Development of a fundamentally new "candidate," or potential, vaccine for visceral leishmaniasis (LEASH-ma-NIGH-a-sis), a parasitic disease that kills about 60,000 people annually, is reported in the current issue of ACS Chemical Biology. Spread by the bite of infected female sand flies, visceral leishmaniasis infects about 500,000 people annually, with the majority of cases occurring in India, Bangladesh, Nepal, Sudan and Brazil.
Despite a major research thrust by the World Health Organization (WHO), no effective vaccine exists for the visceral, or internal, form of leishmaniasis. A milder form of leishmaniasis, which infects the skin, was reported among American military personnel during Operation Desert Storm and other conflicts in the region.
Peter H. Seeberger, Ph.D., of the Laboratory for Organic Chemistry at the Swiss Federal Institute of Technology (ETH) in Zurich headed the research group. It also included researchers from the Swiss Tropical Institute in Basel and Pevion Inc., a biotech company focusing on virosomal delivery systems. The group reported their findings in ACS Chemical Biology, one of 34 peer-reviewed journals published by the American Chemical Society, the worlds largest scientific society.
Several leishmaniasis candidate vaccines are in various stages of development. Seebergers group, however, reported development of a unique two-part preparation. It is among a new genre of carbohydrate-based vaccines stirring excitement in medical circles. Carbohydrates are chemical compounds that include sugar and are made from units linked together like beads on a chain.
"This is the first and only carbohydrate vaccine candidate against this disease," Seeberger stated. "This candidate vaccine brings something new to the table and may be of use not only in humans but also for pet vaccines. Dogs get leishmaniasis, particularly in Southern Europe and a vaccine is urgently needed there, as well."
Carbohydrate vaccines already are used in everyday medicine, including vaccines to immunize against meningitis and other bacterial infections, mainly in small children in the United States. Those vaccines use carbohydrates isolated from the actual bacteria responsible for the diseases. The carbohydrates act as antigens, which stimulate the immune system to deploy a protective shield against disease.
"Right now there is a major push to utilize synthetic carbohydrates as antigens in order to control the purity and composition and avoid possible contamination," Seeberger explained. His own group, together with a biotech company - Ancora Pharmaceuticals in Medford, Mass. is working on one such malaria vaccine that is in late-stage preclinical trials. Other candidate vaccines against anthrax and tuberculosis are at an earlier stage of development.