Presence of HBV S-gene mutants in immunocompromised patients.

Hepatitis B virus (HBV) is responsible for a serious, potentially fatal disease that affects approximately two billion people worldwide. Although an extended HBV immunization program has run since 1991, representing the most effective preventive measure possible, leading to a dramatic reduction of HBV hepatitis incidence, 4.5 million new HBV infections still occur every year. In 1988 the emergence of HBV S-gene mutants was first observed in Italian vaccinated children’s sera with the presence of both HBs antigen and anti-HBs antibodies. S-gene sequence revealed glycine (G) to arginine (A) substitution at position 145, within the a-determinant of S-gene, causing conformational changes that allow for the virus to escape the vaccine-induced response (Zanetti, 1988). Other similar mutations were later found in immunocompromised patients, responsible for HBV reactivation by immune escape in previously anti-HBs immune persons (Sheldon, 2008). As the prevalence of HBV surface antigen (HBsAg) variants is unknownwe investigated the presence of HBsAg mutations in 200 consecutive Ligurian patients, monitored for viral load and drug resistance. Virus sequences were obtained by the Trugene®