A Single Dose TMV-HA Vaccine Protects Mice from H5N1 Influenza Challeng

Alison A Mccormick

doi:10.15226/2473-2176/1/2/00106

Alison A Mccormick

Open Access

https://doi.org/10.15226/2473-2176/1/2/00106

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Abstract

Recombinant subunit vaccines are an efficient strategy to meet the demands of a possible influenza pandemic, because of rapid and scalable production. However, vaccines made from recombinant Hemagglutinin (HA) subunit protein are often of low potency, requiring repeated boosting to generate a sustained immune response. Previously, we demonstrated improved immunogenicity of a plant-made H1 Hemagglutinin (HA) vaccine by chemical conjugation to the surface of the Tobacco Mosaic Virus (TMV) which is non infectious in mammals. Antigen coated TMV is taken up by mammalian dendritic cells and is a highly effective antigen carrier for subunit protein vaccines. In this work, we tested the effectiveness of a TMV-H5 HA conjugate vaccine. We compared the TMV-H5 immunogenicity in mice, with and without an oil-in water squalene adjuvant, to H5N1 virus or HA protein alone, as measured by anti-H5 IgG titers and Hemagglutination Inhibition (HAI). We then evaluated the efficacy of the TMV-H5 vaccine by lethal H5N1 virus challenge in mice. Our results show that a single dose of the TMV-H5 conjugate vaccine is sufficient to generate 40% survival, similar to H5 protein given with adjuvant, or 100% survival after vaccination with adjuvant, similar to H5N1 virus vaccination.

Highlights

Vaccination against influenza A infection has undoubtedly saved millions of lives, but zoonotic influenza represents a continuous source of potentially new infectious virus strains, either by mutation to promote human infections, or by genetic shift through reassortment with a human seasonal influenza.Since 1997, H5N1 has emerged as a potentially pandemic virus from human contact with infectious birds [1], with an alarmingly high fatality rate of ~53% [2]
Reactive agents were removed by overnight dialysis against Phosphate Buffered Saline (PBS) in Slide-a-Lyzer cartridge (Thermo-Scientific), and the protein quantity was determined by the Bicinchoninic Acid Assay (BCA;BioRad), and HA content was quantified by Enzyme Linked Immunosorbent Assay (ELISA), to normalize the vaccine dose
Vaccines were administered on day one and day 30, and sera was collected by tail vein bleed on days 14 and 28 days post vaccine 1 or day 44, 14 days post vaccine 2 for Enzyme linked Immunosorbent Assay (ELISA) analysis

Summary

Introduction

Vaccination against influenza A infection has undoubtedly saved millions of lives, but zoonotic influenza represents a continuous source of potentially new infectious virus strains, either by mutation to promote human infections, or by genetic shift through reassortment with a human seasonal influenza.Since 1997, H5N1 has emerged as a potentially pandemic virus from human contact with infectious birds [1], with an alarmingly high fatality rate of ~53% [2]. We have greatly improved the low immunogenicity of H5 HA subunit vaccination by TMV-H5 conjugation, with equivalent immune activation potency as an MF-59-like squalene adjuvant. At day 26, serum was collected for ELISA and HAI analysis, and on day 28, mice were challenged intranasally with 10xLD50 of highly pathogenic avian A/Vietnam/1203/04, diluted in 50 μL of PBS, as previously described [23].

Results

Conclusion