Com plete Sequence Analysis of the Full-length Genom e of the Japanese Encephalitis Virus Attenuated Strain SA14-12-1-7

To sequence the full length genome of Japanese encephalitis virus attenuated strain SA14—12— 1—7．direct information about the genomic structure and the possible relationship to the attenuated and stability m echanism has been provided in this study．Six pairs of prim ers were designed according tO the published sequences of SA14—14—2 and SA14 strains，covering full—length genome of the JEV virus．Using RT—PCR，cDN A fragm ents Of SA14—12—1—7 strain were got and cloned into pGEM —T vector，then trans— formed into com petent TG1 hosts．The positive colones were screened and then the inserted fragm ents were sequenced．The results of sequence analysis show ed that genom e of SA14—12—1—7 strain consistes of 10976 nucleotides and containes a single open reading frame of 10299 nt which encodes a polyprotein of 3432 am ino acids．Com pared with the published sequence of SA14—14—2 and SA 14 strain，the hom ology of the nucleotide sequence and deduced am ino acid sequence were all more than 99％ ．the mutation sites were located in different regions．In E region，5 sites are the same as SA14—14—2 and other 3 sites are the same as SA14 strain．Some sites in NS3，NS5 and 3’NTR m ay relate w ith the attenuated stability．So the sequence of SA14—12—1—7 strain genome is sim ilar tO the published inform ation，several mutation sites are responsibe for the attenuation Of the virus and the virulence stability．The sequence analysis would aid in understanding attenuated mechanism of the vaccine．