The present invention relates to a binding molecule comprising at least three binding specificities, wherein (a) the first specificity is for a Hepatitis B virus (HBV) surface antigen selected from HBV small surface antigen, HBV medium surface antigen and HBV large surface antigen; (b) (i) the second and third specificity are for CD3 and CD28, respectively; or (ii) the second and third specificity are selected from specificities for CD16, CD56, NKp30, NKp46, 4-1BB and NKG2D; and (c) each binding specificity is provided by one or more binding sites, each binding site being independently provided by (i) a set of six complementarity determining regions (CDRs), wherein said set of six CDRs consists of a first set of three CDRs and a second set of three CDRs, wherein said first and said second set is each comprised in an immunoglobulin domain; or (ii) a set of three CDRs, wherein said set of three CDRs is comprised in an immunoglobulin domain.