Contribution of quantitative viral markers to document hepatitis B virus compartmentalization in cerebrospinal fluid during hepatitis B with neuropathies

Extrahepatic manifestations linked to hepatitis B Virus (HBV) are usually indirect consequences of immune-mediated mechanisms triggered by the virus replication. Strong evidence of brain HBV replication is missing and direct involvement of HBV in nervous system symptoms has been rarely reported. We report two cases of neurological manifestations contemporary to HBV infection. In both cases, HBV-DNA and HBsAg could be quantified in the cerebrospinal fluid (CSF) at relatively high levels. Differential quantification of HBsAg and HBV viral load both in CSF and in blood as well as phylogenic studies on HBV genomic sequences obtained from blood and CSF provided strong arguments for central nervous system viral replication in both cases. Direct causality of HBV replication in the central nervous system in these clinical situations is certainly not demonstrated but these findings could expand the list of hepatitis viruses possibly involved in neurological disorders. Further studies should be promoted to better document possible HBV replication in the brain tissues and its consequences.