From 2002 to 2003, a global pandemic of severe acute respiratory syndrome (SARS) spread to 5 continents and caused 8000 respiratory infections and 800 deaths. To ameliorate the effects of future outbreaks as well as to prepare for biodefense, a process for the production of a recombinant protein vaccine candidate is under development. Previously, we reported the 5 L scale expression and purification of a promising recombinant SARS vaccine candidate, RBD219-N1, the 218–amino acid residue receptor-binding domain (RBD) of SARS coronavirus expressed in yeast–Pichia pastoris X-33. When adjuvanted with aluminum hydroxide, this protein elicited high neutralizing antibody titers and high RBD-specific antibody titers. However, the yield of RBD219-N1 (60 mg RBD219-N1 per liter of fermentation supernatant; 60 mg/L FS) still required improvement to reach our target of >100 mg/L FS. In this study, we optimized the 10 L scale production process and increased the fermentation yield 6- to 7-fold to 400 mg/ L FS with purification recovery >50%. A panel of characterization tests indicated that the process is reproducible and that the purified, tag-free RBD219-N1 protein has high purity and a well-defined structure and is therefore a suitable candidate for production under current Good Manufacturing Practice and future phase-1 clinical trials.

fVaccines have been at the forefront of global research efforts to combat malaria, yet despite several vaccine candidates, this goal has yet to be realized. A potentially effective approach to disrupting the spread of malaria is the use of transmissionblocking vaccines (TBV), which prevent the development of malarial parasites within their mosquito vector, thereby abrogating the cascade of secondary infections in humans. Since malaria is transmitted to human hosts by the bite of an obligate insect vector, mosquito species in the genus Anopheles, targeting mosquito midgut antigens that serve as ligands for Plasmodium parasites represents a promising approach to breaking the transmission cycle. The midgut-specific anopheline alanyl aminopeptidase N (AnAPN1) is highly conserved across Anopheles vectors and is a putative ligand for Plasmodium ookinete invasion. We have developed a scalable, high-yield Escherichia coli expression and purification platform for the recombinant AnAPN1 TBV antigen and report on its marked vaccine potency and immunogenicity, its capacity for eliciting transmission-blocking antibodies, and its apparent lack of immunization-associated histopathologies in a small-animal model.

The first structure of an S. mansoni venom allergen-like protein is presented.