RBF protein with MA103 adjuvant elicited protective immunity against human respiratory syncytial virus in BALB/c mice.

The development of human respiratory syncytial virus (HRSV) vaccine was hampered by an enhanced respiratory disease due to Th2-biased immune response. In this study, adjuvants MA103 and aluminum phosphate (Adju-Phos) were used to verify the immunogenicity of RBF protein (F protein expressed by E. coli). Both adjuvants significantly increased the neutralizing antibody titer and the number of IFN-γ-secreting CD4+ T cells in mice. However, from the IgG1/IgG2a and IFN-γ/IL-4-secreting CD4+ T cells ratio, MA103 significantly enhanced Th1-biased immune response. The pathological damage of lung in group RBF/MA103 was slighter than that in group RBF/Adju-Phos. In addition, the HRSV copies in the lung of group RBF/MA103 decreased by approximately 3×log10. These results suggested that MA103 provided better protection in mice.