RESUMEN
One of the strain of bivalent HFRS vaccine, Z37 strain was isolated from Rattus norvegicus and identified as SEO virus by serological test. The M segment cDNA of Hantavirus Z37 strain was obtained by reverse transcripti on and polymerase chain reaction, subsequently cloned into pGEM-T vector. The s equence of positive recombinants was determined by the method of dideoxy chain t ermination, which revealed that the M genomic segment is 3651 nucleotide in len gth with a predicated long open reading frame encoding a protein of 1133 amino acids. Comparison with HNT type (76-118, A9, HV-114 strains) indicated that th ere were 71.8%～72.1% homology at the nucleotide level, 76.2～76.7% homology at the amino acid level. Comparison with SEO type (R22,L99,80-39 strains) showed 95.3～96.1 homology at the nucleotide level, 95.3～99.2% homology at the amino acid level. The results of nucleotide and amino acid comparison indicated that Z 37 strain is SEO viruses in molecular level.