Immunogenicity and Protection of Influenza A Virus H1N1 Hemagglutinin Stem Subunit Vaccine Combined with Different Adjuvants in Mice
The influenza virus hemagglutinin stem region(Mini-HA)was produced using a eukaryotic expression system,then co-immunized with different adjuvants in mice to evaluate its immunogenicity and protective efficacy.Plasmid pcDNA3.1-MiniHA(H1)was constructed using the target gene sequence of the HA stem region from A/Brisbane/59/2007(H1N1)with codon optimization and structural modification.HEK-293T cells were transfected with the plasmid,and Mini-HA protein was purified from the culture supernatant using nickel affinity chromatography.Mice were co-immunized with Mini-HA and three different adjuvants,namely Al(OH)3,Al(OH)3+CPG ODN,and AddaS03TM.Humoral and cellular immune responses were assessed through ELISA,ELISPOT,and ICS.Furthermore,protective efficacy was evaluated through challenge experiments with A/PR/8/34(H1N1),monitoring survival rates,body weight changes,lung virus titers,and lung histopathological alterations.The results revealed that specific IgG antibodies against both the HA stem region and the full-length HA were detected after the initial immunization,and antibody titers significantly increased following booster immunizations.Mini-HA combined with Al(OH)3+CPG ODN stimulated the secretion of Th1-type cytokines,while combined with AddaS03TM induced both Th1 and Th2-type cytokine secretion.In the challenge experiments,mice co-immunized with Mini-HA and either A1(OH)3+CPG ODN or AddaS03TM adjuvants provided 100％protection from lethal challenge,with less than a 5％mean weight loss.Specifically,co-immunization with Mini-HA and AddaS03TM exhibited intact lung tissue structure,with only minor compensatory alveolar dilation and a small amount inflammatory cell infiltration.In this study,the HA stem protein Mini-HA was successfully purified and formed a trimer structure.Mice immunized with Mini-HA combined with adjuvant had good immunogenicity,and AddaS03TM adjuvant had the best effect,which could induce specific humoral and cellular immune responses,protect mice against the attack of H1N1 PR8,effectively inhibit virus replication,and reduce pathological damage to lung tissue.
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