The invention provides an antibody or antigen binding fragment thereof capable of binding to the antigen binding pocket of the AP33 antibody, wherein said antibody or antigen binding fragment thereof comprises VL CDR1 (L1), VL CDR2 (L2), and VL CDR3 (L3) consisting of the amino acid sequences of SEQ ID NO:1, SEQ ID NO:2 and SEQ ID NO:23 respectively, and comprises VH CDR1 (H1), VH CDR2 (H2), and VH CDR3 (H3) consisting of the amino acid sequences of SEQ ID NO:24, SEQ ID NO:25, and SEQ ID NO:26 respectively. The invention also provides compositions, methods, nucleic acids and uses.