Failure to confirm specificity of samples containing a very high titer of hepatitis B surface antigen (HBsAg)

Two samples repeatedly positive for HBsAg by the AusRIA II screening procedure failed to be confirmed by neutralization with anti-HBs serum. Both samples could be effectively neutralized by the same anti-HBs sera if diluted 1:10, 1:50 and 1:100 prior to testing. It is suggested that the inability to neutralize was due to a very high concentration of HBsAg in these samples.