Preclinical evaluation of the safety and pathogenicity of a live attenuated recombinant influenza A/H7N9 seed strain and corresponding MF59-adjuvanted split vaccine

Development of MDCK-based quadrivalent split seasonal influenza virus vaccine with high safety and immunoprotection: A preclinical study

Vaccination remains the best prevention strategy against influenza. The MDCK-based influenza vaccine prompted the development of innovative cell culture manufacturing processes. In the present study, we report the effects of multiple administrations of a candidate, seasonal, MDCK-based, quadrivalent split influenza virus vaccine MDCK-QIV in Sprague-Dawley (SD) rats. Moreover, the effects of the vaccine were evaluated in terms of fertility and early embryonic development, embryo-fetal development, and perinatal toxicity in the SD rats and immunogenicity in Wistar rats and BALB/c mice. Regarding the safety profile, MDCK-QIV demonstrated tolerance in local stimulation with repeated dose administration and presented no significant effect on the development, growth, behavior, fertility, and reproductive performance of the adult male rats, maternal rats, and their offspring. MDCK-QIV elicited strong hemagglutination inhibition neutralizing antibody response and protection against the influenza virus in the mouse model. Thus, data supported that MDCK-QIV could be further evaluated in human clinical trial, which is currently underway.

Netizens' risk perception in new coronary pneumonia public health events: an analysis of spatiotemporal distribution and influencing factors

Background

Internet search volume reflects the level of Internet users’ risk perception during public health events. The Internet search volume index model, an algorithm of concentration of Internet users, and statistical analysis of popular topics on Weibo are used to analyze the effects of time, space, and space-time interaction. We conducted in-depth research on the characteristics of the spatial and temporal distribution of Internet users’ risk perceptions of public health events and the associated influential factors.

Methods

We analyzed the spatiotemporal distribution characteristics of Internet users’ risk perception after the Wuhan “city closing” order during the coronavirus disease 2019 (COVID-19) pandemic. We established five linear regression models according to different time periods and analyzed factors influencing Internet users’ risk perception by employing a Poisson and spatial distribution and topic modeling analysis.

Results

Economy, education, health, and the degree of information disclosure affect Internet users’ risk perception significantly. Internet users’ risk perception conforms to the exponential distribution law in time and has periodic characteristics and stability trends. Additionally, Internet users’ average arrival rate dropped from week 1 to week 8 after the “city closing.” Internet users’ risk perception has a uniform distribution in space, economic and social development level distribution consistency, spatial agglomeration, and other characteristics. The results of the time-space interaction show that after 8 weeks of COVID-19, Internet search hot topics have become more stable, and Internet users’ information demand structure has become more rational.

Conclusions

The Internet search cycle of the COVID-19 event is synchronized with the evolution cycle of the epidemic. The physical risk of Internet users is at the top of the risk structure, focusing on the strong concern about the government’s ability to control COVID-19 and its future trend. The government should strengthen network management; seize the risk control focus of key time nodes, regional locations, and information content of online communication; actively adjust the information content supply; effectively control the rebound of Internet users’ risk perception; establish a data-driven, risk-aware intelligence system for internet users; and guide people to actively face and overcome the potential risks and threats of COVID-19.

Immune Enhancement by the Tetra-Peptide Hydrogel as a Promising Adjuvant for an H7N9 Vaccine against Highly Pathogenic H7N9 Virus

Background: Short peptide hydrogel was reported as a possible adjuvant for vaccines. In order to evaluate whether the Tetra-Peptide Hydrogel can be a promising adjuvant for an H7N9 vaccine against the highly pathogenic H7N9 virus, we conducted this study. Methods: Tetra-Peptide Hydrogels (D and L conformations) were prepared by a self-assembly system using a Naproxen acid modified tetra peptide of GFFY (Npx-GFFY). Mice received two immunizations with the D-Tetra-Peptide Hydrogel adjuvant vaccine, the L-Tetra-Peptide Hydrogel adjuvant vaccine, or the split vaccine. Fourteen days following the second dose, the mice were challenged with the highly pathogenic A/Guangdong/GZ8H002/2017(H7N9) virus. The mice were observed for signs of illness, weight loss, pathological alterations of the lung tissues and immune responses in the following 2 weeks. Results: The D/L-Tetra-Peptide Hydrogels resembled long bars with hinges on each other, with a diameter of ~10 nm. The H7N9 vaccine was observed to adhere to the hydrogel. All the unvaccinated mice were dead by 8 days post infection with H7N9. The mice immunized by the split H7N9 vaccine were protected against infection with H7N9. Mice immunized by D/L-Tetra-Peptide Hydrogel adjuvant vaccines experienced shorter symptomatic periods and their micro-neutralization titers were higher than in the split H7N9 vaccine at 2 weeks post infection. The hemagglutinating inhibition (HI) titer in the L-Tetra-Peptide Hydrogel adjuvant vaccine group was higher than that in the split H7N9 vaccine 1 week and 2 weeks post infection. The HI titer in the D-Tetra-Peptide Hydrogel adjuvant vaccine group was higher than that in the split H7N9 vaccine at 2 weeks post infection. Conclusion: The D/L Tetra-Peptide Hydrogels increased the protection of the H7N9 vaccine and could be promising adjuvants for H7N9 vaccines against highly pathogenic H7N9 virus.

Animal Models Utilized for the Development of Influenza Virus Vaccines

Animal models have been an important tool for the development of influenza virus vaccines since the 1940s. Over the past 80 years, influenza virus vaccines have evolved into more complex formulations, including trivalent and quadrivalent inactivated vaccines, live-attenuated vaccines, and subunit vaccines. However, annual effectiveness data shows that current vaccines have varying levels of protection that range between 40–60% and must be reformulated every few years to combat antigenic drift. To address these issues, novel influenza virus vaccines are currently in development. These vaccines rely heavily on animal models to determine efficacy and immunogenicity. In this review, we describe seasonal and novel influenza virus vaccines and highlight important animal models used to develop them.

AS03-adjuvanted H7N9 inactivated split virion vaccines induce cross-reactive and protective responses in ferrets

Human infections with avian H7N9 subtype influenza viruses are a major public health concern and vaccines against H7N9 are urgently needed for pandemic preparedness. In early 2013, novel H7N9 influenza viruses emerged in China that caused about 1600 human cases of infection with a high associated case fatality rate. In this study, two H7N9 split virion vaccines with or without AS03 adjuvant were tested in the naive ferret model. Serological analyses demonstrated that homologous hemagglutination inhibition and microneutralization antibody titers were detectable in the ferrets after the first immunization with the AS03-adjuvanted vaccines that were further boosted by the second immunization. In addition, heterologous antibody titers against older H7 subtype viruses of the North American lineage (H7N7, H7N3) and newer H7 subtype viruses of the Eurasian lineage (H7N9) were detected in the animals receiving the AS03-adjuvanted vaccines. Animals receiving two immunizations of the AS03-adjuvanted vaccines were protected from weight loss and fever in the homologous challenge study and had no detectable virus in throat or lung samples. In addition, microscopic examination post-challenge showed animals immunized with the AS03-adjuvanted vaccines had the least signs of lung injury and inflammation, consistent with the greater relative efficacy of the adjuvanted vaccines. In conclusion, this study demonstrated that the AS03-adjuvanted H7N9 vaccines elicited high levels of homologous and heterologous antibodies and protected against H7N9 virus damage post-challenge.

H7N9 pandemic preparedness: A large-scale production of a split inactivated vaccine

In March 2013 it was reported by the World Health Organization (WHO) the first cases of human infections with avian influenza virus A (H7N9). From 2013 to December 2019, 1568 cases have been reported with 616 deaths. H7N9 infection has been associated with high morbidity and mortality rates, and vaccination is currently the most effective way to prevent infections and consequently flu-related severe illness. Developing and producing vaccines against pandemic influenza viruses is the main strategy for a response to a possible pandemic. This study aims to present the production of three industrial lots under current Good Manufacturing Practices (cGMP) of the active antigen used to produce the pandemic influenza vaccine candidate against A(H7N9). These batches were characterized and evaluated for quality standards and tested for immunogenicity in mice. The average yield was 173.50 ± 7.88 μg/mL of hemagglutinin and all the preparations met all the required specifications. The formulated H7N9 vaccine is poorly immunogenic and needs to be adjuvanted with an oil in water emulsion adjuvant (IB160) to achieve a best immune response, in a prime and in a boost scheme. These data are important for initial production planning and preparedness in the case of a H7N9 pandemic.

Longevity of protective immune responses induced by a split influenza A (H7N9) vaccine mixed with MF59 adjuvant in BALB/c mice

The influenza virus is a serious threat to public health worldwide. A novel avian influenza A (H7N9) virus with a mortality rate of approximately 30% has been identified as an unusually dangerous virus for humans by the World Health Organization. Pathogenic H7N9 continue to represent a public health concern, and several candidate vaccines are currently in development. We generated candidate H7N9 vaccine strains using reverse genetics, consisting of hemagglutinin and neuraminidase genes derived from a human H7N9 virus and the remaining genes from the PR8 (A/PuertoRico/8/34 (H1N1)) virus. This H7N9 vaccine exhibited superior efficacy when combined with MF59 compared to other adjuvants. Immunized BALB/c mice were followed to determine the duration of the protective immune response. Antibody levels decreased to between one-half and one-eighth of the peak values four months after the final dose of the vaccine. Previously vaccinated mice received an A/Zhejiang/DTID-ZJU01/2013 H7N9 challenge six months post-vaccination, and all remained protected. We also verified that MF59 enhanced the HI, MN, and IgG antibody titers to influenza antigens. The humoral immune response and Th2 cytokine production following influenza challenge was potently induced in the animals that received the split vaccine. Therefore, the split H7N9 influenza vaccine with the MF59 adjuvant could effectively induce antibody production and protect mice from H7N9 virus challenge even after six months.