A Y161F Hemagglutinin Substitution Increases Thermostability and Improves Yields of 2009 H1N1 Influenza A Virus in Cells

Abstract

Vaccination is the primary strategy for influenza prevention and control. However, egg-based vaccines, the predominant production platform, have several disadvantages, including the emergence of viral antigenic variants that can be induced during egg passage. These limitations have prompted the development of cell-based vaccines, which themselves are not without issue. Most importantly, vaccine seed viruses often do not grow efficiently in mammalian cell lines. Here we aimed to identify novel high-yield signatures for influenza viruses in continuous Madin-Darby canine kidney (MDCK) and Vero cells. Using influenza A(H1N1)pdm09 virus as the testing platform and an integrating error-prone PCR-based mutagenesis strategy, we identified a Y161F mutation in hemagglutinin (HA) that not only enhanced the infectivity of the resultant virus by more than 300-fold but also increased its thermostability without changing its original antigenic properties. The vaccine produced from the Y161F mutant fully protected mice against lethal challenge with wild-type A(H1N1)pdm09. Compared with A(H1N1)pdm09, the Y161F mutant had significantly higher avidity for avian-like and human-like receptor analogs. Of note, the introduction of the Y161F mutation into HA of seasonal H3N2 influenza A virus (IAV) and canine H3N8 IAV also increased yields and thermostability in MDCK cells and chicken embryotic eggs. Thus, residue F161 plays an important role in determining viral growth and thermostability, which could be harnessed to optimize IAV vaccine seed viruses. Although a promising complement to current egg-based influenza vaccines, cell-based vaccines have one large challenge: high-yield vaccine seeds for production. In this study, we identified a molecular signature, Y161F, in hemagglutinin (HA) that resulted in increased virus growth in Madin-Darby canine kidney and Vero cells, two cell lines commonly used for influenza vaccine manufacturing. This Y161F mutation not only increased HA thermostability but also enhanced its binding affinity for α2,6- and α2,3-linked Neu5Ac. These results suggest that a vaccine strain bearing the Y161F mutation in HA could potentially increase vaccine yields in mammalian cell culture systems.

N -Glycolylneuraminic Acid Binding of Avian and Equine H7 Influenza A Viruses

“…2F ). In the 150-loop, a highly conserved tyrosine is present at position 161 in all HA subtypes except H7, H10, H12, H15, H17, and H18 ( 25 , 30 , 31 ). Previously, it was demonstrated that a Y161A mutation changed the binding properties of an H5 HA from NeuAc to NeuGc ( 17 , 30 ).…”

Mutation W222L at the Receptor Binding Site of Hemagglutinin Could Facilitate Viral Adaption from Equine Influenza A(H3N8) Virus to Dogs

“…N-glycan isoform microarray. The 83 N-glycans (41) were printed on N-hydroxysuccinimide (NHS)derivatized slides as described previously (42). All glycans were printed in replicates of six in a subarray, and eight subarrays were printed on each slide.…”

Tissue tropisms opt for transmissible reassortants during avian and swine influenza A virus co-infection in swine

“…Two biotinlyated glycan analogs, 3ʹSLN and 6ʹSLN, were purchased from GlycoTech (Gaithersburg, MD, USA). Binding of viruses (at 5 nM/virus) to the biotinylated glycan analogs was performed as previously described [64] in an Octet RED96 biolayer interferometer equipped with streptavidin biosensor tips (PALL FortéBIO, Menlo Park, CA, USA). The glycan concentrations ranged from 0.007 μg/mL to 1.5 μg/mL.…”