Abstract
Vaccination is the most effective course of action to prevent influenza. About 150 million doses of influenza vaccines were distributed for the 2015–2016 season in the USA alone according to the Centers for Disease Control and Prevention. Vaccine dosage is calculated based on the concentration of hemagglutinin (HA), the main surface glycoprotein expressed by influenza which varies from strain to strain. Therefore yearly-updated strain-specific antibodies and calibrating antigens are required. Preparing these quantification reagents can take up to three months and significantly slows down the release of new vaccine lots. Therefore, to circumvent the need for strain-specific sera, two anti-HA monoclonal antibodies (mAbs) against a highly conserved sequence have been produced by immunizing mice with a novel peptide-conjugate. Immunoblots demonstrate that 40 strains of influenza encompassing HA subtypes H1 to H13, as well as B strains from the Yamagata and Victoria lineage were detected when the two mAbs are combined to from a pan-HA mAb cocktail. Quantification using this pan-HA mAbs cocktail was achieved in a dot blot assay and results correlated with concentrations measured in a hemagglutination assay with a coefficient of correlation of 0.80. A competitive ELISA was also optimised with purified viral-like particles. Regardless of the quantification method used, pan-HA antibodies can be employed to accelerate process development when strain-specific antibodies are not available, and represent a valuable tool in case of pandemics. These antibodies were also expressed in CHO cells to facilitate large-scale production using bioreactor technologies which might be required to meet industrial needs for quantification reagents. Finally, a simulation model was created to predict the binding affinity of the two anti-HA antibodies to the amino acids composing the highly conserved epitope; different probabilities of interaction between a given amino acid and the antibodies might explain the affinity of each antibody against different influenza strains.
Highlights
Influenza is a contagious disease that can lead to hospitalization, and even death for vulnerable patients
The panel of strains tested include viruses produced in eggs and mammalian cells, Viral-like particles (VLPs) produced in plants and recombinant HA proteins
The signal measured for H1N1/A/California/07/ 2009 virus preparations varied from low to high when produced in avian cells versus eggs, even though similar concentrations were tested
Summary
Influenza is a contagious disease that can lead to hospitalization, and even death for vulnerable patients. The influenza virus belongs to the Orthomyxoviridae family and is classified as type A, B or C. Disease prevention is achieved through vaccination, and the production of vaccine lots is initiated several months before the flu season based on predictions. New strains of influenza emerge every few years and lead to a mismatch between the predicted vaccine strains and the circulating strains, which can significantly decrease the efficacy of the vaccine. Sixty percent of influenza vaccines are still produced by inoculating fertilized eggs, but new production platforms have been reported or are being used such as insect-cell cultures [3], other mammalian cell lines [4,5,6,7,8,9] as well as plantbased vaccines [10,11,12,13]
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