Peptides of the liver stage antigen-1 (LSA-1) of Plasmodium falciparum bind to human hepatocytes

Synthetic peptides from the liver stage antigen-1 (LSA-1) antigen sequence were used in HepG2 cell and erythrocyte binding assays to identify regions that could be involved in parasite invasion. LSA-1 protein peptides 20630 (²¹INGKIIKNSEKDEIIKSNLRY⁴⁰), 20637 (¹⁵⁷KEKLQGQQSDSEQERRAY¹⁷³), 20638 (¹⁷⁴KEKLQEQQSDLEQERLAY¹⁹⁰) and 20639 (¹⁹¹KEKLQEQQSDLEQERRAY²⁰⁷) had high binding activity in HepG2 assays. Were located in immunogenic regions; peptide cell binding was saturable. Peptide 20630 bound specifically to 48kDa HepG2 membrane surface protein. LSA-1 peptides 20630 (²¹INGKIIKNSEKDEIIKSNLRY⁴⁰) and 20633 (⁸¹DKELTMSNVKNVSQTNFKSLY¹⁰⁰) showed specific erythrocyte binding activity and inhibited merozoite invasion of erythrocytes in vitro. A monkey serum prepared against LSA-1 20630 peptide analog (CGINGKNIKNAEKPMIIKSNLRGC) inhibited merozoite invasion in vitro. The data suggest LSA-1 "High Activity Binding Peptides" could play a possible role in hepatic cell invasion as well as merozoite invasion of erythrocytes.