HOST-CELL CYCLOPHILIN IS IMPORTANT FOR THE INTRACELLULAR REPLICATION OF LEISHMANIA-MAJOR

The antiparasitic effects of cyctosporin A were examined in leishmania l infection by analysing the role of CsA-binding proteins (cyclophilin s) in the host-parasite interaction. We hypothesized that the leishman icidal effects of CsA on Leishmania major infected macrophages might b e mediated through a cyctophilin of either the parasite or the host ce ll. Two cyclophilins (20 and 22 kDa) were purified from L. major paras ites and N-terminally sequenced. Although enzyme activity of these cyc lophilins was inhibited by CsA, pretreatment of L. major parasites wit h CsA did not result in reduction of a subsequent macrophage infection , arguing against a role of L. major cyclophilins as infectivity poten tiators. However, host-cell cyclophilin A (CypA) was found to be criti cally involved in the intracellular replication of L. major parasites in murine macrophages. An antisense oligonucleotide to murine CypA was constructed and added to cultures of peritoneal macrophages prior to infection with L. major parasites. This treatment strongly reduced the expression of CypA in macrophages and resulted in the inhibition of t he intracellular replication of L. major amastigotes. These data indic ate that interaction of amastigotes with host-cell cyclophilin is an i mportant part of the intracellular replication machinery of L. major a nd define, for the first time, a direct involvement of a cyclophilin i n the survival strategies of an intracellular parasite.