USE OF PCR IN RESOLVING DIAGNOSTIC DIFFICULTIES POTENTIALLY CAUSED BYGENETIC-VARIATION OF HEPATITIS-B VIRUS

Aims-To assess the relevance of genetic variants of hepatitis B virus (HBV) and to demonstrate the usefulness of the polymerase chain reacti on (FCR) in cases of HBV diagnostic difficulty. Methods-Five serum sam ples from patients that presented diagnostic difficulty in routine lab oratories were sent to a research laboratory for PCR, and if appropria te, S gene sequencing, in vitro expression, and antigenic analysis. Re sults-The demonstration of HBV in serum by PCR allowed a definitive di agnosis of current infection. One serum sample with poor reactivity in a diagnostic assay had a minor hepatitis B surface antigen (HBsAg) va riant and another with very poor reactivity had multiple variants of H BsAg. Transient HBsAg reactivity was observed in a recently vaccinated patient. A hepatitis Be antigen (HBeAg) false positive reaction was n oted in a patient from a well defined risk group for HBV. One patient who was strongly HBsAg/HBeAg positive, but anti-hepatitis B core antib ody negative, was viraemic. Conclusions-PCR may become the gold standa rd for the diagnosis of current HBV infection. HBV variants are respon sible for a proportion of diagnostically difficult cases. Modification of commercial assays is necessary to increase the sensitivity of dete ction of such variants.