The pir gene family: chronic infection, immunity and virulence

Multigene families are present on most of the chromosomes of the malaria parasite Plasmodium. One gene family, pir (Plasmodium interspersed repeat), is present in all Plasmodium genomes sequenced so far. Despite their discovery more than ten years ago, the function of pir genes is not understood. Recent results from Dr Langhorne's laboratory suggest that they may be virulence factors. Dr Langhorne plans to use a well-defined animal model to discover the interactions of pirs with the mammalian host, which could explain their role in virulence or in other host-parasite interactions. An investigation of the biology of this gene family and its interactions with the host may be key to understanding malaria pathogenesis, and could change our ideas about the relationship between the immune response and virulence. The knowledge gained will promote new research directions and aid new approaches to intervention.