Defense Mechanism Found In Infected Ticks May Protect Against Harmful Parasite

Babesiosis is a well-recognized disease worldwide and recently gained increased attention as an emerging zoonosis. Transmitted to animals and humans by ticks infected with the Bebesia sp. parasite, symptoms may include fever, fatigue and hemolytic anemia. Antimcrobial peptides are defensive molecules found in the innate immune system of animals. Less toxic and more effective against multi-drug resistant bacteria, they are showing promise as a better choice for treatment of some bacterial and fungal infectious diseases.

In the study researchers identified a novel parasiticidal peptide named longicin from the tick species Haemaphysalis longicornis and tested its ability to inhibit infection. It showed a remarkable ability to inhibit the blood stage of equine Babesia equi by killing the parasites and resulted in reduction of parasitemia in animals with the zoonotic and murine Babesia microti. RNA analysis also demonstrated that longicin is capable of killing the canine strain, Babesia gibsoni.

“Here we report a defensin peptide, longicin, from the tick H. longicornis that exerts a babesiacidal effect,” say the researchers. “Theoretically, longicin may serve as a model for the development of chemotherapeutic compounds against tick-borne disease organisms.”

Reference: N. Tsuji, B. Battsetseg, D. Boldbaatar, T. Miyoshi, X. Xuan, J.H. Oliver, Jr., K. Fujisaki. 2007. Babesial vector tick defensin against Babesia sp. Parasites. Infection and Immunity, 75. 7: 3633-3640