Assembly and expression of a synthetic gene encoding the antigen Pfs48/45 of the human malaria parasite Plasmodium falciparum in yeast

Pfs48/45 is an important transmission-blocking vaccine candidate antigen of the human malaria parasite Plasmodium falciparum. This study was aimed at synthesis of recombinant Pfs48/45 containing conformation-constrained epito pes of the native antigen in yeast. Since in the yeast Saccharomyces cerevi siae induction of gene-expression led to prematurely terminated transcripts , an entirely synthetic gene of higher GC content was assembled. Replacemen t of the AT rich natural gene by the synthetic gene relieved the observed p remature transcription termination. Nevertheless, recombinant protein expre ssion could not be detected. In contrast, in the yeast Pichia pastoris low levels of recombinant Pfs48/45 were produced upon induction of synthetic ge ne expression. The recombinant protein was shown to be disulphide-bridge co nstrained, but was not recognised by transmission-blocking antibodies and d id not induce transmission-blocking sera in mice. (C) 2000 Elsevier Science Ltd. All rights reserved.