Study on the differences of glycoprotein gene between rabies virus epidemic strains from Guizhou province and vaccine strains

Objective To study the differences of glycoprotein gene (G gene) between rabies virus epidemic strains of Guizhou province in recent years and vaccine strains,and to provide scientific basis for the development of rabies vaccine and establishment of effective control and prevention measures.Methods RT-PCR assay was used to amplify the G gene of rabies positive brain tissues samples of human and dog derived from Guizhou province in recent years.The amplification products were sequenced and comparatively analyzed with that of vaccine strains by using bioinformatics software.Results Eight full-length G gene sequences were obtained by RT-PCR amplification,sequencing and splicing.The homogeny of G gene between 8 epidemic strains of Guizhou province and 9 vaccine strains were 82.0％-94.1％ and 87.6％-97.5％ on nucleotide and deduced amino acid level,respectively,and the highest homogeny were found with the human vaccine strain CTN (87.0％-94.1％ for nucleotide and 93.7.％-97.5％ for amino acid) among the 6 human rabies vaccine strains,while highest homogeny were found with strain Flury (83.9％-84.6％ for nucleotide and 91.1％-93.0％ for amino acid) among the three animal vaccine strains.Besides,among the 8 epidemic strains from Guizhou province,strain GZ09 collected in the year of 2005 was of the highest homogeny with human rabies vaccine strain CTN and animal rabies vaccine strain Flury,while strain GZ30 collected in the year of 2010 was of lowest homogeny with human rabies vaccine strain CTN and animal rabies vaccine strain Flury.Moreover,phylogenetic analysis based on the G gene indicated that the relationship of 8 epidemic strains derived from Guizhou,the 9 vaccine strains and genotype 1 Lyssavirus were clustered to a same branch.Vaccine strain CTN among the 9 vaccine strains was closest to the 8 epidemic strains,and the other 8 vaccine strains were relatively more distant from the epidemic strains of Guizhou province.In addition,phylogenetic analysis indicated that among the 8 epidemic strains from Guizhou province,strain GZ09 collectcd in the year of 2005 was of closest evolutionary relationship to CTN,while the other 7 epidemic strains were relatively more distant from CTN.Conclusion This study confirmed on the G gene level that rabies virus strains circulated in Guizhou province in recent years and the vaccine strains used in China belonged to rabies virus genotype 1,and the virus strains circulated in Guizhou province in recent years is of smallest difference with the human vaccine strain CTN and animal vaccine strain Flury.Besides,as time goes on,the difference between the epidemic strain and the vaccine strains becomes more and more obvious.The results of this study will provide scientific basis for the development of rabies vaccine and establishment of effective control and prevention measures. Key words: Rabies virus; Glycoprotein gene; Vaccine strain; Differences