Down-regulation of gp63 in Leishmania amazonensis reduces its early development in Lutzomyia longipalpis

The zinc protease (gp63) of promastigotes was found to play a role in the sand fly part of the Leishmania life cycle. Lutzomyia longipalpis females were fed with promastigotes (10(6) per ml) of a Leishmania amazonensis clone whose gp63 was up- and down-regulated by directional cloning into P6.5 for sense- and anti-sense transcription. Early development was found to differ significantly between the sense- and anti-sense transfectants 2 days post-feeding. The sense transfectants overexpressing gp63 were found similar to those with the vector alone: both developed in the gut at high rates of approximately 90-100% and at a high density with moderate to heavy parasite loads in >70% of the infected females. In contrast, the anti-sense transfectants with gp63 down-regulated developed at a lower rate (approximately 70%) and, significantly, at a very low density, with moderate to heavy parasite loads only in approximately 30% of the infected females. On day 9 post-feeding, all three groups of transfectants developed at a similar rate of approximately 50% with comparable parasite loads. Thus, gp63 plays a role at the early stage of L. amazonensis establishment in L. longipalpis.