June 12 – 17, 2022
Modular virus-like-particles (VLPs), presenting foreign antigens on their surface, are promising candidates for a wide range of future vaccines. A viable production pathway is the expression and purification of viral structural proteins and their subsequent in vitro assembly into VLPs, in a bioprocess environment. One promising approach is the use of murine polyomavirus major capsid protein VP1 as a carrier of modular epitopes from vaccine targets. This platform technology uses E. coli as an expression system and showed promising results in creating VLP vaccines candidates directed at influenza, Group A Streptococcus and other infectious pathogens. However, like other viral capsomeres and viral structures, purification using chromatography techniques remains a challenge as conventional high capacity ion exchange matrices suffer from low binding capacities.
In this work the role of DNA-protein interaction during the purification of VLP precursor capsomeres is investigated. It is found that modular VP1 capsomeres coat DNA molecules forming large DNA-protein complexes that are unable to access the pores of chromatographic resins resulting in inefficient column binding. By increasing the salt concentration of the buffer above 0.3M NaCl, the DNA-protein complexes dissociate. At intermediate salt concentrations salt-tolerant ion-exchange resins can be used to efficiently capture and purify VP1 capsomeres, as the salt breaks the aggregates but is insufficient to interfere with binding to the salt-tolerant matrix. This approach increases the binding capacity of VLP precursor proteins by at least a magnitude over published laboratory-based methods.
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Lukas Gerstweiler,; Jingxiu Bi; Linda Lua; and Anton Middelberg, "Influence of DNA-protein interactions on purification and assembly of virus-like particles" in "Vaccine Technology VIII", Tarit Mukhopadhyay, Merck Research Laboratories, USA; Charles Lutsch, Sanofi Pasteur, France; Linda Hwee-Lin Lua, University of Queensland, Australia; Francesc Godia, Universitat Autònoma de Barcelona, Spain Eds, ECI Symposium Series, (2022). https://dc.engconfintl.org/vaccine_viii/83