Analysis of monoclonal antibodies directed against sporozoites of Plasmodium falciparum

Mouse monoclonal antibodies (one lgG2 and three IgG1) were prepared against the circumsporozoite antigen of Plasmodium falciparum. Comparisons of epitope recognition and binding site affinity of the monoclonal antibodies were then made against different portions of the circumsporozoite antigen. The binding site of two of these monoclonal antibodies, obtained from the Walter Reed Army Institute of Research, were different from the binding sites of the two monoclonal antibodies prepared at the Naval Medical Research Institute, based on competitive binding assays. The latter two, NFS1 and NFS2, were similar in that both reacted with (NANP-NVDP-NANP), although the NFS2 failed to react with this peptide at the higher dilutions. Furthermore, NFS1 strongly inhibited the binding of NFS2 to R32tet32, a large peptide containing the (NANP-NVDP-NANP) epitope, whereas the reverse inhibition did not take place suggesting that NFS1 has a greater affinity for this peptide.