Vlp Vaccine Based On A Murine Cytomegalovirus M84 Antigen Dominant Epitope

HCMV can cause severe CMV diseases in immunocompromised patients, especially in organ transplant recipients, AIDS patients and newborns with congenital CMV infection. Since HCMV becomes a great threat to public health, there is an urgent demand for an effective vaccine against HCMV. Virus-like particle(VLP) is a multi-protein construction lacking of viral genome and are therefore noninfectious and replication incompetent. Carrier proteins like HBc Ag have been shown to enhance immunogenicity of the fused antigen. In previous study, we found that M84 gene can induce cellular immune response in mice and protect mice from lethal dose challenge of MCMV. In this paper, we inserted an immunodominant epitope of M84 into HBc Ag and evaluate protective efficacy of this fusion protein in Balb/c mice.Two major parts of research have been included in this paper:1). Construction of HBc-M84 ep VLP vaccine : Gene sequence encoding51 amino acids including the M84 dominant epitope(297AYAGLFTPL305) was inserted into gene sequence encoding 1-149 amino acid of HBc Ag by replacing amino acids from position 75 to84,and was cloned and inserted into prokaryotic expression plasmid p ET28 a. The HBc-M84 ep recombinant protein was expressed in E.coli.After purification, the fusion protein was identified by western blotting.2). Protective efficacy evaluation of HBc-M84 ep subunit vaccine:Female Balb/c mice aged 6-8 weeks were immunized with 1μg, 6μg,30μg of HBc-M84 ep fusion protein given with or without MF59 twice at a 3-week interval. 3 weeks after secondary immunization, all the mice were challenged with a lethal dose of MCMV. Mice immunization with1μg HBc-M84 ep protein died within 7 days post challenge suggesting that this dosage can not protect mice from lethal MCMV infection. Even6μg, 30μg of HBc-M84 ep protein vaccine can only provide part protection with survival rate of 10%, 40% respectively. But, when adjuvanted with MF59, 1μg, 6μg, 30μg of HBc-M84 ep protein provide better or even complete protection against lethal MCMV with survival rate of 90%,100%,100% respectively. And this subunit vaccine can also reduce virus loads in mice salivary glands and spleens and induce specific antibody against MCMV.The results indicate that HBc-M84 ep fusion protein plus MF59 adjuvant can provide mice with effective protection against a lethal dose infection of MCMV. Along with the increase of antigen dose, protective efficacy against MCMV in Balb/c mice improved gradually. This research provides fundamental knowledge for new MCMV vaccine development and prevention against MCMV infection.