Broad cross protection by recombinant live attenuated influenza H3N2 seasonal virus expressing conserved M2 extracellular domain in a chimeric hemagglutinin

Bo Ryoung Park,Noopur Bhatnagar,Yu-Jin Jung,Subbiah Jeeva,Bao-Zhong Wang,Tatiana Kotomina,Daria Mezhenskaya,Irina Isakova-Sivak,Min-Chul Kim,Young-Man Kwon,Sang-Moo Kang,Ki-Hye Kim,Larisa Rudenko

doi:10.1038/s41598-021-83704-0

Bo Ryoung Park, Noopur Bhatnagar + Show 11 more

Open Access

https://doi.org/10.1038/s41598-021-83704-0

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Abstract

Hemagglutinin (HA)-based current vaccines provide suboptimum cross protection. Influenza A virus contains an ion channel protein M2 conserved extracellular domain (M2e), a target for developing universal vaccines. Here we generated reassortant influenza virus rgH3N2 4xM2e virus (HA and NA from A/Switzerland/9715293/2013/(H3N2)) expressing chimeric 4xM2e-HA fusion proteins with 4xM2e epitopes inserted into the H3 HA N-terminus. Recombinant rgH3N2 4xM2e virus was found to retain equivalent growth kinetics as rgH3N2 in egg substrates. Intranasal single inoculation of mice with live rgH3N2 4xM2e virus was effective in priming the induction of M2e specific IgG antibody responses in mucosal and systemic sites as well as T cell responses. The rgH3N2 4xM2e primed mice were protected against a broad range of different influenza A virus subtypes including H1N1, H3N2, H5N1, H7N9, and H9N2. The findings support a new approach to improve the efficacy of current vaccine platforms by recombinant influenza virus inducing immunity to HA and cross protective M2e antigens.

Highlights

Hemagglutinin (HA)-based current vaccines provide suboptimum cross protection
Antigenic characterization by enzyme-linked immunosorbent assay (ELISA) showed that rgH3N2 4xM2e virus was highly reactive to M2 conserved extracellular domain (M2e) specific mAb 14C2 whereas rgH3N2 and A/Puerto Rico/8/1934 (A/PR8) virus controls did not show such M2e reactivity (Fig. 1b)
The results showed that rgH3N2 4xM2e virus exhibited an approximately equivalent growth kinetics in egg substrates as wild type (WT) rgH3N2 virus

Summary

Introduction

Hemagglutinin (HA)-based current vaccines provide suboptimum cross protection. Influenza A virus contains an ion channel protein M2 conserved extracellular domain (M2e), a target for developing universal vaccines. The findings support a new approach to improve the efficacy of current vaccine platforms by recombinant influenza virus inducing immunity to HA and cross protective M2e antigens. To overcome continued antigenic changes, universal vaccination strategies have been focused on inducing immunity to conserved epitopes and domains present in all influenza A viruses, including the M2 extracellular domain epitopes (M2e)[7,8] and the HA stalk d omains[9,10]. M2e-based vaccine candidates include Hepatitis B virus core protein conjugates (M2e-HBc) with adjuvants[11,12], virus-like particles (VLP) presenting M2e tandem repeats (5xM2e VLP)[13], and flagellin conjugates (4.M2e-tFliC)[14] and fusion with oligomer stabilizing domains (M2e-tGCN4)[15]. Nasal tubinates Lung rgH3N2 rgH3N2 4xM2e previous strategies inducing M2e immunity alone were insufficient for conferring optimum protection and incompatible with current vaccine platforms.

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Conclusion