RESUMO
Objective To investigate the relation between a set of single nucleotide polymorphisms (SNP) in core gene of HBV in chronic hepatitis B patients and HBV DNA levels. Methods PCR restriction fragment length polymorphism(PCR-RFLP) assay and restriction enzyme Tsp509I were adopted to determine HBV SNP in HBV core gene. Nucleotide sequences of core gene were determined using the dideoxy chain termination method. HBV DNA levels were quantitated with real-time PCR. Results Five typical RFLP patterns, RFLP-C, RFLP-D, RFLP-E, RFLP-G and RFLP-C/G mixture were found and the distribution of HBV RFLP patterns was as follows: C, 61. 5% ; D, 2. 6% ; E, 9.6%; G, 16.7%; C/G mixture, 9.6%. Five SNPs, A165T, A336C, A336T, T337C and T385C, were found to be associated with RFLP patterns change and only SNP A336C or A336T caused the substitution of Glu-83 with Asp in HBcAg. The serum HBV DNA levels in RFLP-C group were higher than that in RFLP-G (P =0. 02) and RFLP-C/G group(P = 0. 006) , respectively, furthermore, the positive rate of serum ALT in RFLP-C/G group was lower than that in RFLP-C, RFLP-E and RFLP-G group, respectively. Under the condition of HBeAg-positive, the serum HBV DNA levels in RFLP-C group were higher than that in RFLP-G (P = 0. 015) and RFLP-C/G group(P =0.008) , respectively. Conclusion PCR-RFLP used in this study can be adopted to determine HBV SNPs, not genotypes in Chinese patients with chronic hepatitis B. The serum HBV DNA level in RFLP-C group higher than that in RFLP-G or RFLP-C/G group maybe associated with amino acid mutation, Glu83 Asp.