Clinical

HBV variant resistant to adefovir identified

Last Updated: 2006-04-26 17:00:39 -0400 (Reuters Health)

NEW YORK (Reuters Health) - Researchers have identified a variant of hepatitis B virus (HBV) with primary resistance to the reverse transcriptase inhibitor adefovir (Hepsera), a commonly used back-up drug when resistance to lamivudine (Zeffix) develops.

In a report in the April 27th issue of The New England Journal of Medicine, Dr. Wolfram H. Gerlich, from the University of Giessen in Germany, and colleagues describe three patients with chronic hepatitis B who were infected with an HBV variant with primary adefovir resistance.

Instead of having isoleucine at position 233 of the reverse-transcriptase domain, as occurs in wild-type strains, the variant had valine. All three patients responded to treatment with tenofovir (Viread) and in vitro testing confirmed viral sensitivity to this agent.

"Our observations demonstrate that some naturally occurring HBV strains are primarily resistant to adefovir," the authors write. In addition, the mutation conferring resistance was independent of lamivudine resistance, they add.

N Engl J Med 2006;354:1807-1812.