Carrying Rate And Molecular Epidemiology Of Hepatitis B Virus In The Ali Region,tibet

ObjectiveHepatitis B virus(HBV)belongs to the family Hepadnaviridae,with a circular,partially double-stranded DNA genome,which is the causative agent of hepatitis B virus infection.Worldwide infection with HBV poses a serious threat to public health.The geographical position of Ali Region,Tibet is very special which is located in the southwest border of China and adjacent to Nepal,India and other neighboring countries.In addition,the Ali region is a relatively closed geographical environment,with much land,few people,and inconvenient traffic.Poor living and medical conditions make the HBV infection rate of the Ali Region significantly higher than that of other regions.So far,only few studies about HBV in the Ali area have been reported.With the development of molecular biology,there have been more and more studies describing HBV genotypes.The epidemiology,disease prognosis,and treatment and prognosis effect of HBV infections are associated with HBV genotypes.In this study,we collected the blood samples of of thet Tibetan residents in the Ali area,detected of HBV carrying rate and the infection rate,and performed virus isola-tion and bioinformatics analysis of the HBV genomes.Our study will provide an important scientific basis for the prevention and control of HBV infections in the Ali region,Tibet.Method5mL venous blood samples of 2749 Tibetan residents(929 urban residents,including 469 male,460 female;1820 farmers and herdsmen,including 1078 male,742 female)living in the Ali area were collected and detected using enzyme-linked immunosorbent assay method(ELISA).Five serological markers of HBV were measured,the serological markers of hepatitis B virus surface antigen(HBsAg),hepatitis B virus surface antibody(HBsAb)and hepatitis B virus e antigen(HBeAg),hepatitis B virus e antibody(HBeAb)and hepatitis B core antibody(HBcAb),respectively.SPSS19.0 was used for statistical analysis.Then,total DNA of serum samples of the patients with HBV positive markers was extracted.The two primers,f1(1400bp)and f2(1800bp),were used to amplify HBV DNA using PCR.The PCR products were used for sequencing.Bioinformatics softwares,DNAMAN,DNAStar,MEGA,and Figtree,were to construct the phylogenetic trees for genotyping.ResultThe carrying rate of HBV in Tibetan population in the Ali area of Tibet is as high as 20.33%,whereas only approximately 23.43% of the people with immunity.The infection rate is approximately 26.12%,and the susceptible population is approximately 50.45%.Among them,there were significant differences in HBV carrying rate,immunity,infection rate and susceptibility rate between urban residents and farmers.However,there was no significant difference in HBV carrying rate,infection rate and susceptibility rate between male and female residents in urban areas,but the level of male immunity was significantly lower than that of female.The HBV carrying rate,immunity and infection rate of male and female farmers were significantly higher than those of female,but there was no significant difference in susceptibility.53 whole genome sequences were obtained,among which one(2%)belongs to genotype D(sub-genotype D3),52(98%)belong to genotype C.All of the genotype C strains were HBV C/D recombinants,with 35 strains(66%)belonging to CD1 recombinant type and 16 strains(30%)belonging to the CD2 recombinant type.Conclusion1.The carrying rate of HBV in Tibetan population in the Ali area,Tibet was 20.33%,which was significantly higher than that of the average level of China,whereas the immunization rate was lower than the national level.2.The HBV carrying rate,immunity and infection rates of male and female farmers were significantly higher than those of females,and there was no gender difference in HBV carrying rate,infection rate and susceptibility rate among urban residents.3.The great majority of HBV strains from the Ali region belonged to genotype C(98%),only few strains belonged to genotype D(2%).4.There are extensive genetic recombinations between genotypes C and F in the HBV genomes isolated from the Ali region.All of the strains belonging to genotype C were C/D recombinants,including two recombination types: CD1(69%)and CD2(31%).