[Occult HBV infection in patients with anti-HBc positive alone].

OBJECTIVE

This study was designed to explore the incidence rate of occult HBV infection in patients with anti-HBc positive alone and analyze the possible reasons of occult infection.

METHODS

Sera of 183 patients carrying anti-HBc alone(A < or = 0.1) were collected and real-time PCR was used to select samples with HBV DNA positive. HBV pre-S/S amplification products were obtained by PCR, and clonal sequencing were then used for these samples with HBV DNA positive.

RESULTS

DNA quantitative results of three samples were greater than 10(3) copies/ml in 183 samples, with a fraction of 1.6%. Pre-S/S sequencing results of two samples from these three samples were obtained. Point mutations within "a" determinant with Q129R/P mutations and co-existence of the mutant type and wild type were found in the two samples.

CONCLUSIONS

Occult HBV infection existed in samples with anti-HBc alone. Factors contributing to the loss of HBsAg detection by immunoassays include S gene mutations and low levels of circulating antigen which are below the assay limit of detection. Occult HBV infection not only can lead to a false clinical diagnosis, but also can result in hematological pollution due to such occult infection of blood donors.