ABSTRACT
Protein nanoparticles (NPs) can be used as vaccine platforms for target antigen presentation. Aim: To conduct a proof-of-concept study to demonstrate that an effective NP platform can be built based on a short self-assembling peptide (SAP) rather than a large self-assembling protein. Materials & methods: SUMO-based protein fusions (SFs) containing an N-terminal SAP and a C-terminal antigen were designed, expressed in Escherichia coli and purified. The structure was investigated by electron microscopy. The antibody response was tested in mice after two adjuvant-free immunizations. Results: Renatured SFs form fiber-like NPs with the antigen exposed on the surface and induce a significant antibody response with a remarkably high target-to-platform ratio. Conclusion: The platform is effective and has considerable potential for modification toward various applications, including vaccine development.
We aimed to extend the arsenal of protein platforms used for vaccine development. To this end, in this proof-of-concept study we constructed new self-assembling fusion proteins consisting of three modules. Module 1 is responsible for the self-assembly, while modules 2 and 3 are responsible for the immune response. Modules 1 and 2 form the platform, while module 3 represents the target antigen exposed on the surface of the self-assembled nanoparticles. After conventional biosynthesis in Escherichia coli, the proteins undergo efficient self-assembly during purification, and the resulting nanoparticles elicit a strong immune response without using an enhancing agent (adjuvant). The simple modular design and a high target-to-platform ratio of the immune response make our system a promising approach for practical applications, including vaccine development.
Subject(s)
Nanoparticles , Vaccines , Adjuvants, Immunologic , Animals , Antigen Presentation , Mice , Nanoparticles/chemistry , PeptidesABSTRACT
A novel methanol assimilating yeast species Komagataella kurtzmanii is described using the type strain VKPM Y-727 (=KBP Y-2878 = UCD-FST 76-20 = Starmer #75-208.2 = CBS 12817 = NRRL Y-63667) isolated by W.T. Starmer from a fir flux in the Catalina Mountains, Southern AZ, USA. The new species is registered in MycoBank under MB 803919. The species was differentiated by divergence in gene sequences for D1/D2 LSU rRNA, ITS1-5.8S-ITS2, RNA polymerase subunit I, translation elongation factor-1α and mitochondrial small subunit rRNA. K. kurtzmanii differs from its phenotypically similar sibling species Komagataella pastoris, Komagataella pseudopastoris, Komagataella phaffii, Komagataella populi and Komagataella ulmi by absence of growth at 35 °C and inability to assimilate trehalose.
Subject(s)
Saccharomycetales/classification , Saccharomycetales/genetics , Arizona , Cluster Analysis , DNA, Fungal/chemistry , DNA, Fungal/genetics , DNA, Mitochondrial/chemistry , DNA, Mitochondrial/genetics , DNA, Ribosomal/chemistry , DNA, Ribosomal/genetics , DNA, Ribosomal Spacer/chemistry , DNA, Ribosomal Spacer/genetics , DNA-Directed RNA Polymerases/genetics , Environmental Microbiology , Genes, rRNA , Methanol/metabolism , Microscopy , Molecular Sequence Data , Mycological Typing Techniques , Peptide Elongation Factor 1/genetics , Phylogeny , RNA, Fungal/genetics , RNA, Ribosomal/genetics , RNA, Ribosomal, 5.8S/genetics , Saccharomycetales/metabolism , Sequence Analysis, DNAABSTRACT
In vivo and in vitro experiments showed that human serum albumin (HSA) co-precipitated with components of the commonly used yeast peptone dextrose (YPD) growth medium in aqueous solutions at pH <5. Yeast extract was found to be the primary component of YPD responsible for HSA precipitation. Among yeast extract constituents, RNAs are likely to be most important for HSA precipitation. HSA precipitation at pH <5 was reversible, so that HSA was easily re-solubilized by increasing pH above 6 with completely retained immunoreactivity. The co-precipitation and re-solubilization of HSA were solely pH-dependent and occurred almost instantly at room temperature. Practical aspects of the observed HSA co-precipitation are discussed.
