The significant decrease in protection against WT pseudovirus by RBD-Beta vaccine suggested that a single variant-based vaccine may not be sufficient to induce cross-neutralizing activity

The significant decrease in protection against WT pseudovirus by RBD-Beta vaccine suggested that a single variant-based vaccine may not be sufficient to induce cross-neutralizing activity. vaccine of RBD-Beta and RBD-wild type could be a possible broad-spectrum vaccination strategy. Keywords: SARS-CoV-2, RBD, subunit vaccine, bivalent vaccine, glycoengineered yeast 1. Introduction Coronavirus disease 2019 (COVID-19) is usually a highly infectious disease caused by severe acute respiratory syndrome coronavirus type II (SARS-CoV-2), which to date has globally caused over six billion infections and over six million deaths,1 posing a huge threat to public health security. SARS-CoV-2 contains a trimeric surface spike protein (S), which consists of an S1 subunit that binds to the host cell and an S2 subunit that fuses to the cell membrane (Gst?ttner et al., 2021). The S2 subunit mediates membrane fusion, allowing the computer virus to invade the host cell (Lan et al., 2020), thereby enabling contamination of the human body and triggering a series of changes Z-YVAD-FMK in bodily functions (Harrison et al., 2020). The wide range of hosts and the coronavirus genomic structure make it susceptible to genetic mutations and recombination, and consequently Z-YVAD-FMK they exhibit a rich genetic diversity, enabling several SARS-CoV-2 variants to escape immunity and become difficult to inhibit even using vaccines (Harvey et al., 2021; Hoffmann et al., 2021; Souza et al., 2022; Zhang et al., 2022). The World Health Business classifies variants into two categories, variants of concern (VOCs) and variants of interest (VOIs), with VOCs being more infectious and drug-resistant than VOIs are. Delta and Omicron, which emerged in November 2021 with a large number of mutated sites and a rapid increase in cases, are all VOCs. Current vaccines are not sufficiently protective against Omicron (Planas et al., 2022). In particular, vaccine protection against the BA.4 and BA.5 variants was significantly decreased (Tuekprakhon et al., 2022), and it is difficult for vaccine development to maintain pace with viral antigenic change. The receptor binding domain name (RBD) is considered an ideal antigen for vaccine design because of the predominantly neutralizing epitopes (Kuo et al., 2020; Arunachalam et al., 2021). Three of the mutation sites located in the RBD region of Beta variant, K417N, E484K, and N501Y, alter the computer virus transmission capacity (Tegally et al., 2021; Yuan et al., 2021) and can cause immune escape (Moyo-Gwete et al., 2021), resulting in reduced protection of vaccines (Wang et al., 2021; Cameroni et al., Z-YVAD-FMK 2022). It is therefore advantageous to consider the development of multivalent vaccines. Our laboratory previously knocked out the Z-YVAD-FMK excessive mannosylation modification pathway of the yeast expression system and reconstructed the mammalian glycosylation modification pathway based on yeast glycosyl engineering. Based on this platform, we used glycoengineered yeast to rapidly and efficiently express recombinant RBD of SARS-CoV-2 (Liu et al., 2022). Here, we developed a specific vaccine against SARS-CoV-2 Beta variant. During this research, we found that the sera Z-YVAD-FMK of RBD-Beta vaccine-immunized mice had a significantly reduced neutralizing activity against SARS-CoV-2 wild type (WT) pseudovirus. Consequently, we prepared a bivalent vaccine using the SARS-CoV-2 RBD-WT and RBD-Beta with Al(OH)3 and CpG double adjuvants for immunization of BALB/c mice. The results showed that this bivalent vaccine exhibited a degree of broad-spectrum neutralizing activity. 2. Materials and methods 2.1. has been described previously (Choi et al., 2003). was cultivated in yeast peptone dextrose medium at 25C. Trans5 (TransGen Biotech, Beijing, China) was cultured in Luria-Bertani medium at 37C. Yeast extract, agar, and tryptone were obtained from OXOID (Basingstoke, United Kingdom); NaCl was purchased from SINOPHARM (Shanghai, China). Hygromycin B, zeocin, and G418 were obtained from Thermo Fisher (MA, United States). 2.2. RBD-Beta protein expression, fermentation, and purification The SARS-CoV-2 RBD gene (GenBank accession number MN908947.3) was synthesized, ligated into the pPICZA vector, and subsequently transferred into glycoengineered cells and RBD-wild type protein (RBD-WT) was successfully expressed and purified (Liu et al., 2022). Mouse monoclonal to HDAC3 The gene sequence of K417N, E484K, and N501Y sites were mutated, and the target gene was cloned to generate expression vector pPICZA-RBD-Beta..