Fig 4. Neutralization and protection following vaccination with UV-inactivated viruses.
Six-week old C57bl/6 mice were vaccinated with 5μg of each parental (CHIK or SFV) or chimeric viruses (ΔDomA, ΔDomB, ΔDomC, ΔDomA+B) inactivated with ultraviolet (UV) radiation. Mice received a second injection 28 days later. Groups of mice were then challenged with 105 PFU of either CHIKV or SFV. A) Neutralizing antibody responses against both CHIK and SFV were assessed prior to challenge using a luciferase based assay. Infectious virus was mixed with a 1:20 dilution of serum and used to infect cells following incubation overnight at 4°C. Luciferase activity was measured in cell lysates after five hours of infection. Data are expressed as fold neutralization, normalized to mock serum. Mice challenged with SFV were monitored for B) weight loss and C) survival. Weight loss is expressed as the mean percentage of starting weight of the group. D) Change in footpad width was used as a marker of CHIKV disease. Data are presented as percent change as compared to pre-challenge levels.