Downstream processing for influenza vaccines and candidates: An update

Abstract

Seasonal and pandemic influenza outbreaks present severe health and economic burdens. To overcome limitations on influenza vaccines' availability and effectiveness, researchers chase universal vaccines providing broad, long-lasting protection against multiple influenza subtypes, and including pandemic ones.Novel influenza vaccine designs are under development, in clinical trials, or reaching the market, namely inactivated, or live-attenuated virus, virus-like particles, or recombinant antigens, searching for improved effectiveness; all these bring downstream processing (DSP) new challenges. Having to deal with new influenza strains, including pandemics, requires shorter development time, driving the development of faster bioprocesses. To cope with better upstream processes, new regulatory demands for quality and safety, and cost reduction requirements, new unit operations and integrated processes are increasing DSP efficiency for novel vaccine formats.This review covers recent advances in DSP strategies of different influenza vaccine formats. Focus is given to the improvements on relevant state-of-the-art unit operations, from harvest and clarification to purification steps, ending with sterile filtration and formulation. The development of more efficient unit operations to cope with biophysical properties of the new candidates is discussed: emphasis is given to the design of new stationary phases, 3D printing approaches, and continuous processing tools, such as continuous chromatography. The impact of the production platforms and vaccine designs on the downstream operations for the different influenza vaccine formats approved for this season are highlighted.

Bacterial Ghosts-Based Vaccine and Drug Delivery Systems

“…As such, the structural integrity of surface antigens on most BGs remains intact [8]. The preparation of inactivated vaccines using methods such as formaldehyde and heat treatments can destroy the surface structures of the bacteria [9,10]. Contrarily, BGs prepared by genetic engineering retain all the structural antigens expressed by pathogenic bacteria, which induces very strong, effective humoral and cellular immune responses [11].…”

High‐Yield Separation of Extracellular Vesicles Using Programmable Zwitterionic Coacervates

“…In this study, we functionalized the base material with unpaired charges to perform separation based on similar principles of anion exchange, one of the most common methods used at large scales to isolate biological particles during bioprocessing. [37,[39][40][41][42][43][44] Despite the increasing application of anion exchange chromatography for EVs and virus-like particles, the recovery of particles from columns is often low. Seo et al recently reported that only 66% of loaded EVs can be recovered from a weak anion exchanger using mild elution buffers.…”

“…In this study, we functionalized the base material with unpaired charges to perform separation based on similar principles of anion exchange, one of the most common methods used at large scales to isolate biological particles during bioprocessing. [ 37,39–44 ]…”

Pressure‐dependent fouling behavior during sterile filtration of mRNA‐containing lipid nanoparticles

“…One of the key challenges in mRNA‐based therapeutics is ensuring the effective delivery of the mRNA to the targeted cells (Brader et al, 2021; Carvalho et al, 2021; Rietwyk & Peer, 2017; Schoenmaker et al, 2021). Although several nonviral delivery systems have been developed, including polymer‐based carriers and inorganic nanoparticles, the greatest success has been achieved with lipid nanoparticles (LNPs) (Hajj & Whitehead, 2017; Mitchell et al, 2021; Pardi et al, 2018; Reichmuth et al, 2016; Tenchov et al, 2021; S. Xu, Yang, et al, 2020; Zhou et al, 2020).…”

“…The downstream purification process involves a series of chromatographic separations and tangential flow filtration (Jackson et al, 2020;Rosa et al, 2021;Whitley et al, 2022). The purified mRNA is encapsulated in the LNP by mixing the mRNA (in an acidic aqueous buffer) with the lipids (in ethanol) (Carvalho et al, 2021;Nel & Miller, 2021;Reichmuth et al, 2016). The resulting LNP suspension is buffer exchanged and concentrated by ultrafiltration/diafiltration followed by sterile filtration (Rosa et al, 2021) as part of the final fill-finish operation (Moleirinho et al, 2020;van Reis & Zydney, 2007;Zydney, 2021).…”