Investigation of Kluyveromyces marxianus as a novel host for large-scale production of porcine parvovirus virus-like particles
Abstract Background: Porcine Parvovirus (PPV) is a Parvovirinae virus that can cause embryonic and fetal loss and death and mummification in affected fetal pigs. Unlike conventional vaccines, virus-like particles (VLPs) inherit the natural structure of their authentic virions and highly immunostimulatory that can induce strong humoral immune and T cell responses with no risk of pathogenicity due to incomplete attenuation or inactivation. Production PPV VLPs is still a challenge using the traditional expression platforms due to the low yield and culture cost. Kluyveromyces marxianus is a safe and fast-growing eukaryote that can yield high biomass in low-cost cultures. In this study, we investigated the production and downstream processes of PPV VLPs in K. marxianus, and the potential for effective stand-alone vaccines.Results: After optimization according to the codon bias of K.marxianus, the VP2 protein from Kresse strain was highly expressed. In 5L fermentator, the yield of PPV VLPs reached 2.5 g/L, qualified by HPLC, using a defined mineral medium after 48h fermentation. Two strategies, cation exchange chromatography coupled with Sephacryl® S-500 HR chromatography for the supernatants of pH adjusted cell lysates and anion exchange chromatography followed by cross-flow diafiltration for the precipitate respectively, were established to purify the intracellular PPV VLPs. The purity PPV VLPs reached about 95%, and total recovery was more than 60%. Sera from the PPV VLPs immunized mice showed high titers of IgG antibody and hemagglutination inhibitions on both swine and guinea pig erythrocytes. Spleen lymphocyte proliferation and cytokines detection suggested the PPV VLPs produced by K.marxianus can provoke the cellular immune and humoral immunity responses.Conclusion: This is the highest production of recombinant PPV VLPs achieved to date. The superiorities, safe, high production, short lead time, and low cost, make K. marxianus a greatly competitive platform in bioproduction of PPV VLPs vaccine.