All P. falciparum parasites used in this study were grown in 0 + erythrocytes (Cranmer et al., 1997) . 3D7, FCR3 and NF54 are long-term in vitro cultured lines. All expressed non-PAM-type VSA, meaning that intact IEs were recognized to a similar extent by IgG in the plasma of P. falciparum-exposed men and sympatric, multigravid women in a flow cytometry assay of VSA expression (Fig. 1 , 3D7-SM) . The 3D7 subline 3D7-SM was derived by human plasma antibody selection of 3D7 for expression of non-PAM-type PfEMP1 associated with severe malaria in children as described Jensen et al., 2004) . The VSAPAM-expressing subline 3D7-BeWo was selected by repeated panning of IEs on the choriocarcinoma line BeWo as described elsewhere (Haase et al., 2006) . Parasites were considered as expressing VSAPAM if the level of labelling of intact IEs by IgG in a panel of plasma samples from P. falciparum-exposed multigravid women was significantly higher than the level in plasma from sympatric men (Fig. 1, FCR3 -CSA and NF54-VAR2CSA). The characteristics of the plasma IgG recognition pattern of VSAPAM and non-PAM-type VSA have been documented in detail elsewhere (Ricke et al., 2000; Staalsoe et al., 2001) . Sublines of FCR3 and NF54 (FCR3-CSA and NF54-CSA respectively) were selected for expression of VSAPAM by repeated panning of IEs on CSA in vitro (Fried and Duffy, 1996; Ricke et al., 2000) . NF54-CSA was further selected for IE reactivity with rabbit antiserum specific for VAR2CSA DBL5-e, resulting in subline NF54-VAR2CSA (Salanti et al., 2004) . Additional sublines of FCR3 (FCR3-A745 and FCR3-CD36) expressing non-PAM VSA were selected by repeated panning on CSA-negative CHO cells (CHO-A745) and recombinant CD36, respectively, essentially as described for BeWo and CSA selection. Isolates EJ24 and EJ27 were obtained from the peripheral blood of pregnant, P. falciparum-exposed women and adapted to in vitro culture . Both isolates were selected for expression of VSA reacting with the human VSAPAMspecific monoclonal antibody PAM1.4 (see below), essentially as described , but using Protein A-coated magnetic microbeads, as VSAPAM-expressing IEs are prone to non-specific labelling by second-step antisera (Creasey et al., 2003; Rasti et al., 2006) .