Objective:To analyze the protective effect of a respiratory syncytial virus (RSV) vaccine based on bacterial outer membrane vesicle (OMV) in mice.Methods:The pre-fusion protein (preF) of RSV was linked to the surface of OMV through the transmembrane protein cytolysin A (ClyA) to form the nanovaccine OMV-preF. The morphological characteristics of OMV and OMV-preF were observed under a transmission electron microscope. OMV-preF was intramuscularly injected into BALB/c mice and the elicited humoral and cellular immune responses were evaluated. The protective effect of OMV-preF was assessed by challenging the immunized mice with RSV Long strain. One-way analysis of variance and Tukey test were used for statistical analysis.Results:The results showed that preF was stably expressed in OMV, and both OMV-preF and OMV exhibited a double-layer vesicle structures under the microscope. OMV-preF could significantly activate the cellular and humoral immune responses in mice, causing a significant increase in CD8 + T cells and CD19 + B cells as well as a significant increase in the serum level of specific IgG. The neutralizing antibodies produced in the immunized mice could significantly inhibit the replication of RSV Long strain in vivo. Conclusions:The nanovaccine OMV-preF can induce high-level humoral and cellular immune responses, and the antibodies produced following immunization can effectively inhibit viral replication. This study provides a new strategy for RSV subunit vaccines.

Objective:To analyze the protective effect of a respiratory syncytial virus (RSV) vaccine based on bacterial outer membrane vesicle (OMV) in mice.Methods:The pre-fusion protein (preF) of RSV was linked to the surface of OMV through the transmembrane protein cytolysin A (ClyA) to form the nanovaccine OMV-preF. The morphological characteristics of OMV and OMV-preF were observed under a transmission electron microscope. OMV-preF was intramuscularly injected into BALB/c mice and the elicited humoral and cellular immune responses were evaluated. The protective effect of OMV-preF was assessed by challenging the immunized mice with RSV Long strain. One-way analysis of variance and Tukey test were used for statistical analysis.Results:The results showed that preF was stably expressed in OMV, and both OMV-preF and OMV exhibited a double-layer vesicle structures under the microscope. OMV-preF could significantly activate the cellular and humoral immune responses in mice, causing a significant increase in CD8 + T cells and CD19 + B cells as well as a significant increase in the serum level of specific IgG. The neutralizing antibodies produced in the immunized mice could significantly inhibit the replication of RSV Long strain in vivo. Conclusions:The nanovaccine OMV-preF can induce high-level humoral and cellular immune responses, and the antibodies produced following immunization can effectively inhibit viral replication. This study provides a new strategy for RSV subunit vaccines.

Objective:To analyze antiviral activity against respiratory syncytial virus (RSV) of interferon (IFN)-α2b and IFN-λ1 on Hep2 cells and human airway epithelial (HAE) cells.Methods:IFN-α2b or IFN-λ1 was incubated with Hep2 cells after RSV infection, and 48 hours later, the cytopathic effect was observed, the viral load was determined using real time/reverse transcription quantitative polymerase chain reaction (RT qPCR), RSV F protein expression was detected using immunofluorescence, and cell survival rate was detected using crystal violet. HAE cells were incubated with IFN-α2b or IFN-λ1 for 24 hours, and then HAE were challenged with RSV. The viral load in the culture supernatant was determined on days 1-7 using RT qPCR, RSV F protein was determined with immunofluorescence and the viral titers in the culture supernatant was detected on day 7 by plaque assay.Results:In Hep2 cells, the CPE of the treatment groups (IFN-α2b and IFN-λ1) was alleviated compared to the virus control group, and the CPE of the high concentration group was lighter than that of the low concentration group. Different concentrations of IFN-α2b and IFN-λ1 could significantly reduce the viral load of RSV ( P<0.001), and the viral load of the high concentration group was significantly lower than that of the low concentration group ( P<0.001). In addition, IFN-α2b and IFN-λ1 could reduce the RSV F protein expression after RSV infection and improve cell survival rate. In HAE cells, IFN-α2b and IFN-λ1 could inhibit RSV virus replication, reduce virus titers ( P<0.001) and reduce RSV F protein expression. Conclusions:IFN-α2b and IFN-λ1 both showed great antiviral activity against RSV in Hep2 and HAE cells, providing data reference for the study of interferon against respiratory viruses.