ABSTRACT
Respiratory syncytial virus (RSV) and influenza virus are the most significant pathogens causing respiratory tract diseases. Composite vaccines are useful in reducing the number of vaccination and confer protection against multiple infectious agents. In this study, we generated fusion of RSV G protein core fragment (amino acid residues 131 to 230) and influenza HA1 globular head domain (amino acid residues 62 to 284) as a dual vaccine candidate. This fusion protein, Gcf-HA1, was bacterially expressed, purified by metal resin affinity chromatography, and refolded in PBS. BALB/c mice were intranasally immunized with Gcf-HA1 in combination with a mucosal adjuvant, cholera toxin (CT). Both serum IgG and mucosal IgA responses specific to Gcf and HA1 were significantly increased in Gcf-HA1/CT-vaccinated mice. To determine the protective efficacy of Gcf-HA1/CT vaccine, immunized mice were challenged with RSV (A2 strain) or influenza virus (A/PR/8/34). Neither detectable viral replication nor pathology was observed in the lungs of the immune mice. These results demonstrate that immunity induced by intranasal Gcf-HA1/CT immunization confers complete protection against both RSV and homologous influenza virus infection, suggesting our Gcf-HA1 vaccine candidate could be further developed as a dual subunit vaccine against RSV and influenza virus.
Subject(s)
Animals , Mice , Cholera Toxin , Chorionic Gonadotropin, beta Subunit, Human , Chromatography, Affinity , GTP-Binding Proteins , Head , Hemagglutinins , Immunization , Immunoglobulin A , Immunoglobulin G , Influenza, Human , Lung , Orthomyxoviridae , Peptide Fragments , Respiratory Syncytial Viruses , Respiratory Tract Diseases , Vaccination , VaccinesABSTRACT
Objective To construct a plasmid DNA encoding G glycoprotein of respiratory syncytial virus(RSV) and investigate the protective immune response against RSV infection. Methods Recombinant plasmid DNA of pcDNA3.1~G was constructed by standard RT-PCR based cloning procedure. The immunogenicity of recombinant G protein transiently expressed in HEK293 cells was detected by Western blot. BABL/c mice were intramuscularly immunized with pcDNA3.1~G. Samples of lung, sera, bronchoalveolar lavage fluid(BALF) were collected before and after RSV challenge; virus titer in lung was detected by viral titration; sections of paraffin embedding lung tissues were stained by haematoxylin and eosin(HE) for histological analyses; sera anti-RSV IgG levels were examined by ELISA; Th1/Th2 cytokine were detected by ELISA kit, the T lymphocyte subsets of BALF was determined by immunefluorescence staining followed by flow cytometry. Results Plasmid DNA of pcDNA3.1~G was successfully constructed. The expressed target protein possesses immunogenicity. After challenge, pcDNA3.1~G immunized mice presented relieved pathological changes in lung as well as reduced lung viral titers. The RSV specific IgG was detected in sera of immunized mice. There was significantly increased number of CD25~+CD4~+ T cells in mice BALF. Conclusion We constructed a pcDNA3.1~G plasmid DNA vaccination which can induce evident protective cellular immunity against RSV infection in mice with the increased number of CD25~+CD4~+ T cell subpopulation.