cggaattcGATACAAATGGTGCCTGT and 3′: CATTTCTTT TCATTCTTACCATTATTAGTGCA to generate the 3D7specific, and 5′: AAGAATGAAAAGAAATGTATTAATTC and 3′: atttgcggccgcATATACTGCTATAATCTCC to generate the FCR3-specific part of the chimera. These primers amplify a slightly smaller PCR product than the original primers used for making the FCR3 and 3D7 DBL3-X constructs, and this is reflected in the smaller molecular size of the chimeric construct. The two PCR products were gel-purified and used in a second PCR using the two outer primers to generate a PCR product consisting of 5′ 3D7 and 3′ FCR3, with an EcoRI site and a NotI site. The PCR product was cloned into a modified pAcGP67-A vector (BD Biosciences) and expressed in insect cells as described (Salanti et al., 2004) .