Immune responses elicited by influenza A mRNA vaccine based on lipopolyplex-encapsulated virus nucleoprotein and matrix protein 2 extracellular domain fusion in mice / 中华微生物学和免疫学杂志

ABSTRACT

Objective:To evaluate the immunogenicity of a novel influenza virus mRNA vaccine based on conserved antigens delivered by lipopolyplex (LPP) platform in a mouse model.Methods:Four copies of genes coding for extracellular domain of matrix 2 protein (M2e) and nucleoprotein (NP) of influenza A virus were synthetized after codon optimization. The fusion antigens were transcribed in vitro and delivered by LPP platform, named as LPP-4M2eNP. Expression of M2e and NP in eukaryotic cells was detected by immunofluorescence assay (IFA). BALB/c mice were inoculated intramuscularly twice with 10 μg or 30 μg LPP-4M2eNP vaccine at an interval of four weeks. Antibody response was detected by ELISA and cellular-mediated immunity (CMI) was detected by enzyme-linked immunospot assay (ELISPOT). Results:IFA showed that NP and M2e were expressed correctly in eukaryotic cells. Single dose immunization could induce significant antigen (NP, M2e)-specific CMI and antigen (NP, M2e)-specific antibody response was induced in mice with Th1 type bias after boost immunization. Moreover, NP-specific CMI was increased significantly after the second immunization, while no significant change in M2e-specific CMI was observed.Conclusions:Stronger CMI was triggered in mice by single dose of LPP-4M2eNP vaccine. Furthermore, robust humoral and cellular immune responses were induced after boost immunization. This study suggested that LPP-4M2eNP vaccine, which based on conserved antigen of influenza A and delivered by LPP platform, had great potential for development and application.