ABSTRACT
Objective:To construct and purify four respiratory syncytial virus (RSV) PreF proteins through gene sequence design and optimization and evaluate their immunogenicity.Methods:Coronin-1A and T4 trimer protein gene sequences were optimized with Human and CHO codons, and then added to RSV F protein sequence. The above plasmids were transfected into Expi293F cells for protein expression. After purification by nickel column, four trimer proteins were prepared. SDS-PAGE and Western blot were performed for protein identification. BALB/c mice were immunized at week 0 and week 3, and blood samples were collected to measure the activities of binding and neutralizing antibodies in serum.Results:SDS-PAGE and Western blot showed that the four proteins had stable trimer structure. Antigen-antibody affinity test showed that the four trimer proteins had strong affinity with RSV-specific monoclonal antibodies 8897, D25, Motavizumab, AM14 and Palivizumab. The titers of antibodies induced by the two T4 trimers were higher after the initial immunization, while there was a substantial increase in the titers of antibodies induced by Human codon-optimized trimer protein after the second immunization.Conclusions:PreF trimer protein can be prepared by adding any of the two different heterotrimer motifs, and induce effective binding and neutralizing antibodies in mice.
ABSTRACT
Objective:To compare the immunogenicity of the prefusion (PreF) and postfusion (PostF) conformations of the respiratory syncytial virus (RSV) F protein.Methods:The expression of PreF and PostF recombinant proteins was analyzed by SDS-PAGE and Western blot. The binding affinity between F protein and its specific antibodies was detected by Octet. The binding antibodies and neutralizing antibodies in immune serum were detected after immunizing mice with PreF or PostF recombinant protein.Results:PreF protein was stable in the form of a trimer after modification with higher binding affinity with monoclonal antibodies such as D25, 8897, AM14, Palivizumab and Motavizumab. PostF protein lacked the antigenic site ? and showed a monomer conformation. Besides, it was unable to bind to D25, 8897 and AM14 antibodies. Animal experiments showed that AS01 adjuvant was better than aluminum adjuvant in inducing binding antibodies and neutralizing antibodies against RSV Long strains. The binding antibodies induced by PreF and PostF recombinant proteins had similar binding ability to PreF protein, while the binding antibodies induced by PostF recombinant protein showed stronger binding ability to PostF than to PreF.Conclusions:PreF has more epitopes and the trimer form of PreF recombinant protein after modification is more stable and can induce stronger neutralizing antibodies. Moreover, the immunopotentiating effect of AS01 adjuvant is better than that of aluminum adjuvant. Therefore, stabilization-based trimer structure modification of PreF and the development of adjuvants are crucial for the development of RSV vaccines.
ABSTRACT
With the relatively serious global epidemic outbreak of SARS-CoV-2 infection, public concerns focus on not only clinical therapeutic measures and public quarantine for this disease but also the development of vaccines. The technical design of our SARS-CoV-2 inactivated vaccine provides a viral antigen that enables the exposure of more than one structural protein based upon the antibody composition of COVID-19 patients convalescent serum. This design led to valid immunity with increasing neutralizing antibody titers and a CTL response detected post-immunization of this vaccine by two injections in rhesus macaques. Further, this elicited immunoprotection in macaques enables not only to restrain completely viral replication in tissues of immunized animals, compared to the adjuvant control and those immunized by an RBD peptide vaccine, but also to significantly alleviate inflammatory lesion in lung tissues in histo-pathologic detection, compared to the adjuvant control with developed interstitial pneumonia. The data obtained from these macaques immunized with the inactivated vaccine or RBD peptide vaccine suggest that immunity with a clinically protective effect against SARS-CoV-2 infection should include not only specific neutralizing antibodies but also specific CTL responses against at least the S and N antigens.
