| Objective: To evaluate the distribution of HBV genotype and serotype in community-based Tibetan in Tongde Qinhai and study the relationship between the genotype and the progression of liver disease. To understand the prevalence of mutant of BCP T1762/A1764 and PreC A1896 and give a preliminary analyze about the relationship between each of the mutants and factors such as genotype, status of HBeAg and Clinical outcome .Methods: 311 sera with positive HBsAg status, were selected from community-based Tibetan in Tongde Qinhai in 2006 . Fragment of S gene and C gene were achieved by PCR and sequenced directly after HBV DNA was extracted. Genotype was identified by comparing the sequences of samples with the reference sequence from GeneBank through DNASTAR. Convert nucleotide of sequences into the corresponding amino acid, then serotype was identified according to the common"α"determinant and 122, 127, 160 amino acid of S protein of HBV . Identify the mutant of BCP T1762/A1764 and PreC A1896 by comparing the sequences of samples with the reference sequence of AB033556. In the last, SAS 8.0 was used for the statistic analyze byχ2 test and Fisher's exact test .Result:1. Among 311 positive HBsAg sera, 304(97.8%) were positive in S gene by PCR , from which 298(98.0%) were successfully sequenced. 296(95.2%) were positive in C gene by PCR, from which 283(95.6%) were successfully sequenced. 271 were positive in both S gene and C gene and successfully sequenced with the ratio of 87.1% .2. Among 271 samples whose genotype could be identified, 261(96.3%) belong to recombinant between genotype C and D while 10(3.7%) belong to genotype C. As for serotype, 259(95.6%) were identified as ayw2, 10(3.7%) were identified as adr, 2(0.7%) were identified as adw2. 261 sera were recombinant between genotype C and D, including 128 male and 133 female. 10 sera were genotype C, including 6 male and4 female. The distribution of gender between different genotype appear no significant statistic difference (P=0.5745). All samples were divided into four group according to its age, they were the group younger than the 15 years old, the group older than 15 but younger than 30 years old, the group older than 30 but younger than 50 years old, the group older than 50 years old. Among the four group, 54,95,90,22 were recombinant between genotype C and D respectively , and 4,4,1,1 were genotype C respectively, there was no significant statistic difference of gender between different genotype (P=0.3261). 3. Chronic hepatitis B include four stage: immune tolerant phrase, immune clearance phase, inactive phrase, HBeAg neagtive chronic hepatitis. Out of 271 samples whose genotype could identified, 119, 90, 88, 32, which belong to the four stage respectively, was recombinant between genotype C and D, while 7, 2, 0, 1 was genotype C respectively. The constitution of clinical outcome between different genotype appears no significant statistic difference (P=0.3862).4. Among 271 samples whose genotype could be identified, 56(20.7%) mutants of BCP T1762/A1764 were discovered, including 25 male and 31 female, the difference was of no significant statistic meaning (P=0.4944). 8, 14, 23, 11 distribute among different age group, the rate of mutant rise with age increasing (P<0.005). 56, 0 belong to recombinant between genotype C and D, genotype C respectively, the former is higher than the latter in the rate of mutant (P=0.0294). 36, 20 were discovered in negative and positive HBeAg samples, the former is higher than the latter (P<0.0001). 12, 29, 8, 7 belong to the four stage of chronic hepatitis B, there was significant statistic difference (P=0.0003). The rate of mutant in positive HBeAg phase is higher than immune tolerant phrase (P<0.0001).5. Among 271 samples whose genotype could be identified, 27(10.0%) mutants of PreC A1896 were discovered, including 10 male and 17 female, the difference was no significant statistic meaning (P=0.201). 5, 10, 8, 4 distribute among different group, the difference was no significant statistic meaning (P>0.25). 27, 0 belong to recombinant between genotype C and D, genotype C respectively, the difference was of no significant statistic meaning (P=0.6053). 22, 5 were discovered in negative and positive HBeAg samples, the former is higher than the latter (P<0.0001). 4, 21, 0, 2 belong to the four stage of chronic hepatitis B, there was significant statistic difference (P<0.0001). The rate of mutant in inactive phrase is higher than immune tolerant phrase (P<0.0001).Conclusion: The predominant genotype of HBV in community-based Tongde Qinhai was recombinant between genotype C and D, while the main Serotype is ayw2. The prevalence of mutant of both BCP T1762/A1764 and PreC A1896 were relatively lower, the two mutants were related with negative HBeAg, and BCP T1762/A1764 can be regard as the biologic marker for predicting the prognosis of patients suffering from chronic hepatitis B in the area. |
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