Part:BBa_K3743016
HBc virus like particles (VLP)
Part Description
VLPs are a class of diverse nanoparticles that are formed by structural viral proteins, such as capsids, and can self-assemble. In spite of their resemblance to viruses, they are noninfectious because they lack viral genetic material. Humans respond to VLPs by displaying a high density of antigenic epitopes that mimic the 3D conformation of native viruses and thereby evoke the desired humoral and cellular responses. HBV's core antigen (HBc) has been extensively used for VLP applications throughout the years. The core antigen of HBV is a protein of 21 kDa that self-assembles to package the viral polymerase and pregenomic RNA during HBV replication by the nucleocapsid particles. It shows ease of recombinant expression and self assembly. Also, it has several characteristics that make it a desirable carrier for foreign haptens. Simply HBcAg acts as a carrier by inserting its peptidic epitopes at different positions. Using this method, foreign haptens will take up the viral neutralizing antibodies binding sites, which will result in reduced HBcAg antigenicity and immunogenicity, and enhanced foreign epitope antigenicity and immunogenicity. 33 years after the first vaccine using this technology was approved by the FDA, vaccines based on virus-like particles have demonstrated their effectiveness in human health.
Usage
We included these VLPs in our circuit as they elicit an immune response without compromising the safety of their recipient as they lack viral genetic material. As exogenous antigens, VLPs are taken up by professional antigen presenting cells (APCs), especially DCs, followed by antigen processing and presentation via MHC class II molecules, DC activation and maturation through up‐regulation of co‐stimulatory molecules and cytokine production, and stimulation of CD4+ T helper cells. All these events can efficiently induce both humoral and cellular immunity. In addition, the exogenous VLPs can enter the cytosol of DCs, be processed and presented by MHC class I molecules to cytotoxic T lymphocytes (CTLs) using cross‐presentation. Furthermore, the B‐cell activation using VLPs is robust enough to induce T cell‐independent IgM antibodies.
Literature Characterization
It has been shown that a shortened form of HBc (aa 1–149) lacking a protamine-like domain (aa150–183) is sufficient for self-assembly into capsid particles. Multi-epitope immunogens of T. gondii-containing truncated HBc VLPs (HBcH82, HBcH301, HBcR82, and HBcR301) demonstrated strong self-assembly and possessed icosahedral morphology identical to the original non-chimeric VLPs (HBc) (figure (1)). These particles were homogeneous in size.(1)
Characterization Of Structural Fitness & Molecular Dynamics
In Our VLPs, we loaded TNBC epitopes, which we used in last year’s project, onto the Hepatitis B core protein. Then, we tested the results’ functional stability and molecular dynamics and made comparisons between them depending of the oligomeric structure of the VLP, their sequence coverage, predicted IDDT per position, RMSD, RMSF and predicted alignment error.
Figure 2. Illustrates VLPs compared based on their structural fitness and molecular dynamics. The first row in each figure illustrates the oligomeric structure of our VLPs after loading the epitopes on the HBc. The second row shows the sequence coverage and predicted IDDT per position for each VLP. The third and fourth rows show the RMSD and RMSF which calculate the stability and the flexibility of the VLPs respectively. The fifth and final row show the predicted alignment errors.
References
1. Guo, J., Zhou, A., Sun, X., Sha, W., Ai, K., Pan, G., ... & He, S. (2019). Immunogenicity of a virus-like-particle vaccine containing multiple antigenic epitopes of toxoplasma gondii against acute and chronic toxoplasmosis in mice. Frontiers in immunology, 10, 592. Sequence and Features
- 10INCOMPATIBLE WITH RFC[10]Illegal PstI site found at 290
- 12INCOMPATIBLE WITH RFC[12]Illegal PstI site found at 290
- 21INCOMPATIBLE WITH RFC[21]Illegal BamHI site found at 446
- 23INCOMPATIBLE WITH RFC[23]Illegal PstI site found at 290
- 25INCOMPATIBLE WITH RFC[25]Illegal PstI site found at 290
- 1000INCOMPATIBLE WITH RFC[1000]Illegal BsaI site found at 429
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