Effects of N-linked glycosylation on specific cell fusion in rubella virus / 中华微生物学和免疫学杂志

ABSTRACT

Objective To explore the effects of glycosylation in E2 and E1 protein on specific cell fusion in rubella virus(RV)strain JR23.Methods Site-directed mutagenesis was used tO obtain mutants containing new enzyme sites on the E2 and E1 gene of RV JR23.All the mutants and wild type proteins were expressed in BHK21 cells and treated with acid medium to induce specific cell fusion.The fusion functions were assayed with Giemsa staining and reporter gene method for qualitative and quantitative analysis,respectively.Expression efficieneies of mutant proteins on cell surface were quantified with fluorescence-activated cell sorter(FACS).Hemadsorption assays were performed to detect binding activity of mutant proteins qualitatively and quantitatively.Results Mutant proteins E2 N53G,S73I and S131V had 62.73%,66.66%and 55.12% of fusion activities,and E1 T78A,T179A and T211A had 66.93%,87.33%and 90.18%of fusion activities,respectively,as compared with the wild type protein.The FACS indicated that the expression efficiencies of all the mutant proteins except E2 S131V were lower than that of the wild type protein.Hemadsorption assays demonstrated that binding abilities of E2 S73I and E1 T78A decreased slightly,but that of the other four mutant proteins Wns almost same as the wild type protein. Conclusion Glycosylation on E2 N53,N71,N129 and E1 N76 were important for the specific cell fusion,but E1 N177 and N209 were almost not.