Current influenza vaccines provide hemagglutinin (HA) strain-specific protection. To improve cross protection, we engineered replication-competent influenza A virus to express tandem repeats of heterologous M2 extracellular (M2e) domains in a chimeric HA. M2e epitopes conjugated to HA glycoproteins (M2e4x-HA) were found to be expressed on the surfaces of a replicable influenza virus as examined by electron microscopy. The recombinant influenza virus containing M2e4x-HA was moderately attenuated but superior to the parental virus in inducing M2e specific antibodies without compromising HA immunogenicity. Recombinant influenza virus immune mice showed better cross protection than parental virus immune mice. Immune sera from the mice with inoculation of live recombinant influenza virus expressing M2e4x-HA were effective in conferring protection against H1, H3, and H5 subtype influenza viruses. This study indicates that recombinant influenza virus expressing conserved protective epitopes in an HA chimeric form can provide a new approach for improving the efficacy of influenza vaccines.

当前的流感疫苗提供血凝素（HA）菌株特异性保护。为了改善交叉保护，我们设计了具有复制能力的甲型流感病毒，以在嵌合HA中表达异源M2细胞外（M2e）域的串联重复序列。通过电子显微镜检查，发现与HA糖蛋白（M2e4x-HA）缀合的M2e表位在可复制的流感病毒的表面上表达。含有M2e4x-HA的重组流感病毒在诱导M2e特异性抗体而不损害HA免疫原性的过程中被适度减毒，但优于亲本病毒。重组流感病毒免疫小鼠显示出比亲代病毒免疫小鼠更好的交叉保护。接种表达M2e4x-HA的活重组流感病毒的小鼠的免疫血清可有效保护H1，H3和H5亚型流感病毒。这项研究表明，重组流感病毒以HA嵌合体形式表达保守的保护性抗原决定簇可以为提高流感疫苗的效力提供一种新方法。