P2RX7 and infection: However, when P2X7 receptor gene knockout mice and parental C57BL/6J mice are infected intradermally with Leishmania major, no difference in resolution of lesions is observed, suggesting that, in the absence of P2X7 receptors, other anti-parasitic defence mechanisms compensate to control infection in vivo (C. Miller, A. Zakrzewski, M. Katrib, N. Smith, unpublished observations).