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.

Background/Objectives: Acne vulgaris is a chronic inflammatory skin disorder characterized by sebaceous gland hyperactivity, follicular hyperkeratinization, proliferation of Cutibacterium acnes (C. acnes), and subsequent inflammation. The development of effective therapeutics necessitates reliable preclinical models that accurately replicate key pathological aspects of the human disease. Methods: In this study, we established an inflammatory acne model in Wistar rats via the intradermal injection of live C. acnes into the ear pinnae and thoroughly characterized its temporal dynamics of the induced inflammation. Utilizing this model, we evaluated the protective efficacy of a whole-cell inactivated C. acnes vaccine (HI-C. acnes) formulated with adjuvants WS03 or MA107b. Results: Inflammation peaked between days 1 and 3 post-infection, manifesting as pronounced erythema, ear swelling, increased ear thickness, elevated bacterial load, and significant upregulation of pro-inflammatory cytokines (IL-6, IL-1β, and MCP-1). Histopathological examination revealed extensive neutrophil infiltration and microabscess formation, while immunohistochemistry confirmed localized overexpression of TNF-α, IL-1β, and CXCL1 within the lesional tissue. Inflammatory manifestations gradually subsided by day 5 and were fully resolved by day 7, which coincided with complete bacteria clearance and normalization of pro-inflammatory cytokine levels. Vaccinated rats developed significantly higher C. acnes-specific IgG titers and, upon challenge, exhibited markedly reduced ear swelling, diminished bacterial burden, and suppressed expression of key inflammatory mediators compared to control groups, indicating that vaccine-induced protection is associated with humoral immunity. Conclusions: Collectively, our standardized and quantifiable rat ear inflammation model provides a robust platform for mechanistic investigations and preclinical assessment of novel anti-acne vaccines and therapeutic agents.

Background: Inactivated enterovirus 71 (EV71) vaccines play a vital role in preventing severe cases of hand, foot, and mouth disease, with their quality and stability determined by the degree of viral particle aggregation. Objective: This study aimed to use dynamic light scattering (DLS) for monitoring EV71 particle size, comprehensively evaluate the effects of environmental stresses on viral aggregation, and identify suitable stabilizing agents. Methods: The DLS technique was validated. Using this method, the effects of pH, ionic strength, freeze–thaw cycles, temperature, and mechanical stresses on viral particle size were assessed. Additionally, the ability of different buffer salts and stabilizers to inhibit stress-induced aggregation was systematically evaluated. Results: The DLS method exhibited robust performance. EV71 particles were stable at pH 7.0–7.5. Exposure to 47 °C and magnetic stirring promoted viral aggregation. Phosphate buffer and citrate buffer exhibited the highest inhibitory effects on heat-induced aggregation and stirring-induced aggregation, respectively. M199 and Tween 80 efficiently mitigated heat-induced particle aggregation and shear stress-induced particle aggregation, respectively. Conclusions: This study demonstrated the performance of DLS in viral aggregation monitoring. Additionally, this study revealed tailored stabilization strategies, providing key insights for vaccine formulation and quality control.

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.