In people infected with both the hepatitis B virus and the AIDS virus HIV, a widely used treatment for hepatitis also causes HIV to develop drug resistance, scientists report.
Chloe Thio of the Johns Hopkins University School of Medicine in Baltimore and her colleagues studied HIV infection in three patients who were taking the drug entecavir to treat hepatitis B, a virus that attacks the liver. The scientists found that entecavir reduced the amount of HIV in all three patients' bloodstreams.
Entecavir combats hepatitis B by inhibiting an enzyme called DNA polymerase, which plays a central role in viral replication. Thio and her team found that the drug also stymies a similar enzyme, RNA reverse transcriptase, that HIV uses to copy itself.
The team then discovered that one of the patients developed a mutated HIV strain known to resist a variety of anti-HIV drugs. To confirm the change, the scientists engineered the mutation into a lab strain of HIV and showed that