Chimeric virus-like particles containing a conserved region of the G protein in combination with a single peptide of the M2 protein confer protection against respiratory syncytial virus infection

To investigate the feasibility and efficacy of a virus-like particle (VLP) vaccine composed of the conserved antigenic epitopes of respiratory syncytial virus (RSV), the chimeric RSV VLPs HBcΔ-tG and HBcΔ-tG/M282-90 were generated based on the truncated hepatitis B virus core protein (HBcΔ). HBcΔ-tG consisted of HBcΔ, the conserved region (aa 144-204) of the RSV G protein. HBcΔ-tG was combined with a single peptide (aa 82-90) of the M2 protein to generate HBcΔ-tG/M282-90. Immunization of mice with the HBcΔ-tG or HBcΔ-tG/M282-90 VLPs elicited RSV-specific IgG and neutralizing antibody production and conferred protection against RSV infection. Compared with HBcΔ-tG, HBcΔ-tG/M282-90 induced decreased Th2 cytokine production (IL-4 and IL-5), increased Th1 cytokine response (IFN-γ, TNF-α, and IL-2), and increased ratios of IgG2a/IgG1 antibodies, thereby relieving pulmonary pathology upon subsequent RSV infection. Our results demonstrated that chimeric HBcΔ-tG/M282-90 VLPs represented an effective RSV subunit vaccine candidate.