中文摘要：

典型的慢性HBV感染血清学特征是存在HBsAg，而抗-HBs阴性，但近年来有关nSsAs和抗-HBs双阳性的慢性HBV感染的报道越来越多，其具体发生机制仍有争论，故本文就其可能的相关机制作以下综述。

英文摘要：

The typical serological feature of chronic HBV infection is the presence of circ~ating HBsAg in pa- tients and lack of anti-HBs. However, the co-existence of HBsAg and anti-HBs in patients with chronic HBV infection has been reported more and more. So far, the mechanism underlying the presence of both HBsAg and anti-HBs remains un- known. This review focuses on the possible mechanisms leading to this phenomenon.