Objective Hepatitis B virus (HBV) mutants with deletions in the S region have not well been evaluated.This study was to assay full-length of HBV DNA, to analyze the pattern, frequency and clinical factors of S region deletion of patients with chronic HBV infection.Methods Full-length sequences of HBV DNA were acquired in 59 patients who included 7 of HBV carrier, 31 of chronic hepatitis, 10 of liver cirrhosis, 6 of chronic severe hepatitis and 5 of primary carcinoma of liver.Genotype of HBV was analyzed with PCR-RFLP.Serum HBV DNA was quantitatively measures with teal-time PCR.The full genome of complete genome of HBV DNA was amplified with routine PCR and fulllength sequencing was directly performed.HBV DNA nucleotide and amino acid sequences were analyzed with bioinformatics technique analysis.Results 25.4% (15/59) of patients with chronic HBV infection had S region deletion.Pre-S gene deletion had a closedly related to genotype C.20% (3/15) patients with Pre-S gene deletion coexisted HBsAg and anti-HBs.There was significant difference compared with patients without Pre-S gene deletion (P<0.05) .Long HBV infection (coefficien 0.28, P=0.049) and antiviral therapy (coefficient-0.451, P=0.036) .Conclusion A greater frequency of Pre-S gene deletion mutants with genotype C, advanced liver disease and active viral replication are demonstrated.It is suggested that Pre-S gene deletion would leads to failure of HBV immune evasion or immunotherapy.
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