Baqiyatallah University of Medical Sciences, Baqiyatallah Research Centre for Gastroenterology and Liver Disease, Tehran, Iran.
A wide variety of commercial assays is available for the detection of HBsAg. Clearly, the sensitivity of an assay to detect a variant is dependent on the anti-HBs used. Thus, it is not surprising that there are examples of variants that cannot be detected by all assays. Accumulating data from Europe, Asia and Africa about HBsAg variants which are not recognized by either monoclonal or polyclonal antibodies specific for wild-type group 'a' determinant, but positive by DNA PCR in chronic patients and from vaccinated children are increasing. This would impose a challenge for public health issues of hepatitis B virus. In this review we tried to summarize the discrepancies between results of HBsAg assays and to explain some rationales for these inconsistencies.