OBJECTIVETo study the relationships between hepatitis B virus (HBV ) pre-S region mutations and their genotypes and the stages of liver disease of the patients.

METHODSThe entire HBV pre-S1 and pre-S2 genes were amplified by polymerase chain reaction (PCR). The amplified products were digested by NlaIII restriction enzyme. A detecting method for pre-S2 start codon mutation was established according to the restriction fragment length polymorphism (RFLP) analysis. Pre-S region deletion was revealed by polyacrylamide gel electrophoresis (PAGE). Fourteen sera having pre-S deletions or pre-S2 start codon mutations and wild strains were directly sequenced. HBV genotypes were determined by RFLP based on S-gene PCR products. One hundred sixty serum samples were collected from patients with HBV related diseases and they were determined by the above methods. The relationships between HBV pre-S region mutations and their genotypes and the stages of liver disease of the patients were analysed.

RESULTSOf the 160 sera, genotype B and C were identified in 81 and 79 respectively. The detected ratios of pre-S2 start codon and pre-S deletion mutations were significantly higher in genotype C than in genotype B (43.04% vs 1.23%, 36.71% vs 19.75%, P<0.05, respectively). The detection rates of pre-S2 start codon mutation were significantly different in different groups: from 50.00% (HCC), 39.47% (LC), 8.00% (CH), to ASC (0). The detection rates of pre-S deletion mutations among patients with HCC (53.13%), LC (42.11%), CH (18.00%) and ASC (7.50%) also varied significantly. The results obtained from sequencing and PCR-RFLP/PAGE were completely compatible. Multivariate analysis indicated that genotype C (OR=6.26, P<0.01) and advanced liver disease (OR=11.99, P<0.01) were significant variables for pre-S mutations development.

CONCLUSIONThe pre-S2 start codon and pre-S deletion mutations are more common in genotype C than in genotype B. These mutations are closely related to the progression of liver disease.