Evolution of Primary and Compensatory Lamivudine-Resistance Mutations during Long-term Lamivudine Treatment in Chronic HBV-Infected Patients Assessed by a Line Probe Assay

Innogenetics N.V., Industriepark Zwijnaarde 7/4, B-9052 Ghent, Belgium; Department of Medicine, The University of Hong Kong, Queen Mary Hospital, Hong Kong, China

^* To whom correspondence should be addressed. Email: fred_shapiro{at}innogenetics.com.

	Abstract

With the availability of more potent nucleotide/nucleoside analogues, early detection of drug-resistance mutants of hepatitis B virus (HBV) are important for strategic treatment of chronic hepatitis B. We studied 336 serum samples from 80 patients chronically infected with HBV, receiving lamivudine treatment, for the presence of lamivudine-resistance mutations at codons 80, 173, 180, and 204 of the HBV polymerase. Sequencing data were compared with results generated by the INNO-LiPA HBV DR v2, a line probe assay (LiPA) covering wild-type and mutant motifs for resistance mutations to lamivudine and adefovir dipivoxil. This method provided at least the same information as sequencing in 99.1% of all codons analyzed. Based on LiPA results, 20 of 80 patients developed a lamivudine-resistance mutation after one year. In all 20 patients, the mutation occurred in the YMDD motif at position rt204 (M204V/I) either with or without the compensatory mutation at position rt180 (L180M). A compensatory mutation at position rt80 (L80V/I) was detected in half of these patients. After 36 months, a compensatory mutation was seen at position rt173 (V173L) in 3/15 patients. Time-to-event survival analysis indicated a 2.8 times greater chance for LiPA to detect a given mutation than sequencing at any moment in time (hazard ratio 2.8, 95% C.I. [1.79;4.41]; p<0.0001). These results demonstrate that a highly sensitive and specific assay such as the INNO-LiPA HBV DR v2 can precociously detect and monitor the emergence of primary and compensatory lamivudine-resistance mutations in patients chronically infected with hepatitis B, and is more sensitive than sequencing.