Analysis on M genes variation rules of SARS-CoV

  Objective   To discover the variations rules of M genes through sequencing the M gene of SARS-CoV GD322 isolate and to compare it with those of published on GenBank.

  Methods   RNA was extracted from SARS-CoV GD322 strain and used for RTPCR, then the PCR prducts were cloned into pGEMT vector and transformed DH5, with which was followed M gene sequencing.This M gene sequence and other 81 M genes published on GenBank were used to compare with the M gene of TOR2 with Clustal X, from which the variation rules of M genes were gotten.Then, predicted the turn and the possible Bcell epitopes with Protean program and analyzed the variations effect on them.

  Results   After sequencing the gene of GD322 isolate(A Y702026)and analyzing those published 81 M genes, TOR2 was selected as the reference strain.Among the 82 M genes, 36 isolates M genes were same as that of TOR2, 5 isolates syno nymous mutation and 40 isolates nonsynony mous mutation.11 nucleotide mutation sites were discovered in the 82 M genes, 9 of which were nonsy nonymous mutation and 2 synonymous mutation.The results of predicting the turn and the B cell epitopes of M genes of Frankfurt 1 and TW5 showed no differences to those of TOR2.

  Conclusion   Though the variations of SARS CoV M genes are of gradually in creasing trend during the course of epidemic spread, the total mutation rate is quite small and the M gene sequences are considerably stable, the isolates related to M hotel varied less than those with no relation to.The variations of M genes have hardly affected the antigenicity of M protein.