ABSTRACT
Objective:To construct a novel respiratory syncytial virus (RSV) vaccine based on a recombinant influenza virus vector and evaluate its immune protective effects in mice.Methods:A recombinant H1N1 influenza A virus (IAV) expressing the extracellular domain (Gecto) of RSV A2 G protein was constructed and rescued, named as PR8NAGecto/WSN. After in vitro verification of the Gecto expression and PR8NAGecto/WSN growth kinetics, a single dose of PR8NAGecto/WSN was used to immunize BALB/c mice through intranasal administration to evaluate the efficacy of PR8NAGecto/WSN by assessing humoral (IgG, neutralizing antibody), mucosal (IgA) and cellular immunity (IFN-γ ELISPOT). Four weeks after immunization, the mice were challenged with RSV A2 or RSV B9320 to evaluate the protective effects of PR8NAGecto/WSN by analyzing mouse body weight changes, lung tissue virus titers and pathological changes. Results:A single-dose intranasal immunization with PR8NAGecto/WSN induced robust humoral, mucosal and cellular immunity in mice. Moreover, the mice in the immunized group had lower lung virus loads and mild lung pathological damages following the challenge with RSV A or RSV B subtype as compared with the control group.Conclusions:A single-dose intranasal immunization with PR8NAGecto/WSN induces robust immunity and provide protection against RSV A and B challenges in mice. This study provides new ideas and reference for the development of novel mucosal vaccines against RSV.
ABSTRACT
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its variants continue to spread around the world, posing a great threat to global economic and public health. Influenza A virus, a major cause of influenza, has a wide host range and evolves rapidly. Influenza pandemics, which occur every 20 to 40 years, annual seasonal influenza epidemics, severe influenza and animal influenza viruses are all serious threats to public health. Clinical manifestations of infections caused by the two pathogens are very similar. It is of great significance to develop an effective bivalent vaccine for controlling alternating epidemics or co-infection of the two pathogens. This article reviewed the progress in the development of bivalent vaccines against SARS-CoV-2 and influenza A virus based on different platforms.
ABSTRACT
Objective:To construct a bivalent DNA vaccine against SARS-CoV-2 and influenza A virus H3N2 and to evaluate its immunogenicity in mice.Methods:The coding sequences for spike 1 (S1) protein of SARS-CoV-2 Beta variant and hemagglutinin (HA) of influenza A virus Cambodia (H3N2) strain were codon-optimized and synthesized. The two coding genes were ligated by the self-cleaving 2A peptide using over-lapping PCR to construct S1-2A-HA fragment, which was inserted into pVRC vector to construct the bivalent DNA vaccine, named as pVRC-S1-2A-HA. Indirect immunofluorescence assay (IFA) and Western blot were performed to detect the expression of S1 and HA proteins. BALB/c mice were immunized with pVRC-S1-2A-HA by intramuscular injection and electroporation. The humoral immune responses induced in mice were detected by indirect ELISA, pseudovirus neutralization assay and hemagglutination inhibition assay. Cellular immune responses were detected by IFN-γ ELISPOT, intracellular cytokine staining (ICS) and cytometric bead array (CBA).Results:The bivalent DNA vaccine pVRC-S1-2A-HA could express S1 and HA proteins in vitro. Specific cellular immune responses against S1 protein and specific IgG antibody against HA protein were significantly induced in mice with single-dose immunization. The antigen-specific immunity was significantly enhanced after booster immunization. The geometric mean titer (GMT) of specific IgG antibody increased to 3 251 for S1 protein and 45 407 for HA protein after two-dose immunization. Moreover, the S1-specific T cells increased to 1 238 SFC/10 6 cells. ICS results indicated that the booster vaccination induced CD4 + T and CD8 + T cells to produce IL-2, IFN-γ and TNF-α in mice. The secretion of various cytokines including IL-2, IL- 4, IL-6, IL-10 and IFN-γ in mouse splenocytes was induced after single-dose immunization. Conclusions:A bivalent DNA vaccine against SARS-CoV-2 and influenza A virus H3N2 was constructed and could induce S1- and HA-specific humoral and cellular immune responses in mice, suggesting the great potential of it for further development and application.