This invention is directed to transition-state analog compounds and to the use of said compounds as inhibitors of nucleoside hydrolase and transferase enzyme activity of parasites. This invention is further directed to the use of said compounds to treat infections and diseases caused by certain bacterial and plant toxins. -GOVT PAC STATEMENT OF GOVERNMENT INTEREST PAR This invention was made with government support under NIH Grant No. GM41916. The government has certain rights in this invention.

The present invention relates to the use of an inhibitor of CTP synthetase, such as a glutamine analogue, and a substance capable of suppressing toxic effects thereof in vivo, in the manufacture of a medicament for the treatment of a disease caused by a parasitic protozoa. More specifically, said substance capable of suppressing toxic effects may be a nucleobase, such as a purine base or a nucleoside, while the glutamine analogue advantageously is 6-diazo-5-oxo-L-norleucine (DON). The invention also relates to a pharmaceutical composition as such for the treatment and/or prevention of a disease caused by a parasitic protozoa, wherein the disease is selected from the group consisting of malaria, leishmaniasis and trypanosomiasis, e.g. American trypanosomiasis (Chaga's disease), or African trypanosomiasis (African sleeping sickness).

The present invention relates to the intersection of the fields of immunology and protein engineering, and particularly to antigens and vaccines useful in prevention of infection by Trypanosoma protozoa. Provided are recombinant protein antigens, compositions, and methods for the production and use of such antigens and vaccine compositions.

A process for inhibiting a mammalian cancerous cell or virally infected cell includes providing a Trichomonas vaginalis purine nucleoside phosphorylase enzyme or a tail mutant purine nucleoside phosphorylase enzyme in proximity to the mammalian cancerous cell or the virally infected cell and exposing the enzyme to a purine nucleoside phosphorylase enzyme cleavable substrate to yield a cytotoxic purine analog. The process includes introducing to the cell a vector containing the phosphorylase enzyme, or a DNA sequence coding for the same and delivering to the cell an effective amount of the substrate such as 9-(β-D-arabinofuranosyl)-2-fluoroadenine (F-araA).

The present invention is directed to purine nucleoside analogs of the general Formula (I), or tautomers thereof, physiologically acceptable salts, solvents and physiologically functional derivatives thereof, and pharmaceutical compositions comprising such compounds, salts and derivatives, which are useful as anti-bacterial and anti-protozoan agents. The invention is also directed to methods for treating a bacterial or protozoan infection in a mammal and use of the compounds for inhibiting the growth of a bacteria or protozoa.