HBsAG positive reactivity in man not due to hepatitis B virus

A viral infection characterised by serum HBsAg positivity with serum anti-HBc negativity has been encountered in Senegal. The infection is not associated with the presence of HBeAg, so it differs from hepatitis B virus in its core antigen, but the surface antigen of the two viruses share some epitopes. After the loss of HBsAg, neither anti-HBc nor anti-HBs becomes detectable. Anti-HBs, naturally acquired or produced by immunisation, does not protect against this new infection. Chronic carriage occurs. If this new infection is confirmed to cause chronic liver disease, hepatitis B vaccine should include surface antigen from the new virus.