Zishu Pan, Lei Qiao, Yuan Zhang and Xiufen Zou
State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, China
Respiratory syncytial virus (RSV), a major respiratory pathogen, is the leading cause of severe bronchiolitis or even death in infants. To date, no RSV vaccines are available partially due to vaccine enhanced disease (VED) with conventional formalin inactivated RSV vaccines. To investigate the feasibility and efficacy of the virus-like particles (VLPs) vaccine comprising the conserved antigen epitopes of RSV, we constructed the two RSV VLPs based on the hepatitis B virus core protein (HBc). The HBc-tG consisted of the HBc and conserved region of RSV G protein and the HBc-tG/M2 was generated from HBc-tG fused with the CTL epitope of the M2 protein. The potential of the HBc-tG and HBc-tG/M2 VLPs were evaluated in a mouse model. The results suggested that both VLPs elicited high levels of RSV-specific antibodies and cellular immune responses. Sera antibody isotype (IgG2a/IgG1) and cytokines profile of immunized mice revealed that HBc-tG VLPs stimulated a Th1/Th2 mixed but Th2-biased immune response and led to lung tissue pathology damage after RSV challenge infection. HBc-tG/M2 VLPs induced a Th1-like predominated response and protected mice from RSV challenge infection without enhanced lung pathology. Our results demonstrated that the novel VLPs may provide an effective RSV subunit vaccine candidate.