区域流行背景下布鲁氏菌的分子特征与系统发育分析OA

To investigate the genetic characteristics of Brucella in a specific region(Gansu Province)and identify the species/strains responsible for human infections,as well as to reveal the molecular epidemiological patterns.This study collected tissue samples from aborted cattle(n=324)and aborted sheep and goats(n=618),along with blood samples from humans in close contact with these animals.Following initial screening by fluorescence PCR,Brucella strains were isolated and systemat-ically analyzed using AMOS-PCR,biochemical identification,MLVA-16 typing,MLST,and whole-genome se-quencing.A total of 14 Brucella strains were isolated,including 12 B.melitensis biovar 3 and 2 B.abor-tus biovar 3.MLVA-11 analysis revealed that all B.melitensis isolates belonged to genotype 116,which is part of the Eastern Mediterranean lineage and represents the dominant circulating population in this region.MLST analysis showed that all B.melitensis isolates were of sequence type ST8,consistent with the prevalent types in neighboring areas.The concordance between conventional identification and MLVA-16 genotyping confirmed that the human-derived isolates shared identical genotypes with the sheep-derived isolates,indicating that sheep were the primary source of human Brucella infections.In conclusion,B.melitensis biovar 3 is the main causative agent of animal brucellosis in this region,with genotype 116 and sequence type ST8 as the dominant populations,and infected sheep constitute the key source of local human infections.