Thermostable vacuum foam dried Newcastle disease vaccine: Process optimization and pilot-scale study.

Vacuum foam drying (VFD) has been shown to improve the thermostability and long-term shelf life of Newcastle Disease Virus (NDV). This study optimized the VFD process to improve the shelf life of NDV at laboratory-scale and then tested the optimized conditions at pilot-scale. The optimal NDV to T5 formulation ratio was determined to be 1:1 or 3:2. Using the 1:1 virus to formulation ratio, the optimal filling volumes were determined to be 13-17% of the vial capacity. The optimized VFD process conditions were determined to be at a shelf temperature of 25℃ with a minimum overall drying time of 44 h. The vaccine samples prepared using these optimized conditions at laboratory-scale exhibited virus titer losses of ≤ 1.0 log10 with residual moisture content (RMC) below 3%. Furthermore, these samples were transported for 97 days around China at ambient temperature without significant titer loss, thus demonstrating the thermostability of the NDV-VFD vaccine. Pilot-scale testing of the NDV-VFD vaccine at optimized conditions showed promising results for up-scaling the process as the RMC was below 3%. However, the virus titer loss was slightly above 1.0 log10 (approximately 1.1 log10). Therefore, the NDV-VFD process requires further optimization at pilot scale to obtain a titer loss of ≤ 1.0 log10. Results from this study provide important guidance for possible industrialization of NDV-VFD vaccine in the future. KEY POINTS: • The process optimization and scale-up test of thermostable NDV vaccine prepared through VFD is reported for the first time in this study. • The live attenuated NDV-VFD vaccine maintained thermostability for 97 days during long distance transportation in summer without cold chain conditions. • The optimized NDV-VFD vaccine preparations evaluated at pilot-scale maintained acceptable levels of infectivity after preservation at 37℃ for 90 days, which demonstrated the feasibility of the vaccine for industrialization.

Zr(IV)-based metal-organic framework nanocomposites with enhanced peroxidase-like activity as a colorimetric sensing platform for sensitive detection of hydrogen peroxide and phenol.

Recently, metal-organic frameworks (MOFs) have great potential as an emerging peroxide-mimicking enzyme, and the improvement of its enzyme-like activity is desired. There are few studies on improving the peroxidase-like activity of MOFs by using the strategy of size reduction. Moreover, it is challenging to enhance the activity of Zr-based MOFs with peroxidase-mimicking activity by size reduction strategy. In this work, the synthesis of Zr-based MOFs capped with polyvinylpyrrolidone (Zr-MOF-PVP) was firstly reported to reduce crystal size of peroxidase-mimicking enzyme for enhanced catalytic activity. Using the 3,3',5,5'-Tetramethylbenzidine (TMB) as substrate, the synthesized Zr-MOF-PVP nanocomposites with nanosize (about 45 nm) possessed obviously enhanced peroxidase-like activity compared with the pristine Zr-MOF. Based on the above, the Zr-MOF-PVP was also successfully applied in constructing colorimetric detection. By using hydrogen peroxide (H2O2) and phenol as the model analytes, the satisfactory detection performance was obtained, indicating that the proposed method had an attractive application prospect in the field of peroxidase-related detection. Besides, this work also provided a new perspective for improving the catalytic activity of nanozymes.

Synergetic integration of catalase and Fe3O4 magnetic nanoparticles with metal organic framework for colorimetric detection of phenol.

Toxic phenol pollutants pose a great threat to the environment, it is urgent to develop an efficient and recyclable method to monitor phenol. Herein, we reported the synthesis of catalase-Fe3O4@ZIF-8 (CAT-Fe3O4@ZIF-8) through a novel amino-acid-boosted one-pot embedding strategy that synergically integrated catalase and magnetic Fe3O4 nanoparticles with ZIF-8. As expected, CAT-Fe3O4@ZIF-8 exhibited enhanced catalytic activity compared with Fe3O4@ZIF-8, CAT@ZIF-8 and catalase. Depending on the satisfactory performance of CAT-Fe3O4@ZIF-8, a colorimetric detection platform for phenol based on CAT-Fe3O4@ZIF-8 was constructed. The corresponding detection limit was as low as 0.7 µM, and a wide linear range of 5-100 µM was obtained. Besides, CAT-Fe3O4@ZIF-8-based colorimetric detection platform has been verified to possess high stability and recyclability. The proposed method was proven to have potential practical applications in the field of water treatment, which would advance efficient, recyclable monitoring of water quality.

Vacuum Foam Drying Method Improved the Thermal Stability and Long-Term Shelf Life of a Live Attenuated Newcastle Disease Virus Vaccine.

Vaccines used for managing Newcastle disease virus (NDV) rely heavily on cold chain, and this results in major constraints in their successful application, shipping, and storage. This study was undertaken to improve the thermotolerance properties of live attenuated NDV vaccines using vacuum foam drying (VFD) technology. The live attenuated NDV vaccine formulated in 15% trehalose, 2.5% gelatin, 0.05% pluronic, and 25 mmol/L potassium phosphate buffer (T5) and dried using VFD showed improved heat tolerance in comparison to the vaccine formulated in T5 as well, but dried using freeze-drying (FD) method. The T5-formulated VFD vaccine was stored at 37°C for 120 days, 45°C for 7 days, and 60°C for 3 days; the virus titer loss decreased by no more than 1.0 Log10. In contrast, the FD vaccine prepared in T5 could only be stored at 37°C for 7-10 days. Furthermore, the T5-formulated NDV-VFD vaccine remained infectious when heated at 100°C for 30 min. Shelf-life studies confirmed the improved thermal tolerance of the T5-formulated NDV-VFD vaccine since it could be stably stored at 2-8°C for 42 months and 25°C for 15 months. Moreover, immunization of 1-month-old specific pathogen-free (SPF) chickens with the T5-formulated NDV-VFD vaccine stored at 25 and 37°C could produce hemagglutination inhibition (HI) antibody levels comparable to those of commercial NDV-FD vaccines, which require strict adherence to the cold chain. In conclusion, not only did the VFD technology improve the thermostability and long-term shelf life of the vaccine, it also maintained its immunogenicity.

Alginate di-aldehyde-modified metal-organic framework nanocarriers as delivery platform and adjuvant in inactivated pseudorabies vaccination.

Pseudorabies virus (PRV) is a highly contagious viral disease, which leads to severe financial losses in the breeding industry worldwide. Presently, PRV is mainly controlled using live attenuated and inactivated vaccines. However, these vaccines have an innate tendency to lose their structural conformation upon exposure to environmental and chemical stressors and cannot provide full protection against the emerging prevalent PRV variants. In this work, first, we synthesized aminated ZIF-7/8 nanoparticles (NPs), and then chemical bond-coated alginate dialdehyde (ADA, a type of dioxide alginate saccharide) on their surface via Schiff base reaction to obtain ZIF-7/8-ADA NPs. The as-fabricated ZIF-7/8-ADA NPs exhibited high stability, monodispersity and a high loading ratio of antigen. Furthermore, the ZIF-7/8-ADA NPs showed good biocompatibility in vitro and in vivo. Using ZIF-7/8-ADA NPs as an adjuvant and inactivated PRV as a model antigen, we constructed a PR vaccine through a simple mixture. The immunity studies indicated that ZIF-7/8-ADA induced an enhancement in the Th1/Th2 immune response, which was superior to that of the commercial ISA201, alum adjuvant and ZIF-7/8. Due to the pH-sensitive release of the antigen in lysosomes, the as-prepared PR vaccine subsequently accelerated the antigen presentation and improved the immune responses in vitro and in vivo. The results of PRV challenge using mice as the model demonstrated that ZIF-7/8-ADA achieved the same preventive effect as the commercial ISA201 and was much better than the alum adjuvant, and thus can serve as a promising delivery system and adjuvant to enhance humoral and cellular responses against PRV infection.

Optimization of Heat-Resistance Technology for a Duck Hepatitis Lyophilized Live Vaccine.

In this study, to improve the quality of a live attenuated vaccine for duck viral hepatitis (DHV), the lyophilization of a heat-resistant duck hepatitis virus vaccine was optimized. The optimized heat protectors were made of 10% sucrose, 1.2% pullulan, 0.5% PVP, and 1% arginine, etc., with a titer freeze-drying loss of ≤0.50 Lg. The vaccine product's valence measurements demonstrated the following: the vaccine could be stored at 2-8 °C for 18 months with a virus titer loss ≤0.91 Lg; at 37 °C for 10 days with a virus valence loss ≤0.89 Lg; and at 45 °C for 3 days with a virus titer loss ≤0.90 Lg. Regarding safety, no deaths occurred in two-day-old ducklings immunized with a 10 times dose vaccine; their energy, diet, and weight gain were all normal, demonstrating that the DHV heat-resistant vaccines were safe for ducklings and did not cause any immune side effects. Duck viral hepatitis freeze-dried vaccine began to produce antibodies at 7 d after immunization, reached above 5.0 on 14 d, and reached above 7.0 on 21 d, showing a continuous upward trend. This indicates that duck viral hepatitis vaccine has a good immunogen level. The optimization of the freeze-drying process saves costs and also improves the quality of the freeze-drying products, which provides important theoretical and technical support for the further study of vaccine products.

Development of a water-in-oil-in-water adjuvant for foot-and-mouth disease vaccine based on ginseng stem-leaf saponins as an immune booster.

There has been an increasing interest in finding new formulations that qualify as vaccine adjuvants, which must be safe, stable, and have the capacity to stimulate a strong immune response. In this study, a basic formulation of a water-in-oil-in-water (W/O/W) adjuvant CV13 was developed, and ginseng stem-leaf saponins (GSLS) were added as an immune booster into oil phase. The physicochemical properties of the adjuvant were tested. Furthermore, the immune activity and the adjuvant effects, as indicated by the foot-and-mouth disease virus (FMDV) antigen were evaluated. The results showed that CV13 was similar in appearance to ISA 206 and could package FMDV antigen into a stable W/O/W emulsion. The FMD vaccine prepared with CV13 alone or CV13 containing GSLS achieved pharmaceutical characteristics comparable to a vaccine prepared with ISA 206, moreover the structural stability of the CV 13 vaccine was found to be better. Mice that were immunized with the FMD vaccine prepared with CV13 containing GSLS presented a significantly higher LPBE antibody titer and splenocyte proliferation rate than those immunized with a vaccine prepared with CV13 alone (p < 0.05). In addition, there was no significant difference between the groups that were immunized with FMD vaccine prepared with CV13 containing GSLS and ISA206 in terms of cellular and humoral immune response. In this paper, CV13 containing GSLS shows excellent immunologic adjuvant effect in mice model, and this new adjuvant may provide a potential choice for FMD vaccine production in the future.

Live vaccine preserved at room temperature: Preparation and characterization of a freeze-dried classical swine fever virus vaccine.

The heat-stable live-attenuated classical swine fever virus (CSFV) vaccine is an urgent need in many countries of Asia, Europe and Latin America. In this study, the thermostability of lyophilized live-attenuated CSFV vaccine formulations were investigated using accelerated stability at 37 °C for 10 days. The freeze-dried heat-stable formulation ST16, containing excipient combinations of trehalose, glycine, thiourea and phosphate buffer shows the superior thermostability. Moreover, the lyophilized vaccine with formula ST16 kept loss of viral activity less than 0.5 log10 during 24 months at storage temperatures of 2-8 °C. In thermal study, ST16 stabilized the vaccine within 1.0 log10 loss after storage at up to 25 °C for 6 months and room temperature for 7 months. Even under the harshest storage conditions of 37 °C for 25 days and 45 °C for 2 weeks, the virus titer dropped less than 1.0 log10 using ST16. Besides, it is notable that ST16 excluded gelatin and exogenous proteins, which might cause allergic reactions, thus avoiding immune side effects. The vaccine formulated ST16 proved to be safe and effective when immunized to piglets in vivo. The characteristics of dried vaccines were analyzed by X-ray powder diffraction, residual water measurements, differential scanning calorimetry and it was found that vaccine antigen were preserved in an amorphous matrix with high glass transition temperature above 60 °C and low residual water content below 2%, which made the vaccine more stable during storage.