TNF and infection: This work shows that FilF (i) is conserved among the strains of A. baumannii (ii) is a potential vaccine candidate predicted by in silico analysis (iii) raises high antibody titer in mouse (>64,000), (iv) reduces cytokine response [significant reduction in pro-inflammatory cytokines TNF-α, IL-33, IFN-γ, IL-6, and IL-1β (p < 0.001)], (v) protects mice from A. baumannii challenge (survival rate 50%) and (vi) reduces the severity of infection and bacterial burden in lungs of mice (4 log cycles reduction).