The Protective Efficacy of a SARS-CoV-2 Vaccine Candidate B.1.351V against Several Variant Challenges in K18-hACE2 Mice.

The emergence of SARS-CoV-2 variants of concern (VOCs) with increased transmissibility and partial resistance to neutralization by antibodies has been observed globally. There is an urgent need for an effective vaccine to combat these variants. Our study demonstrated that the B.1.351 variant inactivated vaccine candidate (B.1.351V) generated strong binding and neutralizing antibody responses in BALB/c mice against the B.1.351 virus and other SARS-CoV-2 variants after two doses within 28 days. Immunized K18-hACE2 mice also exhibited elevated levels of live virus-neutralizing antibodies against various SARS-CoV-2 viruses. Following infection with these viruses, K18-hACE2 mice displayed a stable body weight, a high survival rate, minimal virus copies in lung tissue, and no lung damage compared to the control group. These findings indicate that B.1.351V offered protection against infection with multiple SARS-CoV-2 variants in mice, providing insights for the development of a vaccine targeting SARS-CoV-2 VOCs for human use.

Quantitation of Enterovirus A71 Empty and Full Particles by Sedimentation Velocity Analytical Ultracentrifugation.

The enterovirus A71 (EV71) inactivated vaccine is an effective intervention to control the spread of the virus and prevent EV71-associated hand, foot, and mouth disease (HFMD). It is widely administered to infants and children in China. The empty particles (EPs) and full particles (FPs) generated during production have different antigenic and immunogenic properties. However, the antigen detection methods currently used were established without considering the differences in antigenicity between EPs and FPs. There is also a lack of other effective analytical methods for detecting the different particle forms, which hinders the consistency between batches of products. In this study, we analyzed the application of sedimentation velocity analytical ultracentrifugation (SV-AUC) in characterizing the EPs and FPs of EV71. Our results showed that the proportions of the two forms could be quantified simultaneously by SV-AUC. We also determined the repeatability and accuracy of this method and found that both parameters were satisfactory. We assessed SV-AUC for bulk vaccine quality control, and our findings indicated that SV-AUC can be used effectively to analyze the percentage of EPs and FPs and monitor the consistency of the process to ensure the quality of the vaccine.

The immunogenicity of Alum+CpG adjuvant SARS-CoV-2 inactivated vaccine in mice.

The ongoing evolution and emergence of SARS-CoV-2 variants have raised concerns regarding the efficacy of existing vaccines and therapeutic agents. This study aimed to investigate the immunogenicity of an aluminum hydroxide (Alum) and CpG adjuvanted inactivated vaccine (IAV) candidate against SARS-CoV-2 in mice. A comparison was made between the immune response of mice vaccinated with the Alum+CpG adjuvant IAV and those vaccinated with the Alum adjuvant IAV. Mice immunized with Alum+CpG adjuvant IAV demonstrated high antibody titers and a durable humoral immune response, as well as a Th1-type cellular immune response. Notably, compared to Alum alone vaccine, the Alum+CpG adjuvant IAV induced significantly higher proportions of GC B cells in the splenocytes of immunized mice. Importantly, the changes in inflammatory cytokine levels in the sera of mice vaccinated with the Alum+CpG adjuvant IAV followed a similar trend to that of the Alum adjuvant IAV, which had been proven safe in clinical trials. Overall, our results demonstrate that Alum+CpG adjuvant has the potential to serve as a novel adjuvant, thereby providing valuable insights into the development of vaccine formulations.