Construction and evaluation of a universal influenza mRNA vaccine

Objective To construct a universal influenza mRNA vaccine and evaluate its immunogenicity. Methods The antigen sequence of hemagglutinin (HA), nucleoprotein (NP) and matrix protein 2 ectodomain (M2e) in influenza A/California/04/2009 was optimized.HA, NP and 3 tandem M2e (3M2e) were cloned into pcDNA3.1 vector, respectively.Then the mRNAs were synthesized by linearization, in vitro transcription, enzymatic capping and enzymatic tailing, and named as mRNA-HA, mRNA-NP and mRNA-3M2e, respectively.The protein expression of the 3 kinds of mRNAs in 293T cells was detected by immunofluorescence assay.Comb-mRNA vaccine was prepared by enveloped mRNA-HA, mRNA-NP and mRNA-3M2e with lipid nanoparticles, respectively, and the particle size and potential were identified.Twenty-eight 6-week-old female BALB/c mice (18~22 g) were randomly divided into LNP group (n=14) and Comb-mRNA group (n=14).Hemagglutination inhibition (HI) method and microneutralization (MN) test were used to evaluate the serum antibody titer induced by