Biological Characteristics Of Dominant Ticks-Dermacentor Nuttalli In Inner Mongolia And Their Potential Risk Of Transmission Of Human And Animal Brucellosis

The natural climate in Inner Mongolia is suitable for the survival of ticks.With the change of global climate,the activities of vector insects and other vector organisms are more frequent,and the D.nuttalli is one of the main varieties of ticks in this area.As we all know,ticks can carry a variety of pathogens,leading to the spread of various animal diseases.After a clinical investigation found that some of the old diseases such as Brucellosis and streptococcal disease have a renewed trend.This unexplained epidemic situation may be associated with frequent activities such as ticks and other vector organisms.The details of this study are as follows:Methods:During the period 2015-2016,about 15 pasture collection sites were collected from Hulunbuir area,Inner Mongolia,and about 2120 samples of ticks were collected from sheep surface or pasture.The traditional morphological method and molecular biology identification method(PCR method)16S rRNA and ITS2 gene)were analyzed comprehensively,and the types of ticks were accurately identified.The polymorphism of 16S rRNA gene was analyzed by Genetyx-Version 6 biological software.Using Mega 6.06 software,the sequencing results were compared with those of the known insect tick 16S rRNA gene and ITS2 gene in the GenBank database.The genomic DNA of ticks was extracted and the specific gene of Brucellosis was detected by routine PCR method.The results were analyzed statistically.To further elucidate the problem,we collected the sucked blood of the female ticks back to the laboratory for artificial incubation,extraction of its ticks(adults,nymphs,larvae and eggs)of the genomic DNA,the same method to detect Brucella-specific gene products.The TaqMan real-time PCR method was used to detect the infection of Brucellosis pathogens in the ticks,and the TaqMan real-time PCR was used to detect the positive and negative samples in the conventional PCR method.And the number of copies of the Brucella-specific gene in the ticks were determined.Results:Based on the observation of characteristic structures such as basis capituli,scutum,coxa,festoons and anus groove of ticks,according to the typical morphological characteristics of D.nuttalli,such as Walker,we found that the ticks collected The 16S rRNA and ITS2 gene genetic phylogenetic trees drawn from Mega 6.06 software show that the ticks collected by us are on the same branch as the known D.nuttalli from Xinjiang,Jilin,Hebei and Russia,and the morphological results showed that there were significant genetic polymorphisms among the ticks in 15 different regions.The conventional PCR method was found in the 15 different regions of the ticks.The results showed that there was a significant genetic polymorphism among the ticks in 15 different regions.The results showed that the positive rate of ticks collected from 15 sampling points was at least 50%,and in some cases even more than 90%.25 DNA samples were randomly selected in the positive and negative samples of conventional PCR results.The results of the Real Time PCR test showed that 50 samples showed positive results regardless of whether the conventional PCR test results were positive or not,and Bruce The lowest number of specific gene copy numbers was 16.39(Ct value was 37.07),the highest was 2.4x105(Ct value was 23.67),and Bruce was detected in genomic DNA samples of eggs,larvae and nymphs Brucella-specific gene products.Conclusion:D.nuttalli was the dominant type of ticks in the Hulunbuir region of Inner Mongolia from March to July,and there was a rich genetic polymorphism among ticks from different regions.The host body to suck the blood of the D.nuttalli almost all can bring Brucella,the more serious consequences is D.nuttalli may be transmitted by the egg vertical Brucellosis.D.nuttalli may be a new vector of Brucella and have the potential to spread human and animal Brucellosis.