June 28, 2006
California Aggie
Grant Gives Wings to Sand Fly Study
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Researchers Claudio Meneses and Melody Malpass examine a container of sand flies. Meneses and Malpass study the protein components in sand fly saliva. (Media Credit: Joanna Tung) |
By Michael Steinwand
Aggie Science Editor
DAVIS--Imagine a fly three times smaller than a mosquito, with a similar thirst for blood, flying silently from animal to animal. Now imagine that insect passing on parasites that cause a fatal disease afflicting people in 88 countries around the world. For UC Davis medical entomologist Greg Lanzaro, this scenario is a reality that he and his research team are seeking to combat.
Recently awarded a research grant totaling $1.3 million from the National Institutes of Health, UC Davis researchers led by Lanzaro will examine the role of the saliva of these vampiric sand flies in transmitting the disease visceral leishmaniasis. VL is caused by the Leishmaniasis parasite, which attacks internal organs like the liver and spleen, and is fatal if untreated.
The study is the first ever on VL and the role of saliva during parasitic transmission.
"I think there's a general excitement among the campus, especially people in the area of global health," Lanzaro said. "We're really looking at things that have never been thought about before."
Blood-sucking insects such as mosquitoes and sand flies have been historically viewed as "flying syringes," simply passing disease from one organism to another while feeding. That view changed, however, when researchers discovered that the interaction between the insect and its pathogen is oftentimes more complex.
"What we're learning as time goes on is that the insect vector has more of a role, such as in the developmental stages of the pathogen," Lanzaro said. "You couldn't have a lot of transmission of diseases without the insect. The insect plays a central role."
There are approximately 20 species of Leishmania parasites that are infectious to humans and approximately 30 species of sand fly capable of transmitting them worldwide, according to the World Health Organization.
The grant, which funds the study through March of 2010, will enable the researchers to study several aspects of parasite-sand fly interaction. The results of the inquest may yield a vaccine to the disease, officials say.
The UC Davis study will examine the VL-causing parasite Leishmania chagasi during transmission from Brazilian and Costa Rican strains of the sand fly while feeding on hamsters. Researchers will analyze the pathology of the parasites after its time in the host fly, the time when it is suspected that the parasite has modified. Lanzaro said preliminary studies have shown that while the Brazilian species of fly transmits VL, the Costa Rican variety does not.
Another goal of the study is to examine the saliva of the sand fly, which contains compounds that prevent blood coagulation and the body's immune response. Lanzaro's team will focus on the protein maxadilan, which suppresses white blood cells that normally target and destroy parasites.
Researchers hope that exposing the test hamsters to a synthetic form of this protein will stimulate creation of antibodies for maxadilan, essentially protecting them against the immunosuppressant agent in the fly's saliva.
If successful, this method could serve as the basis for vaccination against parasitic disease, which Lanzaro said has never been done before.
"That would be something very, very novel," he said. "If we can come up with some way of treating this disease that's effective … we'll be doing people a good service."
