mRNA Vaccines Encoding the HA Protein of Influenza A H1N1 Virus Delivered by Cationic Lipid Nanoparticles Induce Protective Immune Responses in Mice

Abstract

The design of the mRNA vaccine involves the selection of in vitro transcription (IVT) systems and nonviral delivery vectors. This study aimed to verify the effect of 5’ and 3’ untranslated region (UTR) sequences on the translation efficiency of mRNA. Three modes of IVT-mRNA systems (IVT-mRNA-n1/n2/n3) with diverse UTRs were constructed, and EGFP (enhanced green fluorescent protein) and HA (hemagglutinin) gene of H3N2 influenza virus were introduced into each of them. The results showed that the mode of 5’ and 3’ UTRs originating from human β-globulin was better than the mode of UTRs from human α-globulin, and the n3 mode was the best. mEGFP-n3, mH3HA-n3, and mLuciferease-n3 were prepared to compare the effect of cationic lipid nanoparticle (LNP) with that of mannose-conjugated LNP (LNP-Man) on the efficiency of gene delivery. The results showed that the effect of LNP-Man was better than that of LNP both in vitro and in vivo. Choosing appropriate ligands might help in vaccine design. After selecting the IVT-mRNA-n3 system and delivery vectors, mRNA vaccines were constructed against the H1N1 influenza virus, and C57BL/6 mice were immunized through intranasal administration. The results showed that mRNA vaccines could elicit both humoral and cellular immune responses and completely protect mice from the tenfold LD50 H1N1 influenza virus challenge.

Nanomaterial Delivery Systems for mRNA Vaccines

“…Once the xenograft tumor was established, 10 µg of cytokeratin 14-encoding mRNA LNPs was intranasally instilled in 100 µL PBS once per week for 3 weeks, resulting in a very significant reduction in tumor volume growth compared to the PBS control. A nucleoside-modified mRNA encoding the influenza antigen H3N2-HA was delivered in another study using DOTAP/DOPE/PEG–lipid LNPs, as well as in the same LNP-bearing mannose as a ligand to facilitate uptake by macrophages and dendritic cells [ 130 ]. These LNPs were also large, at 200 nm, positively charged, at 15 mV zeta potential, and able to express luciferase in the lungs following intranasal instillation of a 12 µg dose.…”

Self-assembled mRNA vaccines

“…mRNA vaccines administered to the mucosal layers, such as the nasal and pulmonary mucosa, travel to the draining mucosal LNs via lymphatic systems under the epithelium [ 86 , 110 , 111 ]. Particularly, prophylactic mRNA therapeutics to prevent respiratory diseases, such as influenza [ 112 ] and RSV [ 83 ], are preferred to be delivered via intranasal (IN) administration [ 113 ] because mucosal vaccination can offer pathogen-specific antibodies to be secreted to the mucus where the antibodies can neutralize the pathogens at the early stage of infection [ 114 ]. Additionally, mucosal delivery of mRNA vaccines can cause the secretion of immunoglobulin A (IgA).…”

Promising Adjuvants and Platforms for Influenza Vaccine Development

“…Full-length influenza HA mRNA-encapsulated LNPs induced HA-stalk-specific antibodies that provided cross-protection in mice [ 89 ]. Meanwhile, intradermal (ID) delivery of combined influenza HA stalk, neuraminidase (NA), matrix-2 ion channel (M2), and NP mRNA LNPs have induced robust immune responses and provided broad protection [ 89 , 90 , 91 , 92 ]. Thus, codelivery of appropriate adjuvants with the mRNA LNPs is an effective method to enhance the immune response.…”