Development and Evaluation of Vero Cell-Derived Master Donor Viruses for Influenza Pandemic Preparedness

Vaccine optimization for highly pathogenic avian influenza: Assessment of antibody responses and protection for virus-like particle vaccines in chickens

Background

Recent outbreaks of clade 2.3.4.4b highly pathogenic avian influenza (HPAI) H5N1 viruses in regions previously less affected since 2020 have raised global concerns. Implementing mass immunization or ring vaccination in poultry should be a countermeasure ready to contain disease outbreaks. This study focuses on developing a recombinant H5N2 vaccine based on virus-like particles (VLPs) against clade 2.3.4.4c, the predominant HPAI subclade in Taiwan since its emergence, leading to a large outbreak in 2015.

Methods

The study aimed to confirm the effectiveness of clade 2.3.4.4c H5N2 VLPs in protecting chickens and identify the best adjuvants for the VLP vaccine. We used Montanide 71VG-adjuvanted inactivated RG6 to establish the immunization protocol, followed by prime-boost H5N2-VLP immunizations. We compared adjuvants: 71VG, 71VG with VP3, and Alum with VP3. Serum samples were tested for antibodies against homologous vaccine antigens and cross-clade antigens by hemagglutination inhibition (HI) assays. Finally, we evaluated the protective efficacy by lethally challenging immunized chickens with H5 viruses from clade 1 or 2.3.4.4c.

Results

Poultry adjuvant 71VG significantly enhanced antibody responses in chickens with inactivated RG6 compared to unadjuvanted inactivated virus. While increasing antigen dosage enhanced 71VG adjuvanted RG6-induced antibody titers, the vaccine displayed minimal cross-reactivity against locally circulating HPAI H5N2. In contrast, H5N2-VLP containing the HA protein of clade 2.3.4.4c, adjuvanted with (FMDV) VP3 in 71VG, significantly promoted HI antibody responses. All H5N2-VLP immunized chickens survived lethal challenges with the local clade 2.3.4.4c H5 strain.

Conclusion

The study demonstrated the immunogenic potential of the VLP vaccine in chickens. Our findings offer insights for optimizing VLP vaccines, allowing the incorporation of the HA of currently circulating H5 viruses to effectively mitigate the impact of the rapidly evolving clade 2.3.4.4 H5 outbreaks.

A novel N95 respirator with chitosan nanoparticles: mechanical, antiviral, microbiological and cytotoxicity evaluations

BACKGROUND

It is known that some sectors of hospitals have high bacteria and virus loads that can remain as aerosols in the air and represent a significant health threat for patients and mainly professionals that work in the place daily. Therefore, the need for a respirator able to improve the filtration barrier of N95 masks and even inactivating airborne virus and bacteria becomes apparent. Such a fact motivated the creation of a new N95 respirator which employs chitosan nanoparticles on its intermediate layer (SN95 + CNP).

RESULTS

The average chitosan nanoparticle size obtained was 165.20 ± 35.00 nm, with a polydispersity index of 0.36 ± 0.03 and a zeta potential of 47.50 ± 1.70 mV. Mechanical tests demonstrate that the SN95 + CNP respirator is more resistant and meets the safety requisites of aerosol penetration, resistance to breath and flammability, presenting higher potential to filtrate microbial and viral particles when compared to conventional SN95 respirators. Furthermore, biological in vitro tests on bacteria, fungi and mammalian cell lines (HaCat, Vero E6 and CCL-81) corroborate the hypothesis that our SN95 + CNP respirator presents strong antimicrobial activity and is safe for human use. There was a reduction of 96.83% of the alphacoronavirus virus and 99% of H1N1 virus and MHV-3 betacoronavirus after 120 min of contact compared to the conventional respirator (SN95), demonstrating that SN95 + CNP have a relevant potential as personal protection equipment.

CONCLUSIONS

Due to chitosan nanotechnology, our novel N95 respirator presents improved mechanical, antimicrobial and antiviral characteristics.

Membrane Chromatography-Based Downstream Processing for Cell-Culture Produced Influenza Vaccines

New influenza strains are constantly emerging, causing seasonal epidemics and raising concerns to the risk of a new global pandemic. Since vaccination is an effective method to prevent the spread of the disease and reduce its severity, the development of robust bioprocesses for producing pandemic influenza vaccines is exceptionally important. Herein, a membrane chromatography-based downstream processing platform with a demonstrated industrial application potential was established. Cell culture-derived influenza virus H1N1/A/PR/8/34 was harvested from benchtop bioreactor cultures. For the clarification of the cell culture broth, a depth filtration was selected as an alternative to centrifugation. After inactivation, an anion exchange chromatography membrane was used for viral capture and further processing. Additionally, two pandemic influenza virus strains, the H7N9 subtype of the A/Anhui/1/2013 and H3N2/A/Hong Kong/8/64, were successfully processed through similar downstream process steps establishing optimized process parameters. Overall, 41.3–62.5% viral recovery was achieved, with the removal of 86.3–96.5% host cell DNA and 95.5–99.7% of proteins. The proposed membrane chromatography purification is a scalable and generic method for the processing of different influenza strains and is a promising alternative to the current industrial purification of influenza vaccines based on ultracentrifugation methodologies.