Optimization of SARS-CoV-2 spike protein receptor binding domain expression in Pichia pastoris and evaluation of its immunogenicity / 中华微生物学和免疫学杂志

Objective:To effectively express the receptor binding domain (RBD) of SARS-CoV-2 spike protein in Pichia pastoris and to evaluate its immunogenicity. Methods:The gene encoding the RBD protein was synthesized and cloned into the pPICZαA plasmid. After linearization, the plasmid was transferred and integrated into the genome of Pichia pastoris. The expressed RBD protein in culture supernatant was analyzed by Western blot and Biolayer interferometry. After screening, a single clone expressing the RBD protein was selected. The high-level expression of RBD protein was achieved by optimizing the fermentation process, including the salt concentration adjusting of the medium and induction condition optimization (pH, temperature and duration). The immunogenicity of the expressed RBD protein was evaluated in a mouse model. Results:A single clone with a high expression level of RBD protein was obtained and named RBD-X33. The expression level of RBD protein in the fermentation supernatant reached up to 240 mg/L after optimization of the induction condition (HBSM medium, pH=6.5±0.3, 22℃ and 120 h). In the mouse experiment, the recombinant RBD protein was formulated with Alum+ CpG dual adjuvant and injected into mice. The binding IgG antibody levels were up to 2.7×10 6 tested by ELISA and the neutralizing antibody levels were up to 726.8 tested by live virus neutralizing antibody assay (prototype). Conclusions:The RBD protein could be efficiently expressed in Pichia pastoris and induce stronger immune response in animals. This study suggested that the recombinant SARS-CoV-2 RBD protein expressed in Pichia pastoris could serve as a candidate antigen in the development of SARS-CoV-2 vaccine.

Immune response induced by 14-3-3.3 recombinant protein vaccine of Taenia solium in mice / 中华地方病学杂志

Objective:To explore the potential of Taenia solium (Ts) 14-3-3.3 protein as a candidate molecule for cysticercosis vaccine. Methods:Sixty Kunming mice with the body weight of 18 - 22 g were selected and divided into 3 groups according to their body weight via the random number table method, including normal saline control group (control group), Ts14-3-3.3 recombinant protein vaccine group (vaccine group), and Ts14-3-3.3 recombinant protein vaccine + adjuvant group (vaccine + adjuvant group), with 20 mice in each group. The multi-point subcutaneous injection method was adopted. After the first immunization at 0 week, the booster immunization was carried out twice, a total of 3 times, with an interval of 2 weeks. Four mice in the three groups were killed at 0, 2, 4, 6 and 8 weeks after the first immunization, and the blood of eyeballs and spleen were collected aseptically for serum separation and preparation of spleen lymphocytes suspension [treatment: cell suspension, antigen-stimulate and concanavalin (Con) A-stimulate], respectively. The levels of mouse serum specific immunoglobulin (Ig) G, IgG2a, IgG1 and IgE were detected by indirect enzyme-linked immunosorbent assay (ELISA). The proliferation level of mouse spleen lymphocytes was detected via the CCK-8 method. The levels of tumor necrosis factor (TNF)-α, interleukin (IL)-12, IL-13 and IL-10 in culture supernatant of mouse spleen lymphocytes were determined by double-antibody sandwich ELISA.Results:The IgG, IgG2a, and IgG1 levels of the vaccine and vaccine + adjuvant groups immunized for 2 to 8 weeks were higher than those of the control group, and the above indicators of the vaccine + adjuvant group were higher than those of the vaccine group ( P < 0.05). With the same treatment between the groups, the proliferation levels of spleen lymphocytes and the levels of TNF-α, IL-12, IL-13, and IL-10 in the culture supernatant after 2 - 8 weeks of immunization were statistically significantly different ( P < 0.05); the proliferation levels of spleen lymphocytes and the levels of TNF-α, IL-12, IL-13 and IL-10 in the culture supernatant of the vaccine and vaccine + adjuvant groups immunized for 2 to 8 weeks were higher than those of the control group, and the above indicators of the vaccine + adjuvant group were higher than those of the vaccine group ( P < 0.05). When treatment was different in the group, the proliferation levels of spleen lymphocytes and the levels of TNF-α, IL-12, IL-13 and IL-10 in the culture supernatant of the antigen-stimulate and ConA-stimulate were higher than those of the cell suspension, and the above indicators of the ConA-stimulate were higher than those of the antigen-stimulate ( P < 0.05). Conclusion:The recombinant protein vaccine of Ts14-3-3.3 can induce an effective immune response in mice.

Progress and analysis on the development of 2019-nCoV vaccine / 生物医学工程学杂志

As the COVID-19 pandemic is intensifying globally, more and more people are pinning their hopes on the development of vaccines. At present, there are many research teams who have adopted different vaccine technology routes to develop 2019-nCoV vaccines. This article reviews and analyzes the current development and research status of 2019-nCoV vaccines in different routes, and explores their possible development in the future.

Recombinant DNA and Protein Vaccines for Foot-and-mouth Disease Induce Humoral and Cellular Immune Responses in Mice

BACKGROUND: Foot-and-mouth disease virus (FMDV) is a small single-stranded RNA virus which belongs to the family Picornaviridae, genus Apthovirus. It is a principal cause of FMD which is highly contagious in livestock. In a wild type virus infection, infected animals usually elicit antibodies against structural and non-structural protein of FMDV. A structural protein, VP1, is involved in neutralization of virus particle, and has both B and T cell epitopes. A RNA-dependent RNA polymerase, 3D, is highly conserved among other serotypes and strongly immunogenic, therefore, we selected VP1 and 3D as vaccine targets. METHODS: VP1 and 3D genes were codon-optimized to enhance protein expression level and cloned into mammalian expression vector. To produce recombinant protein, VP1 and 3D genes were also cloned into pET vector. The VP1 and 3D DNA or proteins were co-immunized into 5 weeks old BALB/C mice. RESULTS: Antigen-specific serum antibody (Ab) responses were detected by Ab ELISA. Cellular immune response against VP1 and 3D was confirmed by ELISpot assay. CONCLUSION: The results showed that all DNA- and protein-immunized groups induced cellular immune responses, suggesting that both DNA and recombinant protein vaccine administration efficiently induced Ag-specific humoral and cellular immune responses.

Expression and Immune Effect Study of Therapeutic Recombinant Protein Vaccine VP22?-mE6?/mE7 / 中国生物工程杂志

In order to investigate the biological effects of the VP22?-mE6?/mE7 built-in adjuvant fusion protein vaccine on the tumor associated with HPV-16 infection.HSV-1 VP22? and HPV-16 mE6?/mE7 genes were cloned,and the pET28a-VP22?-mE6?/mE7 recombinat prokaryotic expression vector was constructed.Vector was transformed into Rosetta(DE3)E.coli string and expressed under the induction of IPTG.The re-naturalized protein was then purified via Ni2+ affinity adsorbent column and identified by SDS-PAGE and Western blot.Purified protein was immunized BalB/C and C57BL/6 mice to evaluate the immunogenicity and anti-tumor activity.The expressed recombinant protein formed as inclusion body with a prediction MW about 34kDa and contained approximately 45% of total somatic protein.The VP22?-mE6?/mE7 immunization induced higher titer of specific IgG against HPV,higher level of lymphocyte proliferation and better effect on suppressing HPV16 positive TC-1 tumor growth than the mice immunized with mE6?/mE7 alone.The results showed that the recombined built-in adjuvant vaccine could induce specific cellular immune response in vitro and inhibit the TC-1 tumor proliferation in vivo,that would be a foundation for further studies and developments of inner adjuvant vaccines.