A HBS-specific antibody, a LHBS-specific antibody, a WT LHBS-specific antibody, an immunoassay kit comprising the antibodies, and a method of detecting pre-S2 deletion mutant LHBS using the immunoassay kit are disclosed herein. The method comprises incubating a biological sample with a first antibody to captured HBS proteins; detecting the LHBS and WT LHBS bound to the immobilized first antibody, respectively; and calculating the amount of the pre-S2 deletion mutant LHBS protein by subtracting the amount of the WT LHBS protein from that of the LHBS protein. Advantageously, by the method described herein, the amount of the pre-S2 deletion mutant LHBS, a potential high-risk marker for HCC incidence in chronic HBV carriers and recurrence in HCC patients after hepatectomy surgery, in a biological sample may be easily calculated without mutual influence between the WT and pre-S mutant LHBS while reducing the labor-intensive process for cloning each gene product before analysis.
