Global delivery of vaccines would benefit from ultra low-cost prices (less than 15 cents per dose) at intermediate scales of production (10-100 million annual doses). Currently, for vaccines comprising recombinant proteins, the cost of manufacturing remains higher than these targets. Protein subunit vaccines are increasing in prevalence due to enhanced safety and understanding of epitopes and immune response. Extensive characterization has enabled recent work in rational design and scaffolding of vaccines. While promising for function and efficacy, current designed therapeutics are subject to the same manufacturing challenges as biopharmaceuticals. Thus, the key drivers of cost include volumetric productivity, quality, and product stability. Here, we present an approach that uses bioinformatics to improve the expression, quality, and stability of a subunit vaccine for rotavirus gastroenteritis. Currently, three serotypes of a truncated VP8 rotavirus subunit protein are in clinical development. We expressed each serotype in the alternative yeast host Komagataella phaffii (Pichia pastoris), which boasts high growth rates, simple genetic manipulation, and is Generally Recognized as Safe (GRAS) by the FDA. The small genome size and fast iteration time for expression of new products (~4 weeks) enabled a bioinformatics-based approach for rational product engineering. With minimal, targeted sequence modifications we successfully mitigated different manufacturing challenges encountered with each serotype, including glycosylation, aggregation, truncation, and low expression. Finally, we were able to reduce process cycles and cost by co-expression of high quality serotypes. This case study motivates manufacturability as a key component of protein therapeutic development.

Engineering quality and manufacturability of a trivalent protein subunit vaccine

2019 Spring National Meeting

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