Var genes are restricted to the Laveranian subgenus of Plasmodium, which infects great apes and includes the human-infecting P. falciparum species [5], but other Plasmodium species encode other gene families that may have similar roles, including the sicavar family in the macaque parasite P. knowlesi [6, 7] and the pir family which appears widely in many species from rodent to human malarias [8, 9] (Fig. 1). Here, PIR is linked to malaria.