ABSTRACT
The development of a vaccine for the prevention of primary cytomegalovirus (CMV) infection is a major public health priority. Live attenuated virus, recombinant viral vector, recombinant protein and peptide vaccines have been studied as potential vaccine candidates. In recent years, DNA vaccination strategies have been developed for many pathogens, including CMV. This review aims to bring together many aspects of this relatively new vaccine technology as applied to current research into the development of vaccines against CMV.
Subject(s)
Cytomegalovirus Infections/immunology , Cytomegalovirus Infections/prevention & control , Cytomegalovirus/immunology , Viral Vaccines/immunology , Animals , Antigens, Viral/genetics , Antigens, Viral/immunology , Cytomegalovirus/genetics , Genes, Viral , Humans , Viral Vaccines/geneticsABSTRACT
The American trypanosome Trypanosoma cruzi is exposed to toxic oxygen metabolites that are generated by drug metabolism and immune responses in addition to those produced by endogenous processes. However, much remains to be resolved about the parasite oxidative defense system, including the mechanism(s) of peroxide reduction. Here we show that reduction of peroxides in T. cruzi is catalyzed by two distinct trypanothione-dependent enzymes. These were localized to the cytosol and mitochondrion. Both are members of the peroxiredoxin family of antioxidant proteins and are characterized by the presence of two conserved domains containing redox active cysteines. The role of these proteins in protecting T. cruzi from peroxide-mediated damage was demonstrated following overexpression of enzyme activity. The parasite-specific features of T. cruzi cytoplasmic peroxiredoxin and T. cruzi mitochondrial peroxiredoxin may be exploitable in terms of drug development.
Subject(s)
Cytosol/enzymology , Glutathione/analogs & derivatives , Mitochondria/enzymology , Peroxidases/isolation & purification , Spermidine/analogs & derivatives , Trypanosoma cruzi/enzymology , Amino Acid Sequence , Animals , Cell Compartmentation , Dimerization , Drug Resistance , Genes, Protozoan , Glutathione/metabolism , Hydrogen Peroxide/metabolism , Hydrogen Peroxide/toxicity , Molecular Sequence Data , Peroxidases/genetics , Peroxidases/metabolism , Protein Structure, Quaternary , Sequence Homology, Amino Acid , Spermidine/metabolismABSTRACT
The parasitic protozoan Trypanosoma cruzi is exposed to toxic oxygen metabolites which arise from drug metabolism or immune mechanisms, in addition to those produced by endogenous processes. Identification and functional analysis of parasite enzymes which confer protection against oxidative stress is therefore of importance. To investigate the role of T. cruzi superoxide dismutase (SOD) we transfected epimastigotes with an expression vector containing a putative Fe-SOD gene homologue and achieved overexpression of enzyme activity (5-8 fold). Inhibition studies carried out on the partially purified enzyme revealed azide and H2O2 sensitivity and cyanide insensitivity, the profile expected of an Fe-isoform. Phenotypic analysis of transformed parasites showed that they were more susceptible than control cells to growth inhibition by the trypanocidal drug benznidazole and by gentian violet, an agent which can be used to decontaminate blood supplies in endemic areas. These results may reflect an imbalance in the antioxidant defences of the parasite produced as a result of overexpression of Fe-SOD.
