Abstract: ObjectiveTo establish a phylogenetic tree of enterovirus 71 strains isolated in Linyi,Shandong province based on the changes of 3D region to reveal the relationship between EV71 3D and neurovirulence.MethodsEnterovirus 71 strains were isolated from 107 stool and throat swab specimens collected from Linyi People's Hospital.The nucleotide and amino acid sequences of 3D region of the strains SDLY1,SDLY11,SDLY48,SDLY96,and SDLY107 were aligned using Bioedit and MEGA 4.The phylogenetic tree,gene distance,nucleotide composition,amino acid composition,nucleotide sequence alignment,and amino acid sequence alignment were determined.Results Phylogenetic analysis of 3D region showed that the phylogeny was close within Linyi strains,especially within SDLY11,96,107,and the phylogeny was closer between Linyi strains and CoxA16 G-10 than that between Linyi strains and standard strain BrCr/70.Analysis of nucleotide composition and amino acid composition showed that composition of nucleotide A or leucine was the highest.Alignment of nucleotide and amino acid demonstrated some mutations of K and R,and 2 specific mutations for strain SDLY107,E947D and K1873R.ConclusionEvolution of 3D region of enterovirus 71 strains isolated in Linyi may be relevant to CoxA16 G-10,and two mutations of N37S and K142R may be related to the neurovirulence of EV71.