant viruses altered at the Asn130 site did not differ from that of the WT virus while mutants altered at the Asn207 site exhibited a reduced and mixed plaque size Temperature sensitivity studies comparing the growth of the viruses at 37 °C and 39 °C showed no significant differences compared to the WT virus Immunofluorescent antibody staining of infected cells showed that for WT 16681 virus or the Asn130 site mutant viruses NS1 was located throughout the cytoplasm however Asn207 site mutant virus NS1 protein appeared to be localized to the perinuclear region Viruses deglycosylated at either site exhibited a significant reduction in mouse neurovirulence compared to the WT virus The results of our studies indicate that glycosylation of the DENV2 virus NS1 protein may influence NS1 protein processing/transport as well as the pathogenicity of the virus
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