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Kazim, S.N. and Sarin, S.K. and Sharma, B.C. and Khan, L.A. and Hasnain, S.E. (2006) Characterization of Naturally Occurring and Lamivudine-Induced Surface Gene Mutants of Hepatitis B Virus in Patients with Chronic Hepatitis B in India. Intervirology, 49 (3). pp. 152-160. ISSN 0300-5526

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BACKGROUND: Besides vaccine escape or immune escape hepatitis B virus (HBV) mutants, naturally occurring and drug-induced mutations have been reported in the surface gene (S-gene) of HBV. AIM: To investigate the frequency and profile of naturally occurring S-gene mutants and the influence of long-term lamivudine therapy in patients with chronic hepatitis B (CHB). MATERIALS AND METHODS: 57 patients with histologically proven CHB, on lamivudine 100 mg/day for more than 24 months, were included. Viral DNA was extracted at baseline and from on-therapy serum samples. The region encoding the complete major hydrophilic region (MHR) and flanking regions (nucleotides 425-840) of major S-gene that overlapped with the viral polymerase was PCR amplified and sequenced. End-of-therapy response (ETR) was assessed. RESULTS: Two (3.5%) patients had naturally occurring HBV mutants, sP127S and sS143L seen in the 'a' determinant of the S-gene. Following lamivudine therapy, 14 of 57 (24.5%) patients developed 16 types of S-gene mutations (sP120S, sA128V, sS143L, sW182St., sT189I, sV190A, sS193L, sI195M, sW196L, sW196St., sS207R, sI208T, sS210E, sF219S, sF220L and sC221G). Thirteen (81.2%) of these mutations emerged downstream to the MHR. Nine of 16 types of S-gene mutations observed with lamivudine therapy were also associated with the corresponding changes in the polymerase gene. Baseline viral DNA was significantly higher (2,093 vs. 336 pg/ml; p < 0.05) among patients developing S-gene mutants and the ETR in them was significantly lower [3 of 16 (18.8%) vs. 17 of 41 (41.5%); p < 0.05]. CONCLUSIONS: Naturally occurring S-gene mutations are uncommon and are restricted to the 'a' determinant region. Mutations develop in about a quarter of the patients on lamivudine therapy, mostly downstream to the MHR. They may contribute to non-response to the antiviral therapy.

Item Type: Article
Depositing User: Dr P Divakar
Date Deposited: 29 Jul 2015 11:15
Last Modified: 29 Jul 2015 11:15
URI: http://cdfd.sciencecentral.in/id/eprint/309

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