Recombinant VAR2CSA DBL3-X constructs from 29 genotypically distinct P. falciparum isolates were produced in Baculovirus-infected insect cells and tested in ELISA essentially as described above. The three-dimensional structure of the 3D7-VAR2CSA DBL3-X sequence (PFL0030c, amino acids 1217-1559) was modelled in silico as described elsewhere . Briefly, the crystal structure of EBA-175 F1 (PDB code 1ZRO chain A) (Tolia et al., 2005) , which has 28% sequence identity to the 3D7-VAR2CSA DBL3-X domain, was used as a template. The model was evaluated with respect to locations of conserved cysteine bridges and buried hydrophobic residues in the structures of DBL domains from EBA-175 F1 and F2 (Tolia et al., 2005) and Pk-a DBL (Singh et al., 2005) .