Virus-like Particles Containing Multiple M2 Extracellular Domains Confer Improved Cross-protection Against Various Subtypes of Influenza Virus

Abstract

The extracellular domain of M2 (M2e), a small ion channel membrane protein, is well conserved among different human influenza A virus strains. To improve the protective efficacy of M2e vaccines, we genetically engineered a tandem repeat of M2e epitope sequences (M2e5x) of human, swine, and avian origin influenza A viruses, which was expressed in a membrane-anchored form and incorporated in virus-like particles (VLPs). The M2e5x protein with the transmembrane domain of hemagglutinin (HA) was effectively incorporated into VLPs at a several 100-fold higher level than that on influenza virions. Intramuscular immunization with M2e5x VLP vaccines was highly effective in inducing M2e-specific antibodies reactive to different influenza viruses, mucosal and systemic immune responses, and cross-protection regardless of influenza virus subtypes in the absence of adjuvant. Importantly, immune sera were found to be sufficient for conferring protection in naive mice, which was long-lived and cross-protective. Thus, molecular designing and presenting M2e immunogens on VLPs provide a promising platform for developing universal influenza vaccines without using adjuvants.

A Novel Subnucleocapsid Nanoplatform for Mucosal Vaccination against Influenza Virus That Targets the Ectodomain of Matrix Protein 2

“…Then, it would be interesting to investigate the potential of N SRS fused to these HA epitopes or to M2e to induce a cross-protective or heterosubtypic immunity against different strains of influenza virus A (including highly pathogenic influenza viruses such as H5N1). It is also conceivable to link to the N protein 3 different M2e sequences covering most of their diversity among avian and human influenza viruses, as it was previously done using replication-defective adenovirus vectors or VLPs (46,47). Fur- curves and each one of the other curves was evaluated according to the one-way ANOVA Tukey's multiple-comparison test (*, P Ͻ 0.05; **, P Ͻ 0.01; ***, P Ͻ 0.001) (statistical test was performed between day 2 and day 5 p.i.…”

Intranasal immunization with influenza antigens conjugated with cholera toxin subunit B stimulates broad spectrum immunity against influenza viruses

“…[11][12][13][14][15] Immunization with M2e confers cross-protection against various subtypes of influenza virus. 16 However, we speculate that a centralized HA2 conjugated with M2e could be the basis for an improved universal influenza vaccine to elicit a much potent immune response against a broad subtype of influenza viruses over using M2e or HA2 alone. Furthermore, it would also be advantageous to design a subunit universal vaccine to be delivered intranasally over intramuscular delivery, because (1) it would eliminate the discomfort and pain from injections and (2) the mucosal immune response is critical for clearance of respiratory tract pathogens.…”

Influenza M2 virus-like particles confer a broader range of cross protection to the strain-specific pre-existing immunity

“…A molecular construct with M2e tandem repeat (M2e5x) that contains M2e sequences derived from human, swine, and avian influenza viruses was developed in a membrane-anchored form and presented on enveloped VLPs (M2e5x VLP) as a potential universal influenza A vaccine [11–12]. Most pre-clinical studies have been carried out using naïve animals.…”