Component Of Fly Saliva Has Promise For Vaccine.(Brief Article)

2001 AUG 22 - (NewsRx.com & NewsRx.net) --

Researchers seeking to make a vaccine against a serious parasitic infection have discovered a dose of fly saliva might be just what the doctor ordered.

Leishmaniasis, a disabling and sometimes deadly tropical illness, is caused by a parasite transmitted to people through the bite of a sand fly. Scientists from the U.S. National Institute of Allergy and Infectious Diseases (NIAID) now describe how a vaccine they developed against a component of sand fly saliva prevents leishmaniasis in mice.

Leishmaniasis, a major health problem in many tropical and desert climates, has resisted efforts to develop an effective vaccine. "[This] report describes a novel vaccine," says NIAID director Anthony S. Fauci, MD. "Rather than targeting the parasite, as is typical, our researchers produced a vaccine to the saliva of the insect that transmits the parasite. This approach could potentially be used to develop vaccines for other insect- or tick-borne diseases."

Leishmaniasis refers to a group of related diseases. Different species of the single-celled parasite Leishmania can cause flesh-eating nose, throat, and mouth infections (mucosal leishmaniasis); painful skin lesions (cutaneous leishmaniasis); or fatal infestations of the internal organs (visceral leishmaniasis). An estimated 12 million people currently are affected by one or more of these diseases, most of whom live in South or Central America, Africa, and the Middle East.

NIAID's Jose Ribeiro, MD, PhD, an expert on the biochemistry of blood-feeding bugs, has spent more than 30 years studying how components of saliva not only help insects and ticks obtain their blood meals but also modulate the immune response. He and others have previously shown that laboratory animals immunized with sand fly saliva often resist infection when later bitten by a Leishmania-carrying insect, or challenged with parasites in the presence of sand fly saliva.

In the new study reported in the August 6, 2001, in the Journal of Experimental Medicine, Ribeiro directed a research team that sought to use this information to produce a novel vaccine against the disease. Jesus Valenzuela, PhD, Ribeiro, and their colleagues examined saliva from the sand fly carrier of L. major, a parasite species that causes cutaneous leishmaniasis. The researchers separated the proteins of the saliva ...