Flu News Friday 6/4/21
Read the latest on influenza vaccines in this week’s roundup.
The Latest in Influenza Vaccines
Conference Announcement: The Eighth ESWI Influenza Conference is December 4th to 7th, 2021. Join colleagues and peers from around the world in Salzburg for the largest conference dedicated to influenza, RSV disease and Covid-19. Register here. Abstracts are due September 3, 2021; submit abstracts here.
1. First exposure to the pandemic H1N1 virus induced broadly neutralizing antibodies targeting hemagglutinin head epitopes
Guthmiller et al., Science Translational Medicine / June 2, 2021
Broadly neutralizing antibodies are critical for protection against antigenically drifted and shifted influenza strains; these antibodies target conserved portions of the virus. Scientists analyzed B cells targeting the hemagglutinin (HA) head after vaccination. This study found that first exposure to pandemic H1N1 (pN1N1) preferentially recruits memory B cells targeting two conserved epitopes on the HA head domain: the receptor-binding and lateral patch sites. Mice receiving these receptor-binding- and lateral patch-specific antibodies were protected from lethal influenza infection. However, it was found preexisting immunity against variable epitopes of the HA head limits recruitment of memory B cells against conserved head epitopes. Scientists conclude future universal influenza vaccine strategies should focus on eliciting antibodies against both the conserved head and stalk domains.
2. A pandemic upside: The flu virus became less diverse, simplifying the task of making flu shots
Helen Branswell, STAT / June 2, 2021
The COVID-19 pandemic brought social distancing and travel restrictions, driving influenza activity to historically low levels globally. It appears the global “pool” of circulating influenza viruses has decreased, in both A and B lineages. STAT discusses why these COVID-19 non-pharmaceutical interventions reduced the diversity of influenza.
3. NIH launches clinical trial of universal influenza vaccine candidate
National Institutes of Health / June 1, 2021
The NIH has launched a phase I clinical trial of a universal influenza vaccine (FluMos-v1) candidate to test the safety and immunogenicity of the UIV in humans, compared to a cell-based seasonal influenza vaccine (Flucelvax). The mosaic nanoparticle vaccine, designed through a collaboration between the National Institute of Allergy & Infectious Diseases (NIAID) and the University of Washington Institute for Protein Design, is comprised of 20 HA ectodomain trimers from two influenza A strains and two influenza B strains.
4. A liposome-displayed hemagglutinin vaccine platform protects mice and ferrets from heterologous influenza virus challenge
Sia et al., Proceedings of the National Academies of Sciences / June 1, 2021
Scientists develop a lipo-nanoparticle influenza vaccine displaying HA antigens. The liposome adjuvant design led to enhanced immunogenicity of the HA particles. Vaccinated mice and ferrets were protected from heterologous influenza challenge. The vaccine also exhibited a dose-sparing effect, meaning that a smaller dose was needed to elicit protection compared to typical vaccines. The findings have implications for the development of future pandemic and broadly protective influenza vaccines.
5. The missing season: The impacts of the COVID-19 pandemic on influenza
Zipfel et al., May 30, 2021
Scientists discuss the potential factors for the suppression of the 2020–2021 influenza season, focusing on France, The United States and Australia. They propose that the most influential process were the significant behavioral interventions — non-pharmaceutical interventions — implemented for the COVID-19 pandemic. Lessons learned from this past influenza season regarding influenza dynamics and control should inform future control of respiratory diseases, particularly for the 2021–2022 influenza season.
6. Changes in sialic acid binding associated with egg adaptation decrease live attenuated influenza virus replication in human nasal epithelial cell cultures
Powell et al., Vaccine / May 10, 2021
Live attenuated influenza vaccines (LAIV) are administered and replicate in the nasal epithelium. Both inactivated influenza vaccines (IIV) and LAIVs are selected and grown in eggs; this process can lead to undesired adaptive mutations in the HA protein, leading to vaccine strains mismatched with the desired selected strains and lower vaccine efficacy. Scientists determined these mutations may also adversely affect LAIV replication and dampen innate immune responses, playing a role in reduced vaccine efficacy.
7. Design of the recombinant influenza neuraminidase antigen is crucial for protective efficacy [Pre-Print]
Gao et al., bioRxiv / April 30, 2021
In this preprint, researchers analyze several recombinant neuraminidase antigens (rNAs) produced from different construct designs. The study examines and compares enzymatic properties, antigenicity, thermal and size stability, and immune responses and protection elicited by the different rNAs in a mouse model. Construct designs include rNA with the full ectodomain (the head, stalk, and transmembrane domains) and an rNA with the head domain and tetramerization motif added. The findings provide insights for incorporating rNAs into future influenza vaccines.
8. Funding Opportunities & Announcements
A Refresher on Application Resubmission Strategy
National Institute of Allergy & Infectious Diseases Funding News / June 2, 2021