Relationship Between HBV Genotypes And Clinic Features, Population Dynamics Of HBV In Chongqing, China

Objective:The study has investigated the distribution of HBV genotypes in Chongqing and explored the relationship between genotypes and age, gender, liver function, HBe Ag positive rate, the level of viral replication, clinical medicine, clinical phenotypes, HBV S gene mutations of HBV infected person, hopes to provide a theoretical basis for diagnosis, treatment and prevention of HBV in this region of Chongqing. It also researched the population genetics of HBV and calculated the population genetics structure of HBV in Chongqing, to speculate the possibility of HBV outbreak. Methods: 768 persons, who HBs Ag are positive and come from eight regions of Chongqing, have been selected. The demographic information and the data of diagnosis and treatment have been extracted from electronic medical record. HBV S gene sequences which achieved by the way of PCR and direct sequencing, as well as A-H Standard sequences have been used to construct the phylogenetic tree by online genotyping software and MEGA5.0. The study analysised the HBV genotypes and S gene mutations, explored the correlation between genotypes and clinical features, S gene mutation. Had done genetic analysis of HBV populations in different genotypes and different regions by the method of phylogenetics and population genetics, to explore the expansion of HBV among various genotypes and different regions of Chongqing.Results: 1. There are 528 in 768 HBs Ag positive serum samples that measured HBV S gene sequence successfully. Among which, genotype B is 346 cases(65.53%), genotype C is 181 cases(34.28%), genotype D is 1 case(0.19%), no other genotype. 2. Genotype B and C have little difference in gender, age, the load of HBV DNA and clinical medication, have no statistical significance(P> 0.05). 3. The rate of abnormal ALT(>40IU/L) and HBe Ag positive rate among infected person who with genotype C are obviously higher than genotype B(P<0.05). The proportion of genotype C in LC/HCC group is higher than ASC group and CHB group(P<0.05), The proportion of genotype B in ASC group and CHB group is higher than LC/HCC group(P<0.01). 4. There are a large number of mutations in different cell epitopes of HBV S gene among genotype B and C. The mutations of genotype B mainly contain I110 L, P120 T, K122 R, T126 A / S, P127 T, Q129 H / R, M133 L, T140 N, the mutations of genotype C mainly contain Y100 C, Q101 R, T113 S, S114 T, I126T/N/S, G130 N, F134 L, G131 N, S143 T. P120 T, K122 R has been found only in genotype B, T113 S only has been found in genotype C. 5. There are 140 cases(140/346) mutations in genotype B and 84 cases(84/181) mutations in genotype C in HBs Ag MHR, there are no significant difference in mutation rate(P> 0.05). Presence of single-mutation and multi-mutation, the rate of multi-mutation in genotype C is 38.1%(32/84), higher than genotype B(17.9%,25/140), whic has statistical significance(P <0.01). 6. The results of gene sequence alignment showed there are 189 gene mutation sites and 250 hap in the 346 genotype B with 531-bp S gene. H is 0.978, ranged from 0.895 to 0.999 in various regions, π is 0.01644, ranged from 0.02628 to 0.00694 in various regions. There are 150 gene mutation sites and 163 hap in the 181 genotype C in 525-bp S gene. H is 0.999, ranged from 0.992 to 1 in various regions, π is 0.02051, ranged from 0.01788 to 0.02604 in various regions. 7. The BSP of genotype B and C in different regions showed the bayesian day line is prone to rise, the value of neutrality tests(Tajima’s D and Fu’s Fs) are negative, the mismatch distribution analysis in most regions are unimodal inverted bell-shaped distribution. A comprehensive analysis showed that HBV population in Chongqing has gone through a process of expansion in the past 10 years, some areas even expand 10 times, only few areas had not obvious expansion of genotype C(Qianjiang District, Hechuan District, Shapingba District). Conclusion: 1 genotype B is the dominant genotype in Chongqing, accounting for 65.53%. 2. Genotype C with more virulence than genotype B, easily lead to liver cirrhosis and hepatocellular carcinoma. 3. HBV S gene has a large number of mutations in different cell epitopes, may lead to the change of antigenicity and immunogenicity and infected people with HBs Ab positive. 4. The rate of multi-mutation in genotype C is higher than genotype B, and that may affect HBV pathogenicity and the treatment and prognosis of patients. 5. The haplotype diversity and nucleotide polymorphism are high both in genotype B and C, suggesting that HBV has rich genetic diversity and strong ability to survive, the genotype C is higher than genotype B. 6. HBV population of genotype B and C in Chongqing are experiencing expansion, and with the possiblility of outbreak in the future. We need to do further develop large-scale molecular epidemiology research and make early warning.