Malaria is one of the most deadly diseases in the world, with more people killed from this infectious disease annually except for AIDS and tuberculosis. An estimated 400 million people are infected with malaria every year leading to 1-3 million deaths. The United States and Western countries have eliminated the disease but it persists in Central and South America, Africa, and Asia. Resistance to antimalaria drugs has spread rapidly across the globe and the most common drug, chloroquine, is no longer effective in most of the endemic areas.

Recently, another mosquito-borne disease, the West Nile virus, has emerged as a serious health threat in the United States. It was first isolated from the blood of a woman in the West Nile district of Uganda in 1937 and recognized as a cause of severe human disease during an outbreak in Israel in 1957. In 1999, there was a deadly outbreak in New York city and the virus has now spread throughout most of the country. Infection with the virus can lead to fatal encephalitis (inflammation of the brain) in humans and horses and mortality in birds. This virus is carried by infected mosquitoes, primarily members of the Culex species. Human vaccines are currently at the development stage and a vaccine for horses has been approved but the effectiveness remains to be evaluated. The threat of the West Nile virus has increased due to an apparent infection being transmitted though the blood supply.

The best current approach towards eliminating these diseases is to attack and eradicate the carriers. Chemical pesticides such as DTT continue to be used but the broadness of their targeting and secondary ecological effects have made their application undesirable. In addition, mosquitoes that are resistant to pesticides continue to emerge. A variety of naturally occurring predators, parasites, and pathogens of vector insects exist, including Bacillus sphaericus. The usefulness of the insecticidal protein produced by B. sphaericus is limited by the lack of structural information about these proteins. Therefore, we are determining the structure of this protein. Crystals have been obtained and the determination of the structure is underway.

Related Papers
C.-K. Chiou, E. W. Davidson, T. Thanabalu, A. G. Porter, and J. P. Allen (1999) “Crystallization and preliminary X-ray diffraction studies of the 51 kDa protein of the mosquito-larvicidal binary toxin from Bacillus sphaericus” Acta Crystallographica D55, 1083-1085.