Scientists prepare an innovative vaccine against leishmaniasis

Universitat Autonoma De Barcelona researchers working in collaboration with the INIA (National Institute of Agricultural and Food Research and Technology) and Germans Trias i Pujol Hospital in Badalona, near Barcelona, are developing the first vaccine against leishmaniasis produced using insect larvae. The new vaccine is based on introducing specific genes and proteins from the protozoan Leishmania infantum into the patient. Although it is currently in the preliminary phase, scientists believe it could be much more effective than conventional vaccines.

Leishmaniasis is one of the biggest global health problems. In our part of the world, it is produced by the protozoan Leishmania infantum, and dogs are the main reservoir. The disease is spread through the bites of the phlebotomy, an insect similar to the mosquito. Clinical manifestations go from light skin lesions to visceral complications and even death. The disease affects more than 12 million people in the world, and 250 million more are at risk. Current treatments are not satisfactory, and although an effective vaccine would be the best way to confront the disease, conventional vaccines have failed.

UAB researchers working in collaboration with the INIA and Germans Trias i Pujol Hospital are working on the development of an unconventional vaccine that could be more effective in treating the disease. In an effort to make the vaccine as specific as possible, the researchers are conducting epidemiological tests on dogs and humans to find out whether the degree of the illness and the differences between regions, species (dog or humans) and infected individual persons are related to the presence of different antibodies against the infectious agent, the protozoan Leishmania infantum.

To create the vaccine and the reagents used in the epidemiological studies, the scientists have isolated the protozoan gene and inserted it into a virus that affects insects (baculovirus) and have infected the larvae of a small worm (Trichoplusia ni) with them. These larvae act as bioreactors and produce large quantities – and at a much lower cost than with conventional reactors involving microorganisms – of the proteins that are codified by these genes and are responsible for the production of antibodies in those affected. Each person would be administered a DNA vaccine with the genes that codify for the proteins of the protozoan that generates most antibodies in the geographical region. Later, the person would be vaccinated again, but this time directly with the proteins associated with the genes (produced cheaply in insect larvae). The aim is to increase effectiveness. The vaccines could be used as prevention or therapeutically.

“Selectivity for each individual and the combination of the vaccination with DNA and protein will probably make this new vaccine much more effective than current ones. Furthermore, the method of producing them in insect larvae would considerably reduce the costs,” explains Jordi Alberola, the main researcher for the project.

Science Daily
August 1, 2006

Original web page at Science Daily