Studies On The Epidemiology Of Canine Rabies In Xiangxi District Hunan Province

The prevalence of plagues in Xiangxi, which is a remote district in Hunanprovince, has its own characteristics. In this area of Hunan, rabies occurred at arelatively high level. In order to study the situation of rabies virus carried by domesticdogs with healthy appearance in Xiangxi, 38 brain tissue samples collected fromplaces of epidemic focus in September, 2005 and 168 brain tissue samples frommarkets in January, 2006 were detected with RT-PCR and direct fluorescent antibodytest (FAT). Among them five samples were positive. Then five wild rabies virusstrains were isolated by the mice inoculation test (MIT). Among those five positivesamples, four samples, accounting for 10.5% (4 of 38), were from the places ofepidemic focuses, and one sample accounting for 0.59% (1 of 168) were from markets.The rate of occurrence of rabies virus in epidemic focuses was in accord with that ofother domestic reports, but it was much lower in samples from markets. In this papera discussion was made on whether the lower rate of detection of rabies virus wascontributed by the relatively remote environment or by the winter season whensamples were collected.N gene and G gene were amplified by RT-PCR, and then sequenced. Sequencecomparison revealed that the homogeny of N gene and G gene was respectively97.1～98.7% and 96.0～98.7% in nucleotide level, and 98.4～99.3% and 98.1～99.0% in amino acid level among the five isolates. The sequence comparison andphylogenetic analysis showed that all five strains belong to genotypeⅠlyssavirus andhad close genetic relationship.Data from the sequences of N gene and G gene on five isolates of rabies virusshowed that they had higher homology with the known home isolates from Hunan,Hubei,Jiangxi,Jiangsu,Guangxi,Henan,Anhui,Guizhou,Chongqing. Sequencecomparison revealed that the homogeny of N gene and G gene was respectively88.5～98.4% and 86.7～98.7% in nucleotide level, and 97.3～99.3% and 94.7～99.0% in amino acid level. The result showed that five wild strains from Xiangxi wererelatively close genetic relationship with that of other foreign strains.The sequence comparison showed that they had high homology with the foreignisolates from Indonesia,Thailand,Malaysia,and the homogeny of N gene and G genewas 88.0～92.2% and 85.4～92.4% in nucleotide level, and 96.9～97.9%and93.7～96.8% in amino acid level respectively; and had lower homology with the knownforeign isolates from USA,Canada,Austrilia,India,Korea,France,Germany, Hungary,Russia,Poland,Ethiopoia,the homogeny of N gene and G gene was 85.8～88.5% and 80.6～84.8% in nucleotide level, and 96.7～98.7% and 90.5～93.9%inamino acid level respectively, the data of analysis showed that all five wild strainswere closely related with from Southeast Asia partial strains, and were diverged fromAmerica,Austrila,Europe,Africa and Asia partial strains.The homogeny of N gene and G gene on five isolates of rabies virus was 86.2～89.9% and 80.5～86.1% in nucleotide level, and 94.5～98.4% and 87.9～92.9% inamino acid level respectively with vaccine strains CTN,3aG,PV,ERA. A analysisshowed that the result of other domestic strain were closely related with that of theisolates from Xiangxi. These differences provide information that the domesticvaccine had better protection, and give a guide on preventing and controlling rabies inXiangxi.