The Viral And Immune Genetics Study Of Hbe Ag/HBeAb Seroconversion In Chonic Hepatitis B Patients

According to the latest World Health Organization report,more than 240 million people worldwide are chronically infected with hepatitis B. About 2%~6% gradually developed into cirrhosis and hepatocellular carcinoma(HCC) every year and an estimated 650 000 people will die annually due to CHB. The natural history of chronic HBV can be divided into immune tolerant phase, immune clearance phase, inactive phase, and reactivation phase. The natural HBe Ag seroconversion needs a long period of time and the conversion rate which treated by antiviral therapy is only about 40%.Precore(PC) and basal core promoter(BCP) mutation affected the expression and replication of viruses. The PC mutation G1896 A could code a new stop codon which terminated the HBe Ag expression. The BCP mutation(A1762T and Gl764A) results in decreased levels of the precore m RNA and therefore diminished production of HBe Ag. Recently, some genome-wide association study(GWAS) identified polymorphisms in the HAL-DP/DQ and IL28 B associated with spontaneous viral clearance in chronic hepatitis B infection.The virus factors(PC/BCP) and host factors(HLA- DP/DQ, IL28B) affected the process and outcome of chronic HBV. The genetic mechanism of spontaneous HBe Ag seroconversion is unclear. and there is no GWAS research for HBe Ag seroconversion, so we prospectively collected four groups patients includes younger age patients with HBe Ag non-seroconversion group(less than 20 years old, HBe Ag positive), younger age patients with HBe Ag seroconversion group(less than 20 years old, HBe Ag negative), older age patients with HBe Ag seroconversion group(older than 50 years, HBe Ag negative) and older age patients with HBe Ag non-seroconversion group(older than 50 years, HBe Ag positive).Based on analysis of PC/BCP variation and HLA- DP/DQ, IL28 B gene polymorphism with HBe Ag seroconversion, hoped to further prove the relationship between premature or delayed HBe Ag seroconversion with HLA-DP/DQ, IL28 B single nucleotide polymorphisms and PC/BCP variation.The main results of our study:1. A total of 437 patients with CHB were enrolled in the first stage of our research. The younger age group included 179 HBe Ag seroconversion and 106 non-seroconversion patients and the older age group included 90 HBe Ag seroconversion and 62 non-seroconversion patients. The proportion of male patients was significantly higher in younger age group with HBe Ag seroconversion than older age group with HBe Ag non-seroconversion(65.9% vs 46.7%). In all patients with normal ALT levels, ALT and HBV DNA were significantly higher in HBe Ag positive patients than HBe Ag negative patients. HBV DNA positive rate in older HBe Ag negative patients was significantly higher than that of in younger HBe Ag negative patients(42.2% vs 18.4%, χ2 =17.4, P<0.05).2. HBV strains were all wild-type without any detected mutations in PC or BPC region in younger age patients with HBe Ag non- seroconversion. About 69% cases in younger age patients with HBe Ag seroconversion occurred mutations in PC region while 25% cases occurred BCP double mutations or remained wild-type. About 24% cases in older age patients with HBe Ag seroconversion occurred mutations in BCP region and 17% cases remained wild-type. Six cases(11%) in older age patients with HBe Ag non-seroconversion showed consecutive HBe Ag positive in spite of PC mutants were detected. No significant differences of age, sex, ALT, HBV DNA and HBs Ag level were observed between patients with PC/BCP mutations and wild-type in older HBe Ag positive patients. HBe Ag titer in patients with BCP mutations was significantly lower than that of wild-type(t=-3.1,P<0.05). HBe Ag titer in patients with PC mutations was lower than that of wild-type but without statistical significance(t=-1.4,P>0.05).3. The rs12979860 T and rs8099917 G as a risk allelic, their frequency of patients with persisting positive HBV(9.0%, 8.5%) were significantly higher than that of patients with early onset transformation(3.4%, 3.3%)(P = 1.45 x 10-4, P = 3.15 x 10-4).IL28 rs12979860 CC and rs8099917 TT genotype B were significant associated with early onset HBe Ag seroconversion in chronic HBV patients(rs12979860, p = 8.74 x 10-4; rs8099917, p = 2.15 x 10-3).IL28 B haplotype GT was significant correlation with HBe Ag sustainable positive(P = 2.39 x 10-3), while IL28 B haplotype TC was significant correlation with early onset HBe Ag seroconversion(P = 2.39 x 10-3)4. There was no obvious association between HLA-DP/DQ and HBeAg spontaneousserological conversion.In conclusion, this study through the PC/BCP mutation experiment proved that the virus can reduce HBe Ag levels, and affect HBe Ag conversion rate, but the virus factors cannot fully explain HBe Ag conversion result; according to the research of relationship between premature or delayed HBe Ag seroconversion with HLA-DP/DQ, IL28 B, proved from the aspects of the host genetic IL28 B correlated with early onset HBe Ag seroconversion, but HLA- DP/DQ were found no significant correlation with early onset HBe Ag seroconversion.