Sexually transmitted infection with an immune‐escape mutant hepatitis B virus (HBV) in an HBV‐vaccinated individual with acute HIV‐HCV infection

Immune pressure exerted on HBV by anti‐HBV antibodies and long‐term therapy with drugs that mutagenize the viral polymerase gene can select for mutations in its surface gene, leading to vaccine escape and evasion from serological detection. In general, these mutations are considered to be poorly transmissible. However, cases of HBV infection with vaccine‐escape mutant viruses have been reported in vaccinated individuals, mainly from high‐prevalence regions of the world. The possibility of an infection with HBV despite an effective vaccination may pose a major health issue, requiring a change in routine diagnostic and screening programmes. Here, we report a case of a HBV vaccine escape mutant infection in an effectively vaccinated individual. The patient was a 27‐year old man who has sex with men (MSM) who presented in September 2011 for the first time in a Berlin outpatient HIV clinic due to a newly diagnosed HIV infection. He was aware of several sexual high‐risk contacts within the past, but had a negative HIV and HCV antibody test (ELISA) in April 2011. He complained about slight fever, swollen cervical and axillary lymph nodes and general muscle pain. The Western blot confirmed an HIV infection. The HIV viral load was 24,000 copies/mL, the CD4 count was 550/mm 3 . His ALT levels were elevated to 10×the upper limit of normal (ULN) and he was additionally found to have acute HCV infection: The HCV viral load was 2 million IU/mL, the HCV genotype was 2c. Furthermore, he was anti‐HBc negative, HBsAG negative, and his anti‐HBs level was 121 IU/L. He reported to have been vaccinated for HBV in the past. Three months later, the patient was routinely retested. At this time point, his HBsAg turned out to be positive and anti‐HBs antibodies had vanished. His HBV viral load was 600 million IU/mL, and ALT had decreased to 2×ULN. Population sequencing revealed a genotype F and a S143L mutation in the surface gene consistent with a vaccine escape mutant HBV. A retrospective analysis of the initial blood sample showed a HBV DNA of 90 IU/mL. Conclusion To our knowledge, this is the first report of a sexually transmitted HBV virus with vaccine‐escape mutation in a vaccinated individual. Despite a fairly high CD4 count, the transmission may have been promoted by a loss of immunity through an acute HIV infection. Clinicians need to be aware of the possibility of HBV infections with mutant viruses.