Fly spit protein holds back parasite infection in monkeys

A protein found in sand fly spit hints at hope for creating a vaccine to combat leishmaniasis, a deadly parasitic scourge spread by sand flies.

Monkeys given a shot containing the protein PdSP15 had smaller skin sores and fewer Leishmania parasites circulating in their blood after infection than monkeys that received a shot without the protein. Blood taken from humans who had been bitten by sand flies not infected with Leishmania parasites produced a high level of antibodies in response to the protein, showing that PdSP15 itself spurs an immune response. The results, which appear June 3 in Science Translational Medicine, support earlier studies pointing to proteins in sand fly saliva as valuable components for developing a vaccine for leishmaniasis.