Eliciting an antibody response against a recombinant TSH containing fusion protein

Recombinant subunits of SARS‐CoV‐2 spike protein as vaccine candidates to elicit neutralizing antibodies

Objectives

The spike protein has been reported as one of the most critical targets for vaccine design strategies against the SARS‐CoV‐2 infection. Hence, we have designed, produced, and evaluated the potential use of three truncated recombinant proteins derived from spike protein as vaccine candidates capable of neutralizing SARS‐CoV‐2 virus.

Methods

In silico tools were used to design spike‐based subunit recombinant proteins (RBD (P₁), fusion peptide (P₂), and S1/S2 cleavage site (P₃)). These proteins were checked for their ability to be identified by the anti‐SARS‐CoV‐2 antibodies by exposing them to COVID‐19 serum samples. The proteins were also injected into mice and rabbit, and the antibody titers were measured for 390 days to assess their neutralization efficiency.

Results

The antibodies that existed in the serum of COVID‐19 patients were identified by designed proteins. The anti‐spike antibody titer was increased in the animals injected with recombinant proteins. The VNT results revealed that the produced antibodies could neutralize the cultured live virus.

Conclusion

Truncated subunit vaccines could also be considered as robust tools for effective vaccination against COVID‐19. Using a combination of in silico, in vitro, and in vivo experiments, it was shown that the injection of spike‐based truncated recombinant proteins could stimulate long‐lasting and neutralizing antibody responses.

In silico design and in vitro characterization of a recombinant antigen for specific recognition of NMP22

Although urine cytology and cystoscopy are current gold standard methods in diagnosis and surveillance of Bladder cancer (BC), they have some limitations which necessitates novel diagnostic approaches to compensate their drawbacks. In this regard, Nuclear Matrix Protein 22 (NMP22) is introduced as a potential tumor biomarker for BC detection (FDA approved). NMP22 determination mainly occurs through immunoassay platforms, raising a proper antibody against its antigen. Hence, development of such immunoassays seems crucial. Various bioinformatic tools were harnessed to select a region with lowest variability, highest density for linear and conformational epitopes, lowest post translational modifications, highest antigenicity, best physicochemical properties and reliable transcriptional properties. Subsequently, E. coli BL21 (DE3) and P. pastoris GS115 were applied for exogenous expression. Ultimately, protein purification and quantification was followed by ELISA test for antibody analyses. Both host successfully expressed the antigen, while the E. coli expression was with higher yield. The commercial anti-NMP22 antibodies showed relatively equal detection results. However, the slight better detection for the antigen with P. pastoris origin could be deduced as better structural properties for P. pastoris. These results indicate higher expression yields and lower costs for over-expression of this eukaryotic antigen.

Production and Characterization of Monoclonal and Polyclonal Antibodies Against Truncated Recombinant Dickkopf-1 as a Candidate Biomarker

Several studies have reported an increased serum level of Dickkopf (DKK-1) protein in a variety of cancers, including multiple myeloma, lung, colorectal, bone loss, and Alzheimer's disease. This protein has potential to be used as a biomarker for the diagnosis of some cancers, especially bone loss in multiple myeloma. In the present study, to measure the concentration level of DKK-1 protein, rabbit polyclonal antibody (pAb) and mouse monoclonal antibodies (mAbs) were produced against this protein. New Zealand white rabbits and BALB/c mice were immunized with the chimeric recombinant DKK-1 antigen. Immunized mouse spleen cells were fused with SP2/0 cells to generate anti-rDKK-1 antibody-producing hybridoma cells. Antibodies were purified by protein A affinity chromatography and assessed using sodium dodecyl sulfate polyacrylamide gel, western blotting and enzyme-linked immunosorbent assay. These results implied that the pAb and mAb were produced against the DKK-1 protein. The Kd value of 5 × 10^-9 M was recorded for the mAb MR6F3 toward native DKK-1, and the Ig isotype was identified as IgG2b. No cross-reactivity was shown with DKK-2 by MR6F3. Collectively, our results revealed that the produced pAb and mAb could be used in the measurement of DKK-1 protein.