Objective To elucidate the molecular basis on the differences of infectivity in infected cells between Sindbis virus(SINV:YN87448 virus)and Sindbis like virus(SINLV:XJ-160 virus).Methods Compare the E(glycoprotein)gene sequence and secondary structure of YN87448 virus and XJ-160 virus by bioinformatics analysis.Analyze the contribution of E gene to the biological differences between SINV and SINLV by constructing recombinant virus.Results By bioinformatics analysis,YN87448 virus and XJ-160 virus have the same genomic structure,which has 11 717 nt and 11 626 nt respectively.There are 82 amino acid differences between E gene of these two viruses,and showed scattered distribution.The main peak is basically the same for the hydrophobic of the E gene protein,but in some region existing small differences.The recombinant virus which exchanged the E gene of XJ-160 virus with YN87448 virus totally showed the biological character of YN87448 virus,either in the showing time of CPE,plaque forming time and plaque diameter,or in expression of functional proteins.Conclusion E gene plays a major role in the differences of infectivity in infected cells between SINV and SINLV,this result provide the molecular biological evidences for elucidating the biological differences between SINV and SINLV.