Targeting wild-type Erythrocyte receptors for Plasmodium falciparum and vivax Merozoites by Zinc Finger Nucleases In- silico: Towards a Genetic Vaccine against Malaria

Background Malaria causes immense human morbidity and mortality globally. The plasmodium species vivax and falciparum cause over 75 % clinical malaria cases. Until now, gene-based strategies against malaria have only been applied to plasmodium species and their mosquito-vector. Merozoites of these two respective plasmodium species target and invade red blood cells (RBCs) by using the duffy antigen receptor for chemokines (DARC), and Sialic Acid (SLC4A1) residues of the O-linked glycans of Glycophorin A. RBCs of naturally selected duffy-negative blacks are resistant to P.vivax tropism. We hypothesized that artificial aberration of the host-pathway by target mutagenesis of either RBC –receptors, may abolish or reduce susceptibility of the host to malaria. As a first step towards the experimental actualization of these concepts, we aimed to identify zinc finger arrays (ZFAs) for constructing ZFNs that target genes of either wild-type host-RBC- receptors. Methods In-Silico Gene & Genome Informatics Results Using the genomic contextual nucleotide-sequences of homo-sapiens darc and glycophorin-a, and the ZFN-consortia software- CoDA-ZiFiT-ZFA and CoDA-ZiFiT-ZFN: we identified 163 and over 1,000 single zinc finger arrays (sZFAs) that bind sequences within the genes for the two respective RBC-receptors. Second, 2 and 18 paired zinc finger arrays (pZFAs) that are precursors for zinc finger nucleases (ZFNs) capable of cleaving the genes for darc and glycophorin-a were respectively assembled. Third, a mega-BLAST evaluation of the genome-wide cleavage specificity of this set of ZFNs was done, revealing alternate homologous nucleotide targets in the human genome other than darc or glycophorin A. Conclusions ZFNs engineered with these ZFA-precursors--with further optimization to enhance their specificity to only darc and glycophorin-a, could be used in constructing an experimental gene-based-malaria vaccine. Alternatively, meganucleases and transcription activator-like (TAL) nucleases that target conserved stretches of darc and glycophorin-a DNA may serve the purpose of abrogating invasion of RBCs by falciparam and vivax plasmodia species.