Genetic Diversity Of Dominant Ticks And Detection Of Specific Genes Of Brucella In Xilingol League,Inner Mongolia

Dermacentor nuttalli belongs to Ixodidae Dermacentor,which can spread many kinds of pathogens and endanger the health of animals and human beings.Dermacentor is widely distributed in Xilingol League and has become one of the dominant ticks in Xilingol League.1162 ticks collected from 14 different pastoral areas in Xilingol League were identified by morphological and molecular biological techniques,and the carrying pathogens preliminary evaluated.The main research contents and results are as follows:1.The morphological observation of ticks collected in 14 different pastoral areas of Xilinguole League from 2017 to 2018 was carried out.The dominant ticks in this area were D.nuttalli by observing the morphological characteristics of false head base,edge stack and shield plate.The similarity was more than 99%,between sequences of mitochondrial 16S rRNA and cytochrome oxidase gene(COI)to those of know D.nuttalli from GenBank.It was consistent with the res?Lts of morphological identification.The phylogenetic tree of 16S rRNA and COI genes was constructed by using Mega 6.06 software.The results showed that D.nuttalli from different areas of Xilingol was clustered on the same branch with D.nuttali at home and abroad,especially those from Xinjiang,China.2.The genetic diversity and structure of 121 of 16S rRNA gene sequences and 85 of COI gene sequences of D.nuttalli collected in Xilingol were analyzed.The content of A+T was obvious higher than that of C+G,which was accorded with the obvious at bias of insect mitochondrial DNA base.Base saturation substitution analysis showed that the two kind of genes were not saturated,suggesting phylogenetic analysis was feasible.The haplotype diversity of 16S rRNA gene sequence was 0.751(Hd?0.5),nucleotide diversity was 0.00494(?<0.5%),while the haplotype diversity of COI gene sequence was 0.874(Hd?0.5),and the nucleotide diversity was 0.00335(?<0.5%).This indicated that 16S rRNA and COI genes experienced bottleneck effect in the tick population,and then showed significant expansion again.3.Common PCR and TaqMan real-time fluorescent quantitative PCR were used to detect pathogen-specific genes of Brucella in ticks from 14 different areas.The res?Lts showed that the positive rate of Brucella pathogen was 27.54%in 1162 ticks detected by common PCR,even up to 80%in some areas Among the positive and negative res?Lts of these common PCR,50 samples were randomly selected and then detected by TaqMan real-time fluorescent quantitative PCR.The res?Lts showed that the copy number of specific genes of Brucella spp.was between 7.19 × 102-1.06 × 107 in positive and negative samples.Conclusion:Dermacentor nuttalliare one of the dominant species in the Xilingol League in Inner Mongolia.There are abundant gene haplotypes among the locusts in different regions.The D.nuttalli may be a vector organism carrying Brucella pathogens and have the potential to spread human and animal Brucella.