Fig. 6

Vaccinated chronic SCI mice are protected from a strain-matched influenza virus but not from a second challenge with a different strain. a Schematic of the experiment. Mice were divided into two groups (n = 15/group): one group received two doses of inactivated H3N2 vaccine and the other PBS 1 month prior to SCI. The two groups were further divided into two sub-groups, one receiving a spinal cord injury at thoracic level T9 (SCI, n = 10) and the other was not injured (CT, n = 5). Seven weeks post-injury, all mice were infected with H3N2 (HKx31) by intranasal route. Blood samples (open circles) were collected 4 days before SCI to confirm that all vaccinated mice had developed influenza-specific antibody titer and at day 0, 10, and 30 post-infection. The two groups of vaccinated mice (CT-vaccine, n = 5 and SCI-vaccine, n = 10) were challenged a second time with a different influenza strain, H1N1 (PR8). b Survival curve for the four groups of mice (n = 5/group for CT and 10/group for SCI) infected with H3N2 (HKx31). Only the chronic SCI mice that were not vaccinated (SCI-PBS) showed a dramatic decrease in survival. ****p < 0.0001, log-rank (Mantel-Cox) test. c The virus-specific antibody response in vaccinated SCI mice was similar to that of the vaccinated CT group (n = 5). **p < 0.01, ***p < 0.001. d Chronic SCI mice previously vaccinated produced neutralizing antibodies to the virus to the same extent as uninjured CT mice. *p < 0.05, **p < 0.01. e Vaccination of chronic SCI mice does not protect against a second challenge with a different influenza strain. Survival curves of H3N2-vaccinated uninjured CT (n = 5) and chronic SCI mice (n = 10) challenged with a dose of H1N1 virus. ****p < 0.0001, log-rank (Mantel-Cox)