The cloning and comparative study of full-length HBV genomes from serums before and after treatment with lamivudine in a patient with hepatitis B / 中华传染病杂志

ABSTRACT

Objective To compare the structural genome variations of lamivudine resistant HBV strain from a patient with acute exacerbation after lamivudine therapy with pretretment HBV strain. Methods Full length genomes of two HBV strains before lamivudine treatment and after occurring severe acute exacerbation during lamivudine treatment were cloned and sequenced in a patient with chronic hepatitis B. Nucleotide sequence and predicted amino acid sequences of 4 open reading frames in two HBV strains were analyzed. Results Compared with pretreatment full length HBV genome, there were 30 amino acid substitutions in four ORFs of lamivudine resistant HBV strain, including substitution of valine for methionine at residue 550(M550V)accompanied by substitution of methionine for leucine at residue 526(L526M). The numbers of amino acid substitutions in ORF P, X, S, Precore/Core were 10(1.19%), 4(2.60%), 8( 2.00%) and 8 (3.77%) respectively. The total variation rate along the whole HBV genome was 1.86%. A G→A change at nucleotide position 1898 resulted in a precore stop codon and led to lack of HBeAg expression; At the preS2 initiation codon ATG was changed to ATA which caused the loss of preS2 protein expression. Some amino acid changes occurred within the known CTL, B or T cells epitopes.Conclusions In a patient with severe acute exacerbation during lamivudine therapy, together with 29 additional amino acid substitutions were detected outside the YMDD motif in the lamivudine resistant HBV strain.