According to the genomic sequence of foreign four PLRV isolates, three pairs of specific primer were designed and synthesized.The cDNA of the ORF2a gene of PLRV-Ch was synthesized by reverse transcription and followed...According to the genomic sequence of foreign four PLRV isolates, three pairs of specific primer were designed and synthesized.The cDNA of the ORF2a gene of PLRV-Ch was synthesized by reverse transcription and followed by Polymerase Chain Reaction amplication.The synthesized 3′and 5′cDNA fragment of the PLRV-Ch ORF2a gene were inserted into pUC19 and cloned in E.coli JM109 and were sequenced respectively.The middle cDNA fragment were directly sequenced.The homology of nucleotide sequence of PLRV-Ch compared with PLRV-S (Scotland,UK),PLRV-N(Netherlands),PLRV-A(Australia) and PLRV-C(Canada) were 98.96%、98.70%、94.79%、97.5%,the homology of putative amino acid sequence are 97.97%、97.97%、89.69%、95.94%.In 3′region of ORF2a gene a slippery sequence for-1 frameshift and its downstream “stem-loop"or“pseudoknot"and upstream nucleotide sequence repeats were found.Authors suggested that the nucleotide repeat sequences charateristic for PLRV could form a tight successively folded complementary double stranded regions and hairpins.This structure possibly has something to do with-1 frameshift.The amino acid sequence of C terminus region of 70kD protein translated by motif Ⅳ has a protease charateristic motif and a helicase motif Ⅳ.The amino acid sequence of polypeptide translated by ORF2a gene undergoing frameshift has a single-stranded nucleic acid binding protein-like charateristic motif.展开更多
文摘According to the genomic sequence of foreign four PLRV isolates, three pairs of specific primer were designed and synthesized.The cDNA of the ORF2a gene of PLRV-Ch was synthesized by reverse transcription and followed by Polymerase Chain Reaction amplication.The synthesized 3′and 5′cDNA fragment of the PLRV-Ch ORF2a gene were inserted into pUC19 and cloned in E.coli JM109 and were sequenced respectively.The middle cDNA fragment were directly sequenced.The homology of nucleotide sequence of PLRV-Ch compared with PLRV-S (Scotland,UK),PLRV-N(Netherlands),PLRV-A(Australia) and PLRV-C(Canada) were 98.96%、98.70%、94.79%、97.5%,the homology of putative amino acid sequence are 97.97%、97.97%、89.69%、95.94%.In 3′region of ORF2a gene a slippery sequence for-1 frameshift and its downstream “stem-loop"or“pseudoknot"and upstream nucleotide sequence repeats were found.Authors suggested that the nucleotide repeat sequences charateristic for PLRV could form a tight successively folded complementary double stranded regions and hairpins.This structure possibly has something to do with-1 frameshift.The amino acid sequence of C terminus region of 70kD protein translated by motif Ⅳ has a protease charateristic motif and a helicase motif Ⅳ.The amino acid sequence of polypeptide translated by ORF2a gene undergoing frameshift has a single-stranded nucleic acid binding protein-like charateristic motif.
