Mutations associated with drug resistance and prevalence of vaccine escape mutations in patients with chronic hepatitis B infection.

The Brazilian public health system (SUS) has provided antiviral drugs for chronic hepatitis B treatment for over 10 years, but a system for monitoring for drug-related resistance mutations is not available. Determine the presence of HBV mutations associated with resistance to nucleos(t)ide analogs among 81 patients with chronic HBV infection in Salvador-BA-Brazil. HBV-DNA was PCR amplified with primers deduced from the rt domain at the HBV P gene, the sequence extended 1032 bp (from amino acid 1 to 344-rt domain). Those sequences were submitted to the HBV drug resistance database to retrieve each mutation according to the genotype. HBV genotype A1 (85.2%) was the most prevalent, followed by genotype A2 (4.9%), F (6.2%), and C1, D2, and D4 (1.2% each). Six patients (7%) exhibited resistance mutations to LAM, ETV, and TDF: two with patterns L180M + M204V and four with other different patterns: L80I + L180M + M204I; L80V + L180M + M204V; M204I; A194T. All of these mutations were present in patients with genotype A (four A1 and two A2). In addition, four mutations in gene S (three cases with the sI195M mutation and one with the W196L mutation), were detected, corresponding to a rate of 6% of vaccine escape mutations. Althougth the small sample size, an association was found between the occurrence of HBV resistance mutations and HBeAg positivity, co-infection with HIV and a history of treatment for HBV and/or HIV.