ABSTRACT
BackgroundThe ReCOV is a recombinant trimeric two-component SARS-CoV-2 subunit vaccine adjuvanted with BFA03. We report the preliminary safety and immunogenicity results for the ReCOV. MethodsThis first in human, randomized, double-blind, placebo-controlled phase I study, was conducted at 2 study sites in New Zealand. Subjects were stratified into two age cohorts (18-55 years and 56-80 years old) and then randomly assigned in a 4:1 ratio to receive two 0.5 mL intramuscular doses of the ReCOV vaccine (20{micro}g or 40{micro}g, adjuvanted with BFA03 in each) or placebo, 21 days apart. The primary endpoints were incidence of solicited local and systemic adverse events (AEs) and unsolicited AEs after each dose; incidence of serious adverse events (SAEs) up to 30 days after the second dose; changes in clinical laboratory tests from baseline up to 7 days after each dose; and changes in vital signs from baseline up to 30 days after the second dose. The key secondary endpoints for immunogenicity were neutralizing antibody titers against SARS-CoV-2, S1 receptor binding domain (RBD) and N-terminal domain (NTD) IgG titers post-vaccination. The T cell-specific immune response elicited by ReCOV were also evaluated. The trial was registered with ClinicalTrials.gov (NCT04818801). FindingsOne hundred participants (50 for each age group) were randomized. The incidence of solicited local AEs in 20g ReCOV, 40g ReCOV, and pooled placebo group among younger adults were 60.0%, 70.0%, and 10.0%, respectively, while among older adults were 55.0%, 84.2%, and 10.0%, respectively. The incidence of solicited systemic AEs in 20g ReCOV, 40g ReCOV, and pooled placebo group among younger adults were 60.0%, 60.0%, and 30.0%, respectively, while among older adults were 50.0%, 52.6%, and 50.0%, respectively. All solicited AEs and unsolicited AEs were mild. No vaccination-related SAE, adverse events of special interest, and AE leading to early discontinuation were reported. ReCOV elicited SARS-CoV-2 neutralizing antibody after the first vaccination, which were increased further after the second vaccination irrespective of dose and age groups. The neutralizing antibody against wild-type SARS-CoV-2 peaked at 14 days post the second vaccination in both 20{micro}g and 40{micro}g ReCOV groups, with GMT of 1643.17 IU/mL and 1289.21 IU/mL among younger adults, and 1122.32 IU/mL and 680.31 IU/mL among older adults, respectively. Similarly, both anti-RBD and anti-NTD specific IgG were elicited after the first vaccination, and peaked at 14 days after the second vaccination. T helper 1 biased cellular responses were observed after ReCOV vaccinations. InterpretationBoth 20 and 40{micro}g ReCOV showed good safety profiles and elicited strong immune responses in the younger and the older adults. The results of this study support the accelerated development of ReCOV. FundingJiangsu Recbio Technology Co., Ltd.
ABSTRACT
Advanced mRNA vaccines play vital roles against SARS-CoV-2. However, due to their poor stability, most current mRNA delivery platforms need to be stored at -20{degrees}C or -70{degrees}C, which severely limits their distribution. Herein, we present lyophilized SARS-CoV-2 mRNA-lipid nanoparticle vaccines, which can be stored at room temperature with long-term thermostability. In the in vivo Delta virus challenge experiment, lyophilized Delta variant mRNA vaccine successfully protected mice from infection and cleared the virus. Lyophilized omicron mRNA vaccine enabled to elicit both potent humoral and cellular immunity. In booster immunization experiments in mice and old monkeys, lyophilized omicron mRNA vaccine could effectively increase the titers of neutralizing antibodies against wild-type coronavirus and omicron variants. In humans, lyophilized omicron mRNA vaccine as a booster shot could also engender excellent immunity and had less severe adverse events. This lyophilization platform overcomes the instability of mRNA vaccines without affecting their bioactivity, and significantly improved their accessibility, particularly in remote regions.
ABSTRACT
Recombinant human interferon α2b(rhIFNα2b)is widely used as an antiviral therapy agent for the treatment of hepatitis B and hepatitis C.The current identification test for rhIFNα2b is complex.In this study,an anti-rhIFNα2b nanobody was discovered and used for the development of a rapid lateral flow strip for the identification of rhIFNα2b.RhIFNα2b was used to immunize an alpaca,which established a phage nanobody library.After five steps of enrichment,the nanobody I22,which specifically bound rhIFNα2b,was isolated and inserted into the prokaryotic expression vector pET28a.After subsequent purification,the physicochemical properties of the nanobody were determined.A semiquantitative detection and rapid identification assay of rhIFNα2b was developed using this novel nanobody.To develop a rapid test,the nanobody I22 was coupled with a colloidal gold to produce lateral-flow test strips.The developed rhIFNα2b detection assay had a limit of detection of 1 μg/mL.The isolation of I22 and successful construction of a lateral-flow immunochromatographic test strip demonstrated the feasibility of performing ligand-binding assays on a lateral-flow test strip using recombinant protein products.The principle of this novel assay is generally applicable for the rapid testing of other com-mercial products,with a great potential for routine use in detecting counterfeit recombinant protein products.
ABSTRACT
The coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has led to significant public health, economic and social problems. Development of effective vaccines is still a priority to contain the virus and end the global pandemic. In this study, we reported that ReCOV, a recombinant trimeric NTD and RBD two-component SARS-CoV-2 subunit vaccine adjuvanted with BFA03 (an AS03-like squalene adjuvant), induced high levels of neutralizing antibodies against SARS-CoV-2 and the circulating variants in mice, rabbits and rhesus macaques. Notably, two-dose immunizations of ReCOV provided complete protection against challenge with SARS-CoV-2 in hACE2 transgenic mice and rhesus macaques, without observable antibody-dependent enhancement of infection. These results support further clinical development of ReCOV and the vaccine is currently being evaluated in a phase I clinical trial in New Zealand (NCT04818801).
ABSTRACT
<p><b>OBJECTIVE</b>To study the expression of Toll-like receptors (TLRs) mRNA in human trophoblast HTR-8/SVneo cells and the changes in indoleamine 2,3-dioxygenase (IDO) mRNA expression in response to TLR ligand stimulation.</p><p><b>METHODS</b>The expressions of TLRs and IDO mRNA in human HTR-8/SVneo cells were tested by RT-PCR, and the changes in IDO mRNA levels after exposure to TLR3, TLR4, TLR7/8, and TLR9 ligands were quantitatively analyzed with real-time PCR.</p><p><b>RESULTS</b>IDO and TLR1-10 mRNAs were expressed in HTR-8/SVneo cells. As the cell culture time extended, IDO mRNA expression level tended to increase within 48 h. After stimulation with the TLR ligands, the expression of TLR-3 mRNA was down-regulated while the expression of TLR-4, 7, 8, and 9 mRNA up-regulated. Stimulation of the cells with poly(I:C) lowered the expression of IDO mRNA while IFN-γ increased its expression.</p><p><b>CONCLUSIONS</b>The expression of IDO mRNA is associated with the nutrition of the maternal-fetal interface. Stimulation with the TLR ligands affects the expression of IDO and TLR mRNA expressions in the cells, which verifies the functional activity of TLRs and suggests a role of IDO in TLR pathway-dependent antiviral immunity.</p>
