Comparison of Nucleotide and Deduced Amino Acid Sequences of E Protein Gene of the W ild-Type Japanese Encephalitis Viurs Strain SA14 and Its Different Attenuated Derivatives

For understanding the mechanism Of neurovirulence attenuation Of the Japanese encephalitis virus(JEV)，nucleotides of the E coding region of five JE strains，one wild and four attenuated viruses， were am plified by PCR and sequenced．A comparison of the five sequences indicated that there were tO— tally twelve nucleotides and eight amino acid differences between the vaccine strain SA14—14—2(PHK一8) and its parent SA14，in which three amino acids(E一107，E一176，E一439)were different between SA14 and SA14-12—1—7，and other three amino acids(E一138，E一279，E一315)were different between SAx4-12— 1—7 and SA14-9—7 as well as SA14-5—3．The SA14-12—1—7 strain showed low neurovirulence but unstable， whereas al1 the other attenuated strains showed high stability of attenuation．Our results suggest that the mutations of E一176(I1e Va1)，E一439(Lys Arg)and E一107(Leu-+Phe)may contribute for the attenuation of neuroinvasion and neurovirulence and the m utations of E一1 38，E一279，E一3 1 5 may con— tribute tO the attenuation of the neuroviru1ence and itS stability