Lipid nanoparticles (LNPs) are widely used as delivery systems for mRNA vaccines. The stability and bilayer fluidity of LNPs are determined by the properties and contents of the various lipids used in the formulation system, and the delivery efficiency of LNPs largely depends on the lipid composition. For the quality control of such vaccines, here we developed and validated an HPLC-CAD method to identify and determine the contents of four lipids in an LNP-encapsulated COVID-19 mRNA vaccine to support lipid analysis for the development of new drugs and vaccines.

Introduction: Rabies is a serious public health problem worldwide for which an effective treatment method is lacking but can be prevented by vaccines. Current vaccines are produced in cell or egg cultures, which are both costly and time consuming.Methods: Here, a non-replicating mRNA vaccine (RV021) encoding the rabies virus glycoprotein was developed in vitro, and its immunogenicity and protective efficacy against live virus was evaluated in mice.Results: A two-dose vaccination with 1 μg of RV021 at 7-day intervals induced a protective level of neutralizing antibody that was maintained for at least 260 days. RV021 induced a robust cellular immune response that was significantly superior to that of an inactivated vaccine. Two doses of 1 μg RV021 provided full protection against challenge with CVS of 30~60-fold lethal dose, 50%. Vaccine potency testing (according to the National Institutes of Health) in vivo revealed that the potency of RV021 at 15 μg/dose was 7.5 IU/dose, which is substantially higher than the standard for lot release of rabies vaccines for current human use.Conclusion: The mRNA vaccine RV021 induces a strong protective immune response in mice, providing a new and promising strategy for human rabies prevention and control.

In order to meet the domestic urgent needs of evaluating the immunogenicity of vaccines and the potency testing of therapeutic antibody products against coronavirus disease 2019 (COVID-19), the first Chinese national standards for SARS-CoV-2 neutralizing antibody were established. The potency and stability of the candidate standards were determined by neutralization assay and accelerated degradation study. The stability studies showed that the standards were stable in the short-term. The collaborative study showed that the candidate standards could reduce the variations in neutralization titers between labs and thus improve comparability of neutralizing antibody measurements. Sample 22 has been approved by the Biological Product Reference Standards Sub-Committee of the National Drug Reference Standards Committee as the first Chinese National Standard for Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) neutralizing antibody, with an assigned potency of 1,000 units per milliliter (U/ml). This standard will contribute to the standardized assessment of the quality and efficacy of vaccines and therapeutics for COVID-19 in China.

Background: The Vero cell rabies vaccine is currently the most widely used human rabies vaccine. However, owing to the presence of residual host cell DNA (HCD) in the final product and the potential tumorigenicity of the DNA of high-passage Vero cells, the WHO not only sets a limit on the number of times cells used in production can be passaged, but also imposes strict requirements on the amount of residual HCD in the final vaccine product. Objectives: To systematically reduce the HCD level in the final vaccine product, multiple purification steps are included in the vaccine production process. This study investigated the effectiveness of key production steps in antigen recovery and DNA removal. Methods: The residual HCD fragment content and size distribution were detected using fluorescence quantitative PCR (qPCR) and capillary gel electrophoresis (CGE), and the rabies virus glycoprotein antigen content was detected using enzyme-linked immunosorbent assay (ELISA). The antigen recovery rate and HCD removal rate in each key process were calculated to evaluate the scientific basis and effectiveness of each production step. Additionally, the stability of the process was studied using multiple commercial batches of the product. Results: The results revealed that the total antigen recovery rate in the production process described in this report was no less than 8.5%, and the effective removal rate of residual HCD was not lower than 99.99%. Moreover, the amount of residual HCD in the final product was far below the quality standard of 2 ng/dose, and most of the residual HCD fragments were smaller than 200 bp. The results of the process stability studies on multiple commercial batches showed that the bulk human rabies vaccine produced by this process had excellent safety and efficacy and that the production process was stable and thus suitable for large-scale batch production. Conclusions: The production process described in this study achieved effective recovery of viral antigens and efficient removal of residual HCD, and the process was stable and controllable, enabling the continuous and stable production of vaccine products that meet WHO recommendations and the relevant requirements of the current edition of the Chinese Pharmacopeia. In addition, this study provides theoretical guidance for optimizing the vaccine production process.

Objectives: This study evaluated the 12-month persistence of rabies virus-neutralizing antibody (RVNA) following different immunization regimens of freeze-dried human rabies vaccine (Vero cells) in individuals aged 10–60 years within the Chinese population. Methods: Number of 600 participants from phase III clinical trials who completed the fullimmunization were randomly assigned into one of three groups, four-dose experimental group, five-dose experimental group, and five-dose control group. The experimental group received the vaccine from Shandong Yeedu Biotechnology Co., while the control group used the vaccine from Liaoning Chengda Biotechnology Co., Ltd. The antibody-positive rate and geometric mean concentration (GMC) were calculated, and analysis of variance was used to compare the results among the three groups. Results: The study included 200 participants in the four-dose experimental group, 186 in the five-dose experimental group, and 214 in the five-dose control group. Twelve months post-immunization, the overall RVNA-positive rates were 97.00%, 93.55%, and 94.86% in the four-dose experimental, five-dose control, and five-dose experimental groups, respectively. The GMCs of RVNA were 2.50, 2.05, and 2.04 IU/mL for the respective groups. The age-stratified analysis exhibited high positivity rates across age groups (≤21, 21–50, and ≥50), with rates ranging from 88.4% to 100%, and GMCs were between 1.75 and 2.61 IU/mL. Conclusions: Twelve months after full immunization, the overall RVNA-positive rate remained high across all dosing regimens, demonstrating satisfactory immunogenicity persistence. This indicates that both the four-dose and five-dose regimens are effective in maintaining long-term immunity against rabies.