PfRH2b

PfRH2b, short for reticulocyte binding-like protein homolog 2b, is a protein encoded by Plasmodium falciparum and a member of the PfRH family of merozoite invasion ligands. PfRH2b is a paralog of PfRH2a and is part of a group of surface proteins implicated in the recognition and engagement of erythrocytes during merozoite invasion. Like other PfRH genes, its expression and sequence show variation across parasite strains and life cycle stages.

Functionally, PfRH2b is believed to participate in erythrocyte invasion by contributing to receptor engagement on the red blood cell surface. It is associated with alternative invasion pathways that can supplement or compensate for other invasion ligands when primary routes are blocked or less active. The exact receptor interactions and the extent of its role relative to other PfRH family members can differ among parasite lines.

Structurally, PfRH2b is predicted to encode a type I membrane protein with a signal peptide, a sizable extracellular region containing reticulocyte binding–like motifs, a transmembrane domain, and a cytoplasmic tail. This organization supports its localization on the merozoite surface and its participation in the invasion process, where ligand-receptor interactions trigger downstream steps of merozoite entry.

Genetically and immunologically, PfRH2b exhibits polymorphism across isolates, reflecting ongoing adaptation to host receptors. Antibodies targeting PfRH family proteins can, in some contexts, inhibit invasion, underscoring the potential of PfRH2b as part of a multi-target vaccine strategy alongside other invasion ligands such as PfRH5. However, PfRH2b remains less characterized than PfRH5, with details of its essentiality and receptor specificity varying by parasite strain.

See also: PfRH family, PfRH5, erythrocyte invasion, merozoite surface proteins.