We have evaluated a technology called transcriptionally active PCR (TAP) for 
high throughput identification and prioritization of novel target antigens from 
genomic sequence data using the Plasmodium parasite, the causative agent of 
malaria, as a model. First, we adapted the TAP technology for the highly AT-rich 
Plasmodium genome, using well-characterized P. falciparum and P. yoelii antigens 
and a small panel of uncharacterized open reading frames from the P. falciparum 
genome sequence database. We demonstrated that TAP fragments encoding six 
well-characterized P. falciparum antigens and five well-characterized P. yoelii 
antigens could be amplified in an equivalent manner from both plasmid DNA and 
genomic DNA templates, and that uncharacterized open reading frames could also 
be amplified from genomic DNA template. Second, we showed that the in vitro 
expression of the TAP fragments was equivalent or superior to that of 
supercoiled plasmid DNA encoding the same antigen. Third, we evaluated the in 
vivo immunogenicity of TAP fragments encoding a subset of the model P. 
falciparum and P. yoelii antigens. We found that antigen-specific antibody and 
cellular immune responses induced by the TAP fragments in mice were equivalent 
or superior to those induced by the corresponding plasmid DNA vaccines. Finally, 
we developed and demonstrated proof-of-principle for an in vitro humoral 
immunoscreening assay for down-selection of novel target antigens. These data 
support the potential of a TAP approach for rapid high throughput functional 
screening and identification of potential candidate vaccine antigens from 
genomic sequence data.